Correlation between microstructure and wear behavior of AZX915 Mg-alloy reinforced with 12 wt%TiC particles by stir-casting process

The present work concerns with correlation between microstructure and wear behavior of AZX915 Mg-alloy reinforced with 12 wt%of TiC particles by stir-casting process.Dry sliding tests were performed under ambient environment by using a pin-on-disc(EN8 steel)configuration with a normal load of 50 N at a constant sliding speed of 2.50 ms^(−1).While as-cast composite experienced delamination wear,heat treated composite suffered from delamination and oxidation wear during dry sliding contact.Moreover,the heat treated composite exhibited lower friction and higher wear rate as compared to the as-cast composite.Friction and wear behavior were correlated with microstructures based on the concept of oxidation tendency and crack nucleation/propagation.Further,a schematic model has been proposed illustrating wear mechanisms from the point of view of subsurface microstructural evolution of the AZX915-TiCp composite.

Tribological behavior comparisons of high chromium stainless and mild steels against high-speed steel and ceramics at high temperatures

High-temperature tribology,which is often involved during hot metal forming,is controlled via oxidation on a rubbing surface.However,for high chromium stainless steel(ST),where oxidation is strongly inhibited,the effect of counterface materials on tribological behavior is yet to be elucidated.In this study,the effects of counterfaces on the tribological behavior of 253MA ST and mild steel(MS)are investigated via a ball-on-disc test at 900°C using a 20 N load.The results reveal that high-speed steel(HSS)experiences severe abrasive wear with MS and causes severe sticking problems with ST.Si3N4 and SiC present substantially stronger abrasive wear resistance than HSS with MS,and the friction coefficients are dependent on the type of ceramic.Both ceramics can facilitate the establishment of a thick tribo-oxide layer(>3μm)on ST to prevent sticking;however,this is accompanied by severe pull-out and fracture wear.The effects of the counterface on the mechanical properties of the tribo-oxide layer,near-surface transformation,and the responses of the tribo-oxide layer to friction and wear are discussed.This study contributes to the understanding of interfacial tribological behaviors when different types of tools are used on MS and ST.