This study aims to investigate the mechanical, wear and corrosion performances of TiC reinforced AZ91 matrix composites. AZ91 alloy and AZ91/TiC composites with different weight fractions of 10, 20 and 30 (wt%) were fabricated by powder metallurgy incorporating hot pressing. Microstructure characterization shows that partial agglomeration of particles is present especially in AZ91/30 wt% TiC composite. The addition of TiC led to significant improvement in hardness and wear resistance. Observed wear mechanism is abrasive. As compared with AZ91, compressive yield strength and ultimate compressive strength of the composites were also significantly improved. On the other hand, corrosion rate increased with the addition of TiC particles by virtue of presence of the galvanic reactions.
The present study aims to produce graphene nanoplatelet-coated B4C ceramic particle using semi-powder method and to investigate the effect of graphene nanoplatelets on wear and corrosion performance of Al–Si-based metal matrix hybrid composites. For this purpose, first graphene nanoplatelets at different ratios (0.25, 0.5, and 1 vol.%) were coated to the surfaces of B4C particles and then the Al–Si alloy was infiltrated into the reinforcements by gas pressure infiltration method. The characterization of graphene nanoplatelet-coated B4C powders and its composites was carried out by X-ray diffraction, differential scanning calorimetry, scanning electron microscope, and transmission electron microscope analysis. Tribological properties were investigated by reciprocating ball-on-flat method under three different loads (10–20–40 N) in a dry environment. The corrosion resistance was carried out with Tafel polarization method in 3.5% NaCl solution. Characterization results show that graphene coated on the B4C surface was successfully achieved by semi-powder method. After infiltration process, a new phase formation was not observed, but porosity increased with the increase of graphene content. When the boron carbide surface was coated with 0.5vol.% graphene, it was determined that the specific wear resistance increased by 55% and the corrosion resistance decreased by 12%.
12 July 2019 in Metals and Materials International
The present study aims to investigate the effect of Multi-Wall Carbon Nanotube on dry sliding and corrosive wear performance of pure magnesium. Multi-wall carbon nanotube reinforced composites with different weight fractions (0.25 wt.% and 0.5 wt.%) were fabricated by semi powder metallurgy. Hardness test was performed for all samples. To evaluate wear performance of the samples, three different loads (10 N, 20 N, and 40 N) were applied at the room temperature in both dry and 3.5 wt.% NaCl corrosive environments. Worn surfaces and microstructures of the samples were characterized using Scanning Electron Microscope. Results show that carbon nanotubes embedded in the matrix without any macro-defects. The hardness of pure magnesium was improved with the addition of multi-wall carbon nanotube considerably. 0.5 wt.% multi-wall carbon nanotube reinforced composite exhibited best wear performance both in dry and corrosive conditions.
In this study, graphene nanoplatelets (0.25 and 0.5 wt-%) reinforced aluminium matrix composites were synthesised. Microstructures of composites were investigated by X-ray diffraction, scanning electron microscope and transmission electron microscope. Hardness was measured according to the Vickers test method. Tensile tests were performed at both room (25°C) and elevated temperatures (150°C and 250°C). Results showed that hardness was improved with direct addition of graphene. Microstructure of composites was free of macro defects. Yield and tensile strength behaviours of pure aluminium were increased with the addition of graphene especially at room temperature. Graphene-reinforced samples have higher compressive residual stress. From the outer surface to inner surface, transition from compressive to tensile residual stress was observed for samples.
1 February 2018 in Fullerenes, Nanotubes and Carbon Nanostructures
The present study aims to fabricate fullerene (C60) reinforced magnesium matrix composite via semi powder metallurgy in hot press system under high purity argon atmosphere. Improvement of wear resistance of pure magnesium with the addition of fullerene is also aimed with this study. Hardness and wear tests at room temperature were performed to investigate the mechanical effect of fullerene nanoparticles. Microstructures of fabricated composites were characterized using Scanning Electron Microscope (SEM). Results clearly show that hardness performance was improved up to 0.5 wt. % fullerene addition directly. A uniform distribution was also achieved according to the mapping and line EDX analysis for the lower content of fullerene. Agglomeration of fullerene was observed for 1 wt. % reinforced composite. Wear performances of pure magnesium were also improved when harder fullerene reinforcements incorporated into the matrix. Abrasion and oxidation were main wear mechanism for unreinforced and fullerene reinforced composites. Enhancement of hardness and wear performances might be attributed to the high specific surface area of fullerene and achievement of uniform distribution of reinforcement in magnesium matrix.