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Friction and Wear of Materials Surfaces

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Mechanics of Materials".

Deadline for manuscript submissions: closed (10 April 2023) | Viewed by 72298

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Special Issue Editor

Dr. Andrzej Dzierwa

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Guest Editor

Department of Manufacturing Processes and Production Engineering, Faculty of Mechanical Engineering, Rzeszow University of Technology, Powstancow Warszawy 8, 35-959 Rzeszow, Poland
Interests: tribology; friction; wear; surface engineering; surface metrology; manufacturing processes
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The surface topography is one of the most important factors determining the quality of a surface layer. It defines a set of all overlapping irregularities of surface resulting from the machining processes and wear of materials. Irregularities of surface have varied dimensions, shapes and location. The quality of the surface has a significant impact on the operational properties of machine elements, which are expressed, among others, through: frictional conditions on contact surfaces, corrosion resistance, fatigue strength, contact stresses or tightness of joints. All mechanical, physical, chemical, and geometrical aspects of the surface contact affect the surface interactions and thereby also the tribological characteristics of the system.

A number of scientists studied the effect of surface topography and materials properties on the tribological performance of sliding elements. However accessible papers contain ambiguous and sometimes contradictory opinions about connections between values of surface topography parameters, materials properties and various tribological properties of sliding pairs. In addition a continuous development of measuring equipment makes possible more precision measurement and as a consequence makes possible extended analysis of phenomena taking part on surfaces in frictional contact.

Therefore the aim of this special issue is to collect high-quality research papers that focus on friction and wear of materials surfaces. We are looking forward to receiving your submissions.

Dr. Andrzej Dzierwa
Guest Editor

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Keywords

Friction
Wear
Tribology
Surface topography
Surface engineering
Materials
Surface metrology

Published Papers (35 papers)

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20 pages, 6694 KiB

Open AccessArticle

Experimental Investigation of Engine Valve Train Friction Considering Effects of Operating Conditions and WPC Surface Treatment

by Muhammad Usman Bhutta, Muhammad Huzaifa Najeeb, Muhammad Usman Abdullah, Samiur Rahman Shah, Muhammad Khurram, Riaz Ahmad Mufti, Kiyotaka Ogawa, Jawad Aslam, Rehan Zahid, Mian Ashfaq Ali and Muazzam Arshad

Materials 2023, 16(9), 3431; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16093431 - 28 Apr 2023

Viewed by 1668

Reduction in friction ensures fuel economy, control on emissions and durability of components in internal combustion engines. A modern gasoline internal combustion engine was instrumented to determine the friction values at the cam–roller interface considering the effects of surface treatment and engine operating [...] Read more.

Reduction in friction ensures fuel economy, control on emissions and durability of components in internal combustion engines. A modern gasoline internal combustion engine was instrumented to determine the friction values at the cam–roller interface considering the effects of surface treatment and engine operating state. A series of tests under different operating speeds and lubricant inlet temperatures were undertaken using both an original surface roller and a Wonder Process Craft (WPC) surface-treated engine roller. The results clearly revealed a substantial reduction in friction magnitude for the WPC surface-treated engine roller in comparison to the original roller while operating under similar conditions, indicating their strong potential for employment in engines. An increase in friction with the rise in temperature was also observed for both types of rollers, whereas increased lubricant entraining velocity due to higher operating speed had the opposite impact. A considerable reduction in frictional drive torque ranging from 8% to 28% was observed by employing the WPC-treated roller in comparison to original/untreated roller at various operating conditions, which signifies the strong potential for employment of WPC surface treatment in the roller/follower valve train engines. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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17 pages, 2408 KiB

Open AccessArticle

Damage Caused by Material Defects of Carbon Composites Used on Various Types of Railway Pantographs

by Małgorzata Kuźnar

Materials 2023, 16(5), 1839; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16051839 - 23 Feb 2023

Cited by 1 | Viewed by 1193

Mainstream materials of the railway pantograph strips are carbon composites. They are subject to wear during use, as well as various types of damage. It is important that their operation time is as long as possible and that they are not damaged, as [...] Read more.

Mainstream materials of the railway pantograph strips are carbon composites. They are subject to wear during use, as well as various types of damage. It is important that their operation time is as long as possible and that they are not damaged, as it may damage the remaining elements of the pantograph and the overhead contact line. As part of the article, three types of pantographs were tested: AKP−4E, 5ZL, and 150 DSA. They had carbon sliding strips made of MY7A2 material. By testing the same material on different types of current collectors, it was possible to check what impact the wear and damage of the sliding strips has on (among others) the method of their installation, i.e., whether the damage to the strips depends on the type of current collector and what is the participation of damage caused by material defects. As a result of the research, it was found that the type of pantograph on which it is used has an undoubted influence on the damage characteristics of the carbon sliding strips, whereas the damage caused by material defects can be classified as a more general group—the group of damage of a sliding strip, which also includes overburning of a carbon sliding strip. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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14 pages, 3699 KiB

Open AccessArticle

A Novel Catalytic Ceramic Conversion Treatment of Zr702 to Combat Wear

by Xinhe Xiong, Xiaoying Li, James Alexander, Zhenxue Zhang and Hanshan Dong

Materials 2023, 16(5), 1763; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16051763 - 21 Feb 2023

Viewed by 950

Zr and its alloys are widely used in multiple areas, including the nuclear and medical fields. Previous studies indicate that a ceramic conversion treatment (C2T) of Zr-based alloys can address the issues of low hardness, high friction, and poor wear resistance of Zr [...] Read more.

Zr and its alloys are widely used in multiple areas, including the nuclear and medical fields. Previous studies indicate that a ceramic conversion treatment (C2T) of Zr-based alloys can address the issues of low hardness, high friction, and poor wear resistance of Zr based alloys. This paper introduced a novel catalytic ceramic conversion treatment (C3T) to Zr702 by pre-depositing a catalytic film (such as silver, gold, platinum, etc.) before the ceramic conversion treatment, which efficiently promoted the C2T process, in terms of reduced treatment times, with a thick, good quality, surface ceramic layer. The formed ceramic layer significantly improved the surface hardness and tribological properties of Zr702 alloy. Compared with conventional C2T, the C3T technique provided two orders of magnitude reduction of wear factor and reduced the coefficient of friction from 0.65 to <0.25. Among the C3T samples, the C3TAg and the C3TAu samples have the highest wear resistance and lowest CoF, mainly due to the self-lubricant formation during the wear processes. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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23 pages, 9137 KiB

Open AccessArticle

Dry Sliding Wear Studies on Sillimanite and B₄C Reinforced Aluminium Hybrid Composites Fabricated by Vacuum Assisted Stir Casting Process

by Manickaraj Pethuraj, Marimuthu Uthayakumar, Shanmugavel Rajesh, Mohd Shukry Abdul Majid, Sivaprakasam Rajakarunakaran and Magdalena Niemczewska-Wójcik

Materials 2023, 16(1), 259; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16010259 - 27 Dec 2022

Cited by 4 | Viewed by 1202

This paper presents the results of studies to understand the influence of hybridisation on mechanical and tribological behaviour as well as dry sliding wear of aluminium metal matrix composites. Sillimanite and boron carbide (B₄C) were used as primary and secondary reinforcements [...] Read more.

