Tribological Properties of Ni₃Al Matrix Self-lubricating Composites

The Ni₃Al matrix self-lubricating composites were fabricated by powder metallurgy technique. The tribological properties of the Ni₃Al matrix self-lubricating composites were investigated under different conditions using a HT-1000 type ball on disc high temperature tribometer. The results show that the composites had good self-lubricating properties from 20 ℃ to 1 000 ℃, and the friction coefficient ranged from 0.24 to 0.43. The friction coefficient was the lowest (from 0.24 to 0.29) at a load of 5 N and temperatures from 20 ℃ to 400 ℃, but high friction coefficient (from 0.39 to 0.41) at temperature higher than 600 ℃. The composites had low and steady friction coefficient (0.28~0.31) at a load of 20 N from 20 ℃ to 1 000 ℃. The excellent high-temperature tribological properties of Ni₃Al matrix self-lubricating composites can be attributed to synergtic lubricating effect of Ag, fluorides, oxides and molybdates on the frictional surface.