Friction and abrasive wear behaviour of Al^sub 2^O^sub 3^-13TiO^sub 2^ and Al^sub 2^O^sub 3^-13TiO^sub 2^+Ni Graphite coatings

The friction and abrasive wear of plasma sprayed Al2O3-13TiO2 coating, with and without the addition of graphite was investigated. XPS analysis was used to determine the extent of γ-α Al2O3 phase transformation after wear. γ-α Al2O3 phase transformation had different influence on friction and wear of coatings. Al2O3-13TiO2+15% Ni Graphite coating exhibited lower coefficient of friction and lower abrasive wear rates than Al2O3-13TiO2 coating; the magnitude of decrease was dependent on load. The better abrasive wear resistance and lower coefficient of friction of Al2O3-13TiO2+15% Ni Graphite coating was due to the synergistic effect of self-lubricating film of graphite and tribochemical reactions. The severity of contact could identify transitions in abrasive wear rates, operating wear mechanisms and associated failure modes.