This paper presents the results of studies to understand the influence of hybridisation on mechanical and tribological behaviour as well as dry sliding wear of aluminium metal matrix composites. Sillimanite and boron carbide (B₄C) were used as primary and secondary reinforcements and pure aluminium was used as the matrix material. The composite was fabricated by using a vacuum assisted stir casting process. Different research instruments were used, including a scanning electron microscope with EDX spectrometer, a surface measurement device, a thermal image analyser, as well as a tribotester. The results show that tensile, impact strength and hardness of the hybridised composites are superior (a step ahead) than unreinforced and primary composites. The wear behaviour of the fabricated specimens was tested for the dry sliding wear behaviour under the load range of 10–50 N with the steps of 20 N for the sliding velocities 0.75, 1.5 and 2.25 m/s over a distance of 1000 m. The wear rate increased with load and decreased as the wt.% of reinforcement increased. The wear rate of the composite with 10 wt.% Al₂SiO₅ was approximately 44% lower than that of the composite with 5 wt.% Al₂SiO₅. The same dependence was noted for hybrid composite (5 wt.% Al₂SiO₅ + 5 wt.% B₄C)—the wear rate was approximately 50.8% lower than that of the composite with 5 wt.% Al₂SiO₅ under the same test condition. The friction coefficient decreased as the weight percentage of the reinforcement (Al₂SiO₅ and B₄C) increased due to the uniform distribution of the reinforcement on the surface of the composites. The main wear mechanism of the studied materials was abrasion wear. The wear mechanism of the composite had tribochemical type. It involved the oxidation and transfer of the material, which formed protective tribolayers ensuring an additional sliding process. The mechanism that played the main role in the wear process of the composites was a combination of abrasive, adhesive and oxidative wear. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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16 pages, 11175 KiB

Open AccessArticle

Experimental Study on the Effect of Micro-Texture on EHL Point-Contact Film Thickness Subject to Sliding Conditions

by Jianxin Sun, Linqing Bai, Feng Guo and Zulfiqar Ahmad Khan

Materials 2022, 15(22), 7926; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15227926 - 09 Nov 2022

Cited by 1 | Viewed by 1210

Processing texture on contact surfaces can improve the friction performance of mechanical comments. In this research, micro-dimple textures with various parameter were processed on a steel ball’s surface with a picosecond laser. Then, the EHL (elastohydrodynamic lubrication) oil film thickness was measured on [...] Read more.

Processing texture on contact surfaces can improve the friction performance of mechanical comments. In this research, micro-dimple textures with various parameter were processed on a steel ball’s surface with a picosecond laser. Then, the EHL (elastohydrodynamic lubrication) oil film thickness was measured on an optical ball-on-disc tribometer subjected to pure sliding conditions. The effects of sliding velocity, load, dimple location and dimple depth on the film thickness were analyzed. The results showed that the dimple affected the pressure distribution in the contact area, which in turn changed the distribution of the local film thickness. An increase in the local film thickness occurred between the dimple and outlet of the contact region, while a decrease in the film thickness formed from the dimple to the entrance of the contact area and both sides of the dimple’s edge. Velocity and applied loads affected the film thickness distribution as well. As the sliding velocity increased, the film thickness increasing region enlarged, while the film thickness-decreasing area shrank. The increase in load resulted in a negative effect on the increase in film thickness. This study will provide a reference for point-contact designs with low friction conditions. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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21 pages, 7865 KiB

Open AccessArticle

Influence of Anodizing Parameters on Tribological Properties and Wettability of Al₂O₃ Layers Produced on the EN AW-5251 Aluminum Alloy

by Mateusz Niedźwiedź, Marek Bara, Władysław Skoneczny, Sławomir Kaptacz and Grzegorz Dercz

Materials 2022, 15(21), 7732; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15217732 - 03 Nov 2022

Cited by 2 | Viewed by 1165

The article presents the effect of anodizing parameters of the EN AW-5251 aluminum alloy on the thickness and roughness of Al₂O₃ layers as well as their wettability and tribological properties in a sliding combination with the T7W material. The input [...] Read more.

The article presents the effect of anodizing parameters of the EN AW-5251 aluminum alloy on the thickness and roughness of Al₂O₃ layers as well as their wettability and tribological properties in a sliding combination with the T7W material. The input variables were the current density of 1, 2, 3 A/dm² and the electrolyte temperature of 283, 293, 303 K. The tribological tests were performed on the T-17 tester in reciprocating motion, in conditions of technically dry friction. The tests were carried out on a 15 km road with a constant average slip speed of 0.2 m/s and a constant unit pressure of 1 MPa. The measurement of the wettability of the layers was performed using the sitting drop method, determining the contact angles on the basis of which the surface free energy was calculated. The profilographometric measurements were made. The analysis of the test results showed that the anodizing parameters significantly affect the thickness of the Al₂O₃ layers. The performed correlation analysis also showed a significant relationship between the roughness parameters and the wettability of the surface of the layers, which affects the ability to create and maintain a sliding film, which in turn translates into sliding resistance and wear of the T7W material. The analysis of friction and wear tests showed that the layer with hydrophobic properties produced at a current density of 1 A/dm² in an electrolyte at a temperature of 283 K is the most favorable for sliding associations with T7W material. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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14 pages, 6705 KiB

Open AccessArticle

Casing Wear and Wear Factors: New Experimental Study and Analysis

by Omer Alnoor Osman, Necar Merah, Mohammed Abdul Samad, Mirza Murtuza Ali Baig, Robello Samuel, Meshari Alshalan and Amjad Alshaarawi

Materials 2022, 15(19), 6544; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15196544 - 21 Sep 2022

Cited by 6 | Viewed by 2001

To understand and quantify casing wear during drilling operations, an experimental setup with real drill pipe joints (DPJ) and casings was designed and used to carry out wear tests, simulating various operating conditions and environments. P110 steel casing samples were tested under dry [...] Read more.

To understand and quantify casing wear during drilling operations, an experimental setup with real drill pipe joints (DPJ) and casings was designed and used to carry out wear tests, simulating various operating conditions and environments. P110 steel casing samples were tested under dry and wet conditions. Actual field oil- and water-based fluids were utilized to lubricate the contact area at two different side loads (1000 N and 1400 N) and DPJ speeds (115 and 207 rpm). The results show that for the same testing conditions, the casing wear volume and wear factor under water-based lubrication were more than twice those obtained under oil-based fluid testing. As expected, the wear volume and wear factor were highest under dry conditions. Moreover, it was noticed that, as the normal load was increased at a constant rotational speed (rpm), the wear factor increased. On the other hand, raising the rotational speed at the same applied load reduced the casing wear factor, due to the observed absence of adhesive wear and possible localized softening effects at higher speeds. SEM analyses of the worn areas showed that under dry conditions, the main wear mechanisms were abrasion and delamination. However, both adhesive wear and abrasive wear mechanisms were observed under oil-based lubrication. The energy dispersive spectroscopy (EDS) analysis of the worn surface revealed that at higher loads and speeds, a heavy transfer of particles from the oil-based lubricant took place. On the other hand, some contaminants of the water-based lubricant were observed on the worn surfaces. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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9 pages, 4841 KiB

Open AccessArticle

Wear Performance of Circular Shim against Cam in Engine Bench Test

by Cheng-Di Li, Jing-Si Wang, Xu Han, Feng-Ming Du, Geng-Shuo Liu and Ren-Jin Lin

Materials 2022, 15(18), 6293; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15186293 - 10 Sep 2022

Viewed by 1446

Unlike the conventional engine, the valve train of a certain type of engine uses a circular shim instead of a tappet to wear against the cam. To verify the reliability of the shim, an engine bench test was used to test its wear [...] Read more.

