Tribological Characterization of Al2O3/TiC/Ni Functionally Graded Materials.

Symmetrically graded materials in the systems of Al2O3/TiC/Ni with three different outer layers of the Al2O3, Al2O3-15vol%SiC, and Al2O3-20vol%a(WC-15wt%Co) were sintered by SHS/HIP. Strong compressive-residual-stresses were induced in the outer layers resulting in enhancement of their surface toughness, hardness and strength. These FGMs showed superior wear resistance comparing with the monolithic Al2O3 ceramics. The Al2O3-20vol%(WC-15wt%co)/TiC/Ni system showed the lowest friction coefficients of 0.28. However, the friction coefficients of these FGMs increased with temperature and the worn parts were rough.