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Study on the effect of milling parameters on HE-MA nanostructured Al-Graphene cermet particles
Jagannadh V.S.N. Sripada
* ,
Megil F. Gallant
,
Gobinda C. Saha
*
1  University of New Brunswick, Fredericton
Published: 14 March 2019 by MDPI in 1st Coatings and Interfaces Web Conference session Corrosion and Surface Protection
https://doi.org/10.3390/ciwc2019-06160
Abstract:

Nanocrystalline grains have proven to be excellent reinforcing elements in nanostructured particulate materials. On the other hand, carbon allotropes, especially graphene and carbon nanotube (CNT), exhibit elastic modulus in the range of 1 TPa (theoretical) and tensile strength in multiple orders greater than that of steel. This study aims at synthesizing high-strength nanostructured ceramic-metallic (cermet) particle feedstock in a high-energy mechanical alloying (HE-MA) process based on an Al-graphene composite comprehensive design-of-experiments (DoE). The goal is to optimize milling process parameters, including milling time, batch composition, ball-to-power (BPR) ratio, and milling agent, for the particles to be eventually fed into a high-pressure cold spray coatings development. The milled powders are characterized using SEM, EDS, XRD, and laser particle diffractometer to study the morphology and microstructure, elemental composition, grain size and crystal orientation, and particle size distribution (PSD), respectively. Results show it was possible to attain required structure and PSD at a 10:1 BPR with 5-mm diameter ball, at 1200 rpm, and 4 h of milling.

Keywords: Al-graphene nanocomposite; high-energy mechanical alloying; microstructure characterization
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Comments on this paper
Henry Hitt
1 April 2019
Replacing the catalyst can definitely know about the amount of stored energy
Works that nanocrystalline grains can be excellent reinforcing elements in nanostructured solid materials. There are studies that graphene and carbon nanotubes (CNTs) demonstrate a modulus of elasticity in the range of 1 TPa (theoretical) and tensile strength several times higher than that of steel. Your research included the synthesis of high-strength nano-structured raw materials from metal-ceramic (metal-ceramic) particles in the process of high-energy mechanical doping (HE-MA). In this case, the complex scheme of experiments (DoE) with a composite based on Al-graphene served as the basis for carrying out this interesting study. The goal may also be optimization of grinding process parameters, including grinding time, batch composition, a ball-force ratio (BPR) and grinding agent, for particles that will ultimately be fed to the development of high-pressure cold spray coatings. It seems insufficient to characterize ground powders using SEM, EDS, XRD and a laser diffractometer to study morphology and microstructure, elemental composition, grain size and orientation of crystals, as well as particle size distribution (PSD), respectively. Although the results show that it was possible to obtain the required structure and PSD at 10: 1 BPR with a ball with a diameter of 5 mm, at 1200 rpm and 4 hours of grinding, however, these are not all the conclusions that can be obtained from the work and the samples obtained. When located in ball mills, the material to be ground accumulates kinetic energy, which is reported to it by the ceramic balls for grinding. This energy can be very high and it can either contribute to the combination of the final composition obtained by mechanical doping, or vice versa hinder. During grinding, this energy is stored up by the samples much more actively if this treatment is carried out in a vacuum or in an inert gas (argon) atmosphere. To measure such energy is quite easy by the participation of the sample in any redox reaction, where catalysts are used. Replacing the catalyst can definitely know about the amount of stored energy.


 
 
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