Unlike the conventional engine, the valve train of a certain type of engine uses a circular shim instead of a tappet to wear against the cam. To verify the reliability of the shim, an engine bench test was used to test its wear performance. The total duration of the bench test was 1000 h, which was divided into three stages. In each stage, the test equipment was stopped, and the shims were disassembled to observe the surface morphology during the worn process. Precious long-term data were obtained. With the extension of the bench test time, weight loss increased. The maximum weight loss occurs 1000 h after worn, which is about twice that of 350 h. During the wear process, a plastic flow of material was found on the subsurface, and fatigue wear marks occurred on the surface. With an increase in test time, the wear marks increased, leading to material spalling and the formation of pits. The wear mechanism was the mixed wear of fatigue wear and adhesive wear. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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19 pages, 11274 KiB

Open AccessArticle

Effect of Different Laser Groove Texture Collation Frequency on Tribological Properties of 0Cr17Ni7Al Stainless Steel

by Liguang Yang, Wensuo Ma, Fei Gao and Shiping Xi

Materials 2022, 15(13), 4419; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15134419 - 22 Jun 2022

Cited by 3 | Viewed by 1314

Laser surface texture is very effective in antifriction systems, but its applications and research in dry friction are not enough. In this study, the groove texture was prepared on the surface of 0Cr17Ni7Al stainless steel, a common material of sliding bearing, by nanosecond [...] Read more.

Laser surface texture is very effective in antifriction systems, but its applications and research in dry friction are not enough. In this study, the groove texture was prepared on the surface of 0Cr17Ni7Al stainless steel, a common material of sliding bearing, by nanosecond and femtosecond laser, respectively. The tribological properties of the two kinds of laser groove textures with different collision frequencies were studied in depth. The results show that the friction coefficients of groove texture prepared by nanosecond and picosecond lasers are lower than that of the untextured surface. The antifriction characteristics of the laser texture are very good. The average friction coefficient of nanosecond texture at the rotation radius of 15 mm is Z = 0.7318. The best friction-reducing effect is achieved. In general, the friction coefficient of nanosecond texture is lower than that of picosecond texture. When the friction radius is 22.5 mm and the number of collisions is 24,000, the lowest picosecond texture wear rate is H = 3.342 × 10⁻⁴ mm³/N·mm. However, when the radius is 15 mm and the collision frequency is 36,000 times, the wear rate of nanosecond texture reaches the highest H = 13.680 × 10⁻⁴ mm³/N·mm. The wear rate of the untextured surface has been exceeded. It can be seen that not all rotation radius textures are more wear-resistant than untextured surfaces. In addition, nanosecond groove texture and picosecond groove texture seem to produce different tribological properties. It is found that, under the same friction experimental conditions, different collision frequencies will affect the friction and wear properties of nanosecond and picosecond groove-textured surfaces. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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14 pages, 3810 KiB

Open AccessFeature PaperArticle

Optimization of Alumina Ceramics Corrosion Resistance in Nitric Acid

by Ivana Ropuš, Lidija Ćurković, Hrvoje Cajner and Sanda Rončević

Materials 2022, 15(7), 2579; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15072579 - 31 Mar 2022

Cited by 5 | Viewed by 2083

The development of ceramic materials resistance in various aggressive media combined with required mechanical properties is of considerable importance for enabling the wider application of ceramics. The corrosion resistance of ceramic materials depends on their purity and microstructure, the kind of aggressive media [...] Read more.

The development of ceramic materials resistance in various aggressive media combined with required mechanical properties is of considerable importance for enabling the wider application of ceramics. The corrosion resistance of ceramic materials depends on their purity and microstructure, the kind of aggressive media used and the ambient temperature. Therefore, the corrosion resistance of alumina ceramics in aqueous HNO₃ solutions of concentrations of 0.50 mol dm⁻³, 1.25 mol dm⁻³ and 2.00 mol dm⁻³ and different exposure times—up to 10 days—have been studied. The influence of temperature (25, 40 and 55 °C) was also monitored. The evaluation of Al₂O₃ ceramics corrosion resistance was based on the concentration measurements of eluted Al³⁺, Ca²⁺, Fe³⁺, Mg²⁺, Na⁺ and Si⁴⁺ ions obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES), as well as density measurements of the investigated alumina ceramics. The response surface methodology (RSM) was used for the optimization of parameters within the experimental “sample-corrosive media” area. The exposure of alumina ceramics to aqueous HNO₃ solutions was conducted according to the Box–Behnken design. After the regression functions were defined, conditions to achieve the maximum corrosion resistance of the sintered ceramics were determined by optimization within the experimental area. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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17 pages, 17839 KiB

Open AccessArticle

Effects of Microstructure Modification by Friction Surfacing on Wear Behavior of Al Alloys with Different Si Contents

by Malte R. Schütte, Jonas Ehrich, Dominic Linsler and Stefanie Hanke

Materials 2022, 15(5), 1641; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15051641 - 22 Feb 2022

Cited by 8 | Viewed by 1740

In this work, Al alloys with 6.6%, 10.4%, and 14.6% Si were deposited as thick coatings by Friction Surfacing (FS), resulting in grain refinement and spheroidization of needle-shaped eutectic Si phase. Lubricated sliding wear tests were performed on a pin-on-disc tribometer using Al-Si [...] Read more.

In this work, Al alloys with 6.6%, 10.4%, and 14.6% Si were deposited as thick coatings by Friction Surfacing (FS), resulting in grain refinement and spheroidization of needle-shaped eutectic Si phase. Lubricated sliding wear tests were performed on a pin-on-disc tribometer using Al-Si alloys in as-cast and FS processed states as pins and 42CrMo4 steel discs. The chemical composition of the worn surfaces was analyzed by X-ray photoelectron spectroscopy (XPS). The wear mechanisms were studied by scanning electron microscopy (SEM) and focused ion beam (FIB), and the wear was evaluated by measuring the weight loss of the samples. For the hypoeutectic alloys, spheroidization of the Si phase particles in particular leads to a significant improvement in wear resistance. The needle-shaped Si phase in as-cast state fractures during the wear test and small fragments easily detach from the surface. The spherical Si phase particles in the FS state also break away from the surface, but to a smaller extent. No reduction in wear due to FS was observed for the hypereutectic alloy. Here, large bulky primary Si phase particles are already present in the as-cast state and do not change significantly during FS, providing high wear resistance in both material states. This study highlights the mechanisms and limitations of improved wear resistance of Si-rich Al alloys deposited as thick coatings by Friction Surfacing. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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18 pages, 19706 KiB

Open AccessArticle

Modeling of Surface Topography after Milling with a Lens-Shaped End-Mill, Considering Runout

by Karol Żurawski, Piotr Żurek, Andrzej Kawalec, Anna Bazan and Adam Olko

Materials 2022, 15(3), 1188; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15031188 - 04 Feb 2022

Cited by 4 | Viewed by 1617

The paper presents a method of forecasting the product surface topography after five-axis machining with a lens-shaped end-mill. Surface roughness is one of the key parameters considered when assessing the effectiveness of the machining process, especially in the aviation, automotive, tooling and medical [...] Read more.

