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Volume 1, June
 
 

Powders, Volume 1, Issue 1 (March 2022) – 5 articles

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15 pages, 3135 KiB  
Article
Infrared Spectroscopy Studies of Aluminum Oxide and Metallic Aluminum Powders, Part I: Thermal Dehydration and Decomposition
by Bellamarie Ludwig and Taryn T. Burke
Powders 2022, 1(1), 47-61; https://0-doi-org.brum.beds.ac.uk/10.3390/powders1010005 - 10 Mar 2022
Cited by 9 | Viewed by 3639
Abstract
In this work, we study three aluminum oxides (alpha, gamma, boehmite) and various oxidized metallic aluminum powders to observe their dehydration and decomposition behavior using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and scanning electron microscopy (SEM). We find that a [...] Read more.
In this work, we study three aluminum oxides (alpha, gamma, boehmite) and various oxidized metallic aluminum powders to observe their dehydration and decomposition behavior using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and scanning electron microscopy (SEM). We find that a temperature increase to the aluminum oxides (aluminas) reduces physically adsorbed water molecules to reveal the presence of hydroxyl groups. All three aluminas contained bridged hydroxyls located at 3670 cm−1; we found additional surface hydroxyls, which varied based on the oxidation state of the aluminum atom. Oxidized metallic aluminum powders that were aged resulted in similar behavior; however, the results differed depending on the method of aging. We find that naturally aged aluminum (NA-Al) powders with heavy oxidation in the form of the tri-hydroxide decomposed and did not reveal any detectable surface hydroxyl peaks. When aged using artificial methods (AA-Al), we find both surface hydroxyls, including bridged hydroxyls at 3670, 3700, and 3730 cm−1, and a remaining boehmite-like surface. These results show that metallic aluminum powders can be tailored for specific applications, regardless of age. It also elucidates different ways to pre-process the powders to control the surface oxide layer, corroborated by comparison with the models oxides studied herein. Full article
(This article belongs to the Special Issue Feature Papers in Powders)
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14 pages, 18666 KiB  
Article
Sugar as an Analogue for Snow in Penetration Testing: A Preliminary Comparison
by Adrian B. McCallum, Damon Kent and Denham Lee
Powders 2022, 1(1), 33-46; https://0-doi-org.brum.beds.ac.uk/10.3390/powders1010004 - 24 Feb 2022
Viewed by 2148
Abstract
Snow is a sintered matrix of ice, the strength of which is determined by the number and size of bonds between ice grains. However, because snow is a thermally unstable material, it is problematic to transport and store samples for accurate ex situ [...] Read more.
Snow is a sintered matrix of ice, the strength of which is determined by the number and size of bonds between ice grains. However, because snow is a thermally unstable material, it is problematic to transport and store samples for accurate ex situ testing of mechanical behaviour. As an analogue for snow, we examined the sintering behaviour of different types of granular sugar at different humidities over different temporal periods and then assessed the extent of sintering and resistance to penetration of these samples. Like snow, increased sintering occurs in sugar over time. Sintering extent and rate are affected by the humidity environment and penetration resistance generally increases after increased sintering time. This preliminary examination suggests that in the absence of snow testing facilities, humidity-controlled sintered sugar may serve as a valuable proxy for examining the temporal variation of penetration resistance in snow. Full article
(This article belongs to the Special Issue Feature Papers in Powders)
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15 pages, 8896 KiB  
Article
A Carbon-Free Way for Obtaining Nanoscale Silicon
by Nikolay Lyakhov, Tatiana Grigoreva, Tatiana Talako, Tatyana Udalova, Sergey Vosmerikov and Evgeniya Devyatkina
Powders 2022, 1(1), 18-32; https://0-doi-org.brum.beds.ac.uk/10.3390/powders1010003 - 17 Feb 2022
Cited by 2 | Viewed by 2073
Abstract
The nanosized silicon powder has been produced by reduction of silica with magnesium in an argon medium using both the mechanically activated self-propagating high-temperature synthesis and the direct mechanochemical synthesis and has been investigated by X-ray phase analysis, Infrared spectroscopy, electron scanning microscopy, [...] Read more.
The nanosized silicon powder has been produced by reduction of silica with magnesium in an argon medium using both the mechanically activated self-propagating high-temperature synthesis and the direct mechanochemical synthesis and has been investigated by X-ray phase analysis, Infrared spectroscopy, electron scanning microscopy, and energy dispersive X-ray spectroscopy. The optimal Mg:SiO2 ratio has been found to provide the minimum content of contaminant impurities of magnesium silicide and silicate in mechanically activated self-propagating high-temperature synthesis. For the first time, direct mechanochemical synthesis of Si via reduction of silica with magnesium has been implemented. Optimal component ratio and mechanical activation parameters have been determined, yielding Si/MgO composites without impurity phases (magnesium silicide and silicate). A purification procedure has been proposed for separating silicon obtained from magnesium oxide and other impurity phases. The ratio of initial components has been determined, at which purified silicon has the least amount of impurities. The particle size of silicon powder obtained was 50–80 nm for the mechanically activated self-propagating high-temperature synthesis, and 30–50 nm for the direct mechanochemical synthesis. Full article
(This article belongs to the Special Issue Feature Papers in Powders)
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15 pages, 3018 KiB  
Article
Mechanical, Corrosion, and Ion Release Studies of Ti-34Nb-6Sn Alloy with Comparable to the Bone Elastic Modulus by Powder Metallurgy Method
by Mariana Correa-Rossi, Liliana Romero-Resendiz, Daniel Leal-Bayerlein, Ana Liz Garcia-Alves, Francisco Segovia-López and Vicente Amigó-Borrás
Powders 2022, 1(1), 3-17; https://0-doi-org.brum.beds.ac.uk/10.3390/powders1010002 - 25 Jan 2022
Cited by 14 | Viewed by 2735
Abstract
The development of a Ti-34Nb-6Sn alloy by the powder metallurgy method, employing two different compaction conditions, A (100 MPa) and B (200 MPa), was carried out. To evaluate the feasibility of the Ti-34Nb-6Sn alloy as an implant biomaterial, microstructural and mechanical characterizations, as [...] Read more.
The development of a Ti-34Nb-6Sn alloy by the powder metallurgy method, employing two different compaction conditions, A (100 MPa) and B (200 MPa), was carried out. To evaluate the feasibility of the Ti-34Nb-6Sn alloy as an implant biomaterial, microstructural and mechanical characterizations, as well as corrosion susceptibility and ion release tests, were performed. Results indicated microstructures dominated by the presence of β-Ti phase and a lower percentage of α-Ti and Nb phases. The porosity percentage decreased when the compaction pressure increased. Both conditions presented a good match between the elastic moduli of the alloy (14.0 to 18.8 GPa) and that reported for the bone tissue. The Ti, Nb and Sn ions released for both compaction conditions were within the acceptable ranges for the human body. Condition B showed higher corrosion resistance in comparison with condition A. Based on the obtained results, the produced porous Ti-34Nb-6Sn alloys are feasible materials for orthopedic implant applications. Full article
(This article belongs to the Special Issue Feature Papers in Powders)
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2 pages, 1028 KiB  
Editorial
Powders—A New Open Access Journal for Powder and Particle Studies
by Paul F. Luckham
Powders 2022, 1(1), 1-2; https://0-doi-org.brum.beds.ac.uk/10.3390/powders1010001 - 18 Nov 2021
Viewed by 2034
Abstract
Powders and particles are ubiquitous in our daily lives and are of course present in variety of diverse products and in the majority of industries; thus, the functionality of powders is very diverse [...] Full article
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