Effects of atmospheric conditions on mechanical mixed layer formation and wear behaviour in A356–15 vol.-%SiC p composite

Dry sliding wear tests have been carried out on A356–15 vol.-%SiC_p metal matrix composite to evaluate the effects of argon and oxygen atmospheres on mechanical mixed layer (MML) formation and wear behaviour. The wear rate of the composite under an oxygen atmosphere is higher by one order of magnitude than that under an argon atmosphere. The formation of the MML depends strongly on the atmospheric conditions. The MML formed under argon is found to be more stable and results in a lower wear rate within the parametric regime, compared with that formed under an oxygen atmosphere. The mechanism of material removal under an argon atmosphere is by delamination. Under the oxygen atmosphere the MML is highly unstable, and material removal is by severe two and three body abrasion at low load and low sliding velocity. At high load and high sliding velocity, the material removal mechanism is by delamination.