The paper presents a method of forecasting the product surface topography after five-axis machining with a lens-shaped end-mill. Surface roughness is one of the key parameters considered when assessing the effectiveness of the machining process, especially in the aviation, automotive, tooling and medical equipment industries. The developed method, the first published, presented in the paper is based on the analytical equations of the trajectory of the cutting edge motion, on the basis of which the cutter action surface is generated. The developed model takes into account: cutting depth, cutting width, feed, lead angle and radial runout. Experimental studies were conducted using three different materials: 40HM steel, Al7035 aluminum alloy and Ti Grade 5 titanium alloy. Various values of the cutting width parameters and different feeds were used in the tests. Based on the results of the experimental tests, an empirical model (response surface model) was determined and was then used to verify the simulation model. The simulation results and the results of experimental tests were compared and conclusions were drawn regarding the developed models. The developed models supported by numerical simulation can be used to approximately estimate the influence of the width of cut

b_{r}

and feed

f_{t}

on selected height characteristics

S_{a}

and

\hat{S z}

of the geometric structure of the surface (GSS) after machining with a lens-shaped end-mill in terms of the process parameters adopted in the tests. It was found that the influence of the

f_{t}

on the

S_{a}

and

\hat{S z}

is greater for small values of

b_{r}

. The effect of

b_{r}

is greater with lower

f_{t}

values. The cutting width

b_{r}

has the greatest influence on

S_{a}

and

\hat{S z}

, and

f_{t}

and the interaction of these parameters has the least influence. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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13 pages, 3412 KiB

Open AccessArticle

The Object Segmentation from the Microstructure of a FSW Dissimilar Weld

by Anna Wójcicka, Łukasz Walusiak, Krzysztof Mroczka, Joanna Krystyna Jaworek-Korjakowska, Krzysztof Oprzędkiewicz and Zygmunt Wrobel

Materials 2022, 15(3), 1129; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15031129 - 31 Jan 2022

Viewed by 1876

Friction stir welding (FSW) is an environmentally friendly, solid-state welding technique. In this research work, we analyze the microstructure of a new type of FSW weld applying a two- stage framework based on image processing algorithms containing a segmentation step and microstructure analysis [...] Read more.

Friction stir welding (FSW) is an environmentally friendly, solid-state welding technique. In this research work, we analyze the microstructure of a new type of FSW weld applying a two- stage framework based on image processing algorithms containing a segmentation step and microstructure analysis of objects occurring in different layers. A dual-speed tool as used to prepare the tested weld. In this paper, we present the segmentation method for recognizing areas containing particles forming bands in the microstructure of a dissimilar weld of aluminum alloys made by FSW technology. A digital analysis was performed on the images obtained using an Olympus GX51 light microscope. The image analysis process consisted of basic segmentation methods in conjunction with domain knowledge and object detection located in different layers of a weld using morphological operations and point transformations. These methods proved to be effective in the analysis of the microstructure images corrupted by noise. The segmentation parts as well as single objects were separated enough to analyze the distribution on different layers of the specimen and the variability of shape and size of the underlying microstructures, which was not possible without computer vision support. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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10 pages, 268 KiB

Open AccessArticle

Influence of pH Cycling on Erosive Wear and Color Stability of High-Viscosity Glass Ionomer Cements

by Maja Zečević Čulina, Valentina Brzović Rajić, Ivan Šalinović, Eva Klarić, Luka Marković and Ana Ivanišević

Materials 2022, 15(3), 923; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15030923 - 25 Jan 2022

Cited by 8 | Viewed by 2544

The purpose of this in vitro study was to evaluate erosive wear and change in color of high-viscosity glass ionomer cements after pH cycling in two erosive media. There were 3 experimental groups with 22 samples each, (I) EQUIA Forte HT without coat, [...] Read more.

The purpose of this in vitro study was to evaluate erosive wear and change in color of high-viscosity glass ionomer cements after pH cycling in two erosive media. There were 3 experimental groups with 22 samples each, (I) EQUIA Forte HT without coat, (II) Fuji IX and (III) Ketac Universal Aplicap. Each group was randomly divided into three subgroups (n = 6–8) further exposed to different environments, (1) distilled water, (2) green tea (pH 3.78) and (3) Aceto balsamico vinegar (pH 3.0). Mass and L* a* b* values were recorded before and after pH cycling. The samples in subgroups 2 and 3 were exposed to the acidic media two times a day for 10 min, over a period of 14 days. The differences among materials and erosive effects of the three media were tested using three-way analyses of variance with post hoc LSD test at the significance level p < 0.05. The effect of pH cycling in Aceto balsamico and green tea was degrading for all three materials. pH cycling in Aceto balsamico caused significantly higher erosive wear than pH cycling in Fuzetea and storage in distilled water, in all materials (p < 0.05). pH cycling in both acidic media and in the control group resulted in a significant change in L* a* and b* (p < 0.05). The L* value decreased significantly and the a* and b* values increased significantly (p < 0.05). Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

16 pages, 8253 KiB

Open AccessArticle

The Role of Chemical Composition of High-Manganese Cast Steels on Wear of Excavating Chain in Railway Shoulder Bed Ballast Cleaning Machine

by Janusz Krawczyk, Michał Bembenek and Jan Pawlik

Materials 2021, 14(24), 7794; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14247794 - 16 Dec 2021

Cited by 11 | Viewed by 2096

The main task for a ballast bed is to transmit the sleeper pressure in a form of stress cone to the subsoil, provide proper drainage and resist the sleeper displacement. Poorly maintained ballast could severely limit the maximum speed capacity and create further [...] Read more.

The main task for a ballast bed is to transmit the sleeper pressure in a form of stress cone to the subsoil, provide proper drainage and resist the sleeper displacement. Poorly maintained ballast could severely limit the maximum speed capacity and create further problems with the structural integrity, possibly leading to a complete failure of a given rail line. To prevent the unwanted corollaries, the ballast bed has to be periodically cleaned with an appropriate machinery. In this paper the authors investigated the effect of the chemical composition on the physical properties of the ballast excavating chains made of high-manganese steels. The authors focused on the wear mechanism, work hardening ability and hardness in the cross-sections areas. A microstructure analysis was performed as well, and observations revealed divergent morphology of precipitations at the grain boundaries, which influenced the size of austenite grains. The deformation twins formed as a result of operation were noticed in the samples. Research has shown that less carbon and chromium reduces the hardness of cast steel, and it specifically affects the ability to strain hardening. The authors explained the role of adjustments in chemical composition in the operational properties of high-manganese cast steels. It has been shown in the paper that different chemical compositions affect the properties of the alloys, and this causes different types of wear. The high content of chromium increases the hardness of materials before and after plastic deformation hardening, which in the conditions of selector chains results in greater dimensional stability during wear of holes in pin joints and will be more susceptible to abrasive wear in the presence of dusts from the ballast than creep. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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16 pages, 4154 KiB

Open AccessArticle

Effect of Deep Cryogenic Treatment on Wear and Galling Properties of High-Speed Steels

by Patricia Jovičević-Klug, Marko Sedlaček, Matic Jovičević-Klug and Bojan Podgornik

Materials 2021, 14(24), 7561; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14247561 - 09 Dec 2021

Cited by 11 | Viewed by 1757 | Correction

New approaches to improving wear resistance with an affordable and noncomplex technology, such as deep cryogenic treatment, (DCT0), are receiving attention. The aim of this study is to investigate the effect of DCT on the friction and wear performance of high-speed steels. AISI [...] Read more.

New approaches to improving wear resistance with an affordable and noncomplex technology, such as deep cryogenic treatment, (DCT0), are receiving attention. The aim of this study is to investigate the effect of DCT on the friction and wear performance of high-speed steels. AISI M2, AISI M3:2 and AISI M35 were heat-treated under different conditions, and then investigated under dry sliding conditions. Tribological testing involved different contact conditions, prevailing wear mechanisms and loading conditions. The DCT effect on sliding wear resistance depends on HSS steel grade, as well as contact conditions and wear mode, whereas it improves the dynamic impact of the wear and galling resistance. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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14 pages, 6965 KiB

Open AccessArticle

Effect of Temperature on the Tribological Properties of Selected Thermoplastic Materials Cooperating with Aluminium Alloy

by Anita Ptak, Paula Taciak and Wojciech Wieleba

Materials 2021, 14(23), 7318; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14237318 - 29 Nov 2021

Cited by 6 | Viewed by 1558

This article concerns the tribological properties of three selected polymer materials: polyamide PA6, polyethylene PE-HD and polyetheretherketone composite PEEK/BG during sliding against aluminium alloy EN AW-2017A in the presence of hydraulic oil HLP 68. The tests were carried out under contact pressure p [...] Read more.

This article concerns the tribological properties of three selected polymer materials: polyamide PA6, polyethylene PE-HD and polyetheretherketone composite PEEK/BG during sliding against aluminium alloy EN AW-2017A in the presence of hydraulic oil HLP 68. The tests were carried out under contact pressure p of 3.5–11 MPa at ambient temperature T ranging from −20 °C to +20 °C. The dependence of kinetic friction coefficient μ_k on the two parameters was determined through tribological tests carried out using a pin-on-disc tribometer. A five-level central composite rotatable design (CCRD) was adopted for the experiment. All the test results were statistically analysed. The microhardness of the surface of the polymeric material was measured before and after the friction process. The surface was also examined under SEM. Temperature and contact pressure have been found to have a significant effect on the tribological properties of the tested sliding pairs. Relative to the applied friction conditions, the surfaces after friction showed rather heavy signs of wear. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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14 pages, 5110 KiB

Open AccessArticle

Effect of Calcination Temperature on the Phase Composition, Morphology, and Thermal Properties of ZrO₂ and Al₂O₃ Modified with APTES (3-aminopropyltriethoxysilane)

by Damian S. Nakonieczny, Frank Kern, Lukas Dufner, Agnieszka Dubiel, Magdalena Antonowicz and Krzysztof Matus

Materials 2021, 14(21), 6651; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14216651 - 04 Nov 2021

Cited by 24 | Viewed by 2505

This paper describes the effect of calcination temperature on the phase composition, chemical composition, and morphology of ZrO₂ and Al₂O₃ powders modified with 3-aminopropyltriethoxysilane (APTES). Both ceramic powders were modified by etching in piranha solution, neutralization in ammonia water, [...] Read more.

This paper describes the effect of calcination temperature on the phase composition, chemical composition, and morphology of ZrO₂ and Al₂O₃ powders modified with 3-aminopropyltriethoxysilane (APTES). Both ceramic powders were modified by etching in piranha solution, neutralization in ammonia water, reaction with APTES, ultrasonication, and finally calcination at 250, 350, or 450 °C. The obtained modified powders were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, particle size distribution (PSD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS), and thermogravimetric analysis (TGA). Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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21 pages, 7658 KiB

Open AccessArticle

Alumina and Zirconia-Reinforced Polyamide PA-12 Composites for Biomedical Additive Manufacturing

by Damian S. Nakonieczny, Frank Kern, Lukas Dufner, Magdalena Antonowicz and Krzysztof Matus

Materials 2021, 14(20), 6201; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14206201 - 19 Oct 2021

Cited by 22 | Viewed by 3052

This work aimed to prepare a composite with a polyamide (PA) matrix and surface-modified ZrO₂ or Al₂O₃ to be used as ceramic fillers (CFs). Those composites contained 30 wt.% ceramic powder to 70 wt.% polymer. Possible applications for this [...] Read more.

This work aimed to prepare a composite with a polyamide (PA) matrix and surface-modified ZrO₂ or Al₂O₃ to be used as ceramic fillers (CFs). Those composites contained 30 wt.% ceramic powder to 70 wt.% polymer. Possible applications for this type of composite include bioengineering applications especially in the fields of dental prosthetics and orthopaedics. The ceramic fillers were subjected to chemical surface modification with Piranha Solution and suspension in 10 M sodium hydroxide and Si₃N₄ to achieve the highest possible surface development and to introduce additional functional groups. This was to improve the bonding between the CFs and the polymer matrix. Both CFs were examined for particle size distribution (PSD), functional groups (FTIR), chemical composition (XPS), phase composition (XRD), and morphology and chemical composition (SEM/EDS). Filaments were created from the powders prepared in this way and were then used for 3D FDM printing. Samples were subjected to mechanical tests (tensility, hardness) and soaking tests in a high-pressure autoclave in artificial saliva for 14, 21, and 29 days. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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13 pages, 4811 KiB

Open AccessArticle

The Effect of Displacement Amplitude on Fretting Wear Behavior and Damage Mechanism of Alloy 690 in Different Gaseous Atmospheres

by Long Xin, Lanzheng Kang, Weiwei Bian, Mengyang Zhang, Qinglei Jiang and Tetsuo Shoji

Materials 2021, 14(19), 5778; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14195778 - 02 Oct 2021

Cited by 8 | Viewed by 1703

The effect of displacement amplitude on fretting wear behavior and damage mechanisms of alloy 690 in air and nitrogen atmospheres was investigated in detail. The results showed that in air, the friction coefficient gradually increased with the increase in displacement amplitude which conformed [...] Read more.

The effect of displacement amplitude on fretting wear behavior and damage mechanisms of alloy 690 in air and nitrogen atmospheres was investigated in detail. The results showed that in air, the friction coefficient gradually increased with the increase in displacement amplitude which conformed to the universal law. In nitrogen, however, it had the highest point at the displacement amplitude of 60 μm due to very strong adhesion. Whether in air or nitrogen, the wear volume gradually increased with the increase in displacement amplitude. The wear volume in air was larger than that in nitrogen except at 30 μm. At 30 μm, the wear volume in air was slightly smaller. With an increase in displacement amplitude, a transformation of fretting running status between partial slip, mixed stick-slip, and final gross slip occurred along with the change of Ft-D curves from linear, to elliptic, to, finally, parallelogrammical. Correspondingly, the fretting regime changed from a partial slip regime to a mixed regime to a gross slip regime. With the increase in displacement amplitude, the transition from partial slip to gross slip in nitrogen was delayed as compared with in air due to the strong adhesion actuated by low oxygen content in a reducing environment. Whether in air or nitrogen, the competitive relation between fretting-induced fatigue and fretting-induced wear was prominent. The cracking velocity was more rapid than the wear. Fretting-induced fatigue dominated at 30 μm in air but at 30–60 μm in nitrogen. Fretting-induced wear won the competition at 45–90 μm in air but at 75–90 μm in nitrogen. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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20 pages, 12244 KiB

Open AccessArticle

Differences in Wear and Material Integrity of NAO and Low-Steel Brake Pads under Severe Conditions

by Edouard A. T. Davin, Anne-Lise Cristol, Arnaud Beaurain, Philippe Dufrénoy and Neomy Zaquen

Materials 2021, 14(19), 5531; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14195531 - 24 Sep 2021

Cited by 9 | Viewed by 1942

In this study, through severe reduced-scale braking tests, we investigate the wear and integrity of organic matrix brake pads against gray cast iron (GCI) discs. Two prototype pad materials are designed with the aim of representing a typical non-metal NAO and a low-steel [...] Read more.

In this study, through severe reduced-scale braking tests, we investigate the wear and integrity of organic matrix brake pads against gray cast iron (GCI) discs. Two prototype pad materials are designed with the aim of representing a typical non-metal NAO and a low-steel (LS) formulation. The worn surfaces are observed with SEM. The toughness of the pad materials is tested at the raw state and after a heat treatment. During braking, the LS-GCI disc configuration produces heavy wear. The friction parts both keep their macroscopic integrity and wear appears to be homogeneous. The LS pad is mostly covered by a layer of solid oxidized steel. The NAO-GCI disc configuration wears dramatically and cannot reach the end of the test program. The NAO pad suffers many deep cracks. Compacted third body plateaus are scarce and the corresponding disc surface appears to be very heterogeneous. The pad materials both show similar strength at the raw state and similar weakening after heat treatment. However, the NAO material is much more brittle than the LS material in both states, which seems to favor the growth of cracks. The observations of crack faces suggest that long steel fibers in the LS material palliate the brittleness of the matrix, even after heat damage. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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21 pages, 23889 KiB

Open AccessArticle

Friction Behavior of a Textured Surface against Several Materials under Dry and Lubricated Conditions

by Linqing Bai, Jianxin Sun, Pengcheng Zhang and Zulfiqar Ahmad Khan

Materials 2021, 14(18), 5228; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14185228 - 11 Sep 2021

Cited by 10 | Viewed by 1934

This paper reports research on the frictional behavior of a textured surface against several materials under dry and lubricated conditions, and this is aimed to provide design guidelines on the surface texturing for wide-ranging industrial applications. Experiments were performed on a tribo-tester with [...] Read more.

This paper reports research on the frictional behavior of a textured surface against several materials under dry and lubricated conditions, and this is aimed to provide design guidelines on the surface texturing for wide-ranging industrial applications. Experiments were performed on a tribo-tester with the facility of simulating A ball-on-plate model in reciprocating motion under dry, oil-lubricated, and water-lubricated conditions. To study the frictional behavior of textured SiC against various materials, three types of ball-bearing –elements, 52100 steel, silicon nitride (Si₃N₄), and polytetrafluoroethylene (PTFE), were used. Friction and wear performance of an un-textured surface and two types of widely used micro-scale texture surfaces, grooves and circular dimples, were examined and compared. The results demonstrated that the effect of surface textures on friction and wear performance is influenced by texture parameters and the materials of friction pairs. The circular-dimple texture and the groove texture, with certain texture parameters, played a positive role in improving friction and wear performance under specific operating conditions used in this research for SiC–steel and SiC–Si₃N₄ friction pairs; however, there was no friction and wear improvement for the textured SiC–PTFE friction pair. The results of this study offer an understanding and a knowledge base to enhance the performance of bearing elements in complex interacting systems. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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21 pages, 8763 KiB

Open AccessArticle

Modeling the Average and Instantaneous Friction Coefficient of a Disc Brake on the Basis of Bench Tests

by Wojciech Sawczuk, Armando Miguel Rilo Cañás, Dariusz Ulbrich and Jakub Kowalczyk

Materials 2021, 14(16), 4766; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14164766 - 23 Aug 2021

Cited by 9 | Viewed by 2433

This article presents the results of tests conducted on the average and instantaneous friction coefficients of railway vehicle disc brakes. The tests were carried out independently of various states of wear on the friction linings and the brake disc. The requirements of the [...] Read more.

This article presents the results of tests conducted on the average and instantaneous friction coefficients of railway vehicle disc brakes. The tests were carried out independently of various states of wear on the friction linings and the brake disc. The requirements of the International Union of Railways (UIC) regarding the approval of brake linings for use were taken into account. Based on many years of research using a brake bench to test railway disc brakes, the authors developed multiple regression models for the average friction coefficient and fluctuations (tolerances) in the instantaneous friction coefficient and achieved 870 results. The models proposed three types of variables: the input braking parameters (speed, pressure, and mass to be braked), operational parameters (the wear on the friction linings and the brake disc), and design parameters (perforations in the form of holes on the disc surface). The above two models were validated on the basis of 384 brakes, and in subsequent stages a further evaluation was performed. The coefficients were determined to be, respectively, 0.99 for the model of the average friction coefficient and 0.71 for the model of tolerance (fluctuations) of the instantaneous friction coefficient. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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13 pages, 4084 KiB

Open AccessArticle

A Design of Partial Textured Surface on Gear Washers for Reducing Friction and Wear under Low Speed and Heavy Load Conditions

by Yang Liu, Hui Zhang and Guangneng Dong

Materials 2021, 14(16), 4666; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14164666 - 19 Aug 2021

Viewed by 1962

This paper presents the effort to reduce friction and wear of gear washers under low-speed and heavy-load conditions by designing the arrangement of surface textures. The influence of distributional parameters of textures on load-bearing capacity and friction coefficient of gear washers are studied [...] Read more.

This paper presents the effort to reduce friction and wear of gear washers under low-speed and heavy-load conditions by designing the arrangement of surface textures. The influence of distributional parameters of textures on load-bearing capacity and friction coefficient of gear washers are studied numerically to obtain a preferable surface texturing design. Then, experimental tests were carried out to plot the Stribeck curves of the obtained texture arrangement compared with bare surface and another unoptimizable texture distribution arrangement to facilitate the verification of the simulation results. Theoretical predictions illustrate that the annular gear washers with partial surface texturing provide lower friction coefficients than bare washers. Textures having a sector angle of 20°, a coverage angle of 12°, a circumferential number of 8, and a radial number of 6 are selected as the final optimal surface texture distribution design. Experimental results confirm that the obtained texture arrangement moves the Stribeck curve towards the lower left, indicating thickening of oil film thickness and reduction in friction coefficient. In addition, the weight loss caused by wear is also reduced by the optimized texture design. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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16 pages, 8311 KiB

Open AccessArticle

Effect of Lubricant Type on the Friction Behaviours and Surface Topography in Metal Forming of Ti-6Al-4V Titanium Alloy Sheets

by Marcin Szpunar, Tomasz Trzepieciński, Krzysztof Żaba, Robert Ostrowski and Marek Zwolak

Materials 2021, 14(13), 3721; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14133721 - 02 Jul 2021

Cited by 8 | Viewed by 2295

The aim of the research described in this paper is to analyse the synergistic effect of types of synthetic oil and their density on the value of the coefficient of friction (COF) of Ti-6Al-4V titanium alloy sheets. Lubrication performance of commercial synthetic oils [...] Read more.

The aim of the research described in this paper is to analyse the synergistic effect of types of synthetic oil and their density on the value of the coefficient of friction (COF) of Ti-6Al-4V titanium alloy sheets. Lubrication performance of commercial synthetic oils (machine, gear, engine and hydraulic) was tested in a strip draw friction test. The friction tests consisted of pulling a strip specimen between two cylindrical fixed countersamples. The countersamples were placed in the simulator base mounted on a uniaxial tensile test machine. Due to the complex synergistic effect of different strip drawing test parameters on the COF, artificial neural networks were used to find this relationship. In the case of both dry and lubricated conditions, a clear trend was found of a reduction of the coefficient of friction with nominal pressure. Engine oil 10W-40 was found to be the least favourable lubricant in reducing the coefficient of friction of Grade 5 titanium sheets. The two main tribological mechanisms, i.e., galling and ploughing, played the most important role in the friction process on the test sheets. In the range of nominal pressures considered, and with the synthetic oils tested, the most favourable lubrication conditions can be obtained by using a type of oil with a low viscosity index and a high kinematic viscosity. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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11 pages, 4021 KiB

Open AccessArticle

Selected Methods and Applications of Anti-Friction and Anti-Wear Surface Texturing

by Slawomir Wos, Waldemar Koszela and Pawel Pawlus

Materials 2021, 14(12), 3227; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14123227 - 11 Jun 2021

Cited by 6 | Viewed by 2370

The constant development of environmental protection causes the necessity to increase the efficiency of machines. By increasing the efficiency of machines, energy losses can be limited, leading to lower energy consumption. Friction reduction leads to an increase in efficiency and a decrease in [...] Read more.

The constant development of environmental protection causes the necessity to increase the efficiency of machines. By increasing the efficiency of machines, energy losses can be limited, leading to lower energy consumption. Friction reduction leads to an increase in efficiency and a decrease in wear. In this paper, selected surface texturing methods, such as burnishing and abrasive jet machining, with their limitations are presented. Thanks to those processes, various surface textures can be obtained. Examples of applications of these methods for friction and wear reduction are shown. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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12 pages, 4943 KiB

Open AccessEditor’s ChoiceArticle

A Pocket-Textured Surface for Improving the Tribological Properties of Point Contact under Starved Lubrication

by Wei Wang, Wenhan Zhao, Yang Liu, Hui Zhang, Meng Hua, Guangneng Dong, Hon-Yuen Tam and Kwai-Sang Chin

Materials 2021, 14(7), 1789; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14071789 - 05 Apr 2021

Cited by 5 | Viewed by 2278

This paper reports a novel pocket-textured surface for improving the tribological properties of point contact under starved lubrication by possibly storing and releasing oil, and homogenizing the surface contact pressure. The ball-on-disk experimental results confirmed the coefficient of friction (COF) and wear reduction [...] Read more.

This paper reports a novel pocket-textured surface for improving the tribological properties of point contact under starved lubrication by possibly storing and releasing oil, and homogenizing the surface contact pressure. The ball-on-disk experimental results confirmed the coefficient of friction (COF) and wear reduction effect of such pocket-texturing. The maximum reduction rate was 40% compared with a flat surface under the same operating conditions. Analyses on experimental results attributed the oil storage effect and enhanced the secondary lubrication effect within the starved lubrication state, to become the main mechanism. In addition, the plate elasticity and the Hertzian contact principles were employed to estimate the pressure and the load acting on the surface. The experimental results and numerical analysis substantiated the design of pocket-textured surface, making it likely to enlarge about 50% of contact surface and to reduce 90% of equivalent stress in comparison to those of conventional surfaces. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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15 pages, 3347 KiB

Open AccessArticle

How Good Are the Performances of Graphene and Boron Nitride Against the Wear of Copper?

by Min Cheol Kang, Hai Woong Park and Arnaud Caron

Materials 2021, 14(5), 1148; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14051148 - 28 Feb 2021

Cited by 2 | Viewed by 1764

We investigate the copper-wear-protective effects of graphene and boron nitride in single asperity sliding contact with a stiff diamond-coated atomic force microscopy (AFM)-tip. We find that both graphene and boron nitride retard the onset of wear of copper. The retardment of wear is [...] Read more.

We investigate the copper-wear-protective effects of graphene and boron nitride in single asperity sliding contact with a stiff diamond-coated atomic force microscopy (AFM)-tip. We find that both graphene and boron nitride retard the onset of wear of copper. The retardment of wear is larger with boron nitride than with graphene, which we explain based on their respective out-of-plane stiffnesses. The wear protective effect of boron nitride comes, however, at a price. The out-of-plane stiffness of two-dimensional materials also determines their friction coefficient in a wear-less friction regime. In this regime, a higher out-of-plane stiffness results in larger friction forces. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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15 pages, 15062 KiB

Open AccessArticle

Stereometric and Tribometric Studies of Polymeric Pin and Ceramic Plate Friction Pair Components

by Magdalena Niemczewska-Wójcik and Artur Wójcik

Materials 2021, 14(4), 839; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14040839 - 09 Feb 2021

Cited by 5 | Viewed by 1739

Two complementary approaches should be used for the full characterisation of friction pair components. The first approach consists of stereometric studies of machined as well as worn surface topography of the friction components with multiple measurement methods used. The second approach, tribometric studies, [...] Read more.

Two complementary approaches should be used for the full characterisation of friction pair components. The first approach consists of stereometric studies of machined as well as worn surface topography of the friction components with multiple measurement methods used. The second approach, tribometric studies, enables the tribological characteristics of the friction pair. This work presents the complete characterisation of polymeric pin and ceramic plate friction pair components based on studies with the use of three research instruments: an interference microscope, a scanning electron microscope and a tribological tester. The results of the studies showed that the same treatment conditions used for different but similar ceramic materials did not provide exactly the same characteristics of both the machined and worn surface topography. Moreover, the results showed that the material properties and machined surface topography of the ceramic component significantly affected the friction coefficient and linear wear as well as the wear intensity of the polymeric component. Connecting the two approaches, stereometric studies and tribometric studies, allowed for a better identification of the wear mechanism of the polymeric pin (i.e., abrasion, fatigue and adhesion wear) and the kind of wear products (polymeric material). Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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23 pages, 11957 KiB

Open AccessArticle

The Impact of the Lubricant Dose on the Reduction of Wear Dies Used in the Forging Process of the Valve Forging

by Łukasz Dworzak, Marek Hawryluk and Marta Janik

Materials 2021, 14(1), 212; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14010212 - 04 Jan 2021

Cited by 9 | Viewed by 3122

The paper presents the results of research on the influence of the settings of lubrication and cooling system parameters (solenoid valve opening time and lubricant feed pressure in terms of its quantity) in order to select the optimal lubricating conditions and thus reduce [...] Read more.

The paper presents the results of research on the influence of the settings of lubrication and cooling system parameters (solenoid valve opening time and lubricant feed pressure in terms of its quantity) in order to select the optimal lubricating conditions and thus reduce the wear of the dies used in the first forging operation of the valve forging made of high-nickel steel. Based on the observation of lubrication in the industrial process, it was found that a significant part of the lubricant fails to reach the die cavity, reaching the outside of it, which causes die wear due to seizure resulting from adhesion of the forging material to the tool surface as well as high lubricant consumption and dirt in the press chamber. The authors proposed their own mobile lubricating and cooling system, which allows for a wide range of adjustments and provided with automatic cleaning procedures of the entire system, unlike the fixed lubrication system used so far in the industrial process. First, tests were carried out in laboratory conditions to determine the highest wettability and the lubricant remaining inside the tool cavity. These tests determined the lubrication system parameter settings that ensured that the greatest amount of lubricant remains in the cold die cavity without the forging process. Then, to verify the obtained results, tests were carried out in the industrial process of hot die forging of valve forgings for short production runs of up to 500 forgings. The results were compared with the measurement of changes in the geometry of tools and forgings based on 3D scanning and surface topography analysis with the use of SEM (Scanning Electron Microscope). For the best results (the variant of the setting of the dose and the time of exposure to lubricant), the forging process was carried out with the use of a new tool up to the maximum service life. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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17 pages, 10002 KiB

Open AccessArticle

The Wear on Roller Press Rollers Made of 20Cr4/1.7027 Steel under Conditions of Copper Concentrate Briquetting

by Michał Bembenek, Janusz Krawczyk and Krzysztof Pańcikiewicz

Materials 2020, 13(24), 5782; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13245782 - 17 Dec 2020

Cited by 13 | Viewed by 2601

This paper defines the wear process of rollers made of 20Cr4. Rollers with a diameter of 1000 mm were installed in a roller press used for the production of drop-shaped briquettes and the copper concentrate was briquetted for 1100 h. Three-dimensional (3D) geometry [...] Read more.

This paper defines the wear process of rollers made of 20Cr4. Rollers with a diameter of 1000 mm were installed in a roller press used for the production of drop-shaped briquettes and the copper concentrate was briquetted for 1100 h. Three-dimensional (3D) geometry analysis, metallographic analysis, macroscopy, scanning electron microscopy, as well as hardness measurements were performed. It was observed that the working surface was non-uniformly worn. The smallest wear affects the molding cavities situated on the outermost edges of the ring. The wear increases as the center of the ring is approximated, and it reaches its maximum at the middle of the ring. The molding cavities also wear asymmetrically. For the shape considered in this study, the lower part of a cavity is subject to a higher wear rate. We found that the material of the working ring was carburized, but its hardness was significantly lower than required. The roller ring microstructure changes depended on the distance from the cavity’s face. An investigation of the wear mechanisms showed different types of abrasive wear, corrosive processes, and plastic deformation. The exact type and course of wear were described, depending on the location on the working surface. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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20 pages, 11526 KiB

Open AccessArticle

The Effect of Surface Texture on Lubricated Fretting

by Agnieszka Lenart, Pawel Pawlus, Andrzej Dzierwa, Slawomir Wos and Rafal Reizer

Materials 2020, 13(21), 4886; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13214886 - 30 Oct 2020

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Experiments were conducted using an Optimol SRV5 tester in lubricated friction conditions. Steel balls from 100Cr6 material of 60 HRC hardness were placed in contact with 42CrMo4 steel discs of 47 HRC hardness and diversified surface textures. Tests were carried out at a [...] Read more.

Experiments were conducted using an Optimol SRV5 tester in lubricated friction conditions. Steel balls from 100Cr6 material of 60 HRC hardness were placed in contact with 42CrMo4 steel discs of 47 HRC hardness and diversified surface textures. Tests were carried out at a 25–40% relative humidity. The ball diameter was 10 mm, the amplitude of oscillations was set to 0.1 mm, and the frequency was set to 80 Hz. Tests were performed at smaller (45 N) and higher (100 N) normal loads and at smaller (30 °C) and higher (90 °C) temperatures. During each test, the normal load and temperature were kept constant. We found that the disc surface texture had significant effects on the friction and wear under lubricated conditions. When a lower normal load was applied, the coefficient of friction and wear volumes were smaller for bigger disc surface heights. However, for a larger normal load a higher roughness corresponded to a larger coefficient of friction. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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15 pages, 6337 KiB

Open AccessArticle

Dry Rolling/Sliding Wear of Bainitic Rail Steels under Different Contact Stresses and Slip Ratios

by Jiapeng Liu, Yingqi Li, Yinhua Zhang, Yue Hu, Lubing Shi, Haohao Ding, Wenjian Wang, Fengshou Liu, Shaobo Zhou and Tong Shi

Materials 2020, 13(20), 4678; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13204678 - 20 Oct 2020

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This study aims to deeply understand the effect of contact stress and slip ratio on wear performances of bainitic rail steels. The results showed that the wear loss increased as the contact stress and slip ratio increased. Based on the surface damage morphology [...] Read more.

This study aims to deeply understand the effect of contact stress and slip ratio on wear performances of bainitic rail steels. The results showed that the wear loss increased as the contact stress and slip ratio increased. Based on the surface damage morphology and microstructural analyses, it revealed that the rolling contact fatigue wear mechanism played a significant role under the low slip ratio, but the dominant wear mechanism transferred to the abrasive wear at the high slip ratio. Meanwhile, the bainitic steel specifically presented worse wear resistance under the abrasive wear mode. Compared with the influence of a slip ratio, the increase in contact stress led to severer plastic flows and contributed to the propagation of cracks. In addition, the contact stress and slip ratio had the opposite effect on the friction coefficient, that is, the friction coefficient of bainitic steels behaved the inverse proportion with the contact stress, but positive proportion with the slip ratio. At last, the increase in slip ratio had more significant effect on the reduction of retained austenite (RA) than the enlargement of contact stress due to the fact that the RA would probably be removed before the martensitic transformation occurred under the abrasive wear mechanism. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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27 pages, 11530 KiB

Open AccessArticle

A Numerical Wear Simulation Method of Reciprocating Seals with a Textured Rod

by Hongliang Ran, Di Liu and Shaoping Wang

Materials 2020, 13(19), 4458; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13194458 - 08 Oct 2020

Cited by 3 | Viewed by 2603

Reciprocating rod seals are widely used in the hydraulic actuator to prevent the leakage of fluid. The sealing lip profile changes with the seal wear, resulting in an increase in the leakage. A texturing rod changes the lubrication characteristics of the seal, so [...] Read more.

Reciprocating rod seals are widely used in the hydraulic actuator to prevent the leakage of fluid. The sealing lip profile changes with the seal wear, resulting in an increase in the leakage. A texturing rod changes the lubrication characteristics of the seal, so it affects the wear and leakage of the seal. A numerical simulation method is proposed to investigate the wear of the hydraulic reciprocating seal with textured rods. Several kinds of macro-cavity textures on the rod surface, including circle, square and triangle shapes, have been simulated and discussed. The effects of three shape parameters including area ratio, depth, and ratio of the axial length to the circumferential length on the seal wear are analyzed in detail. The texturing rod slightly increases the seal wear, but decreases the seal leakage. When the rod speed is increasing, the wear time rates of the seal increase, while the wear distance rates decrease, regardless of the texture shapes. When the texture area ratio is increasing, the wear of the reciprocating seal increases. Seal wear decreases with an increasing texture depth during the outstroke, however, it increases during the instroke. The ratio of the axial length of the macro-cavity to the circumferential length has no effect on the seal wear. Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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3 pages, 638 KiB

Open AccessCorrection

Correction: Jovičević-Klug et al. Effect of Deep Cryogenic Treatment on Wear and Galling Properties of High-Speed Steels. Materials 2021, 14, 7561

by Patricia Jovičević-Klug, Marko Sedlaček, Matic Jovičević-Klug and Bojan Podgornik

Materials 2022, 15(20), 7218; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15207218 - 17 Oct 2022

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In Sections 3 [...] Full article

(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)

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