Fabrication and mechanical properties of Al2O3 BN/TiC/Ni FGMs
Higuchi Koji; Lin Junshan; Miyamoto Yoshinari; Hirota Ken; Yamaguchi Osamu; Umeda Kazunori; Tanaka Akihiro; Yamamoto Masaaki; Tanaka Ryohei
Abstract:Symmetrically graded materials of the Al2O3 BN/TiC/Ni were fabricated by SHS/HIP. High residual compressive stresses were produced in the outer layer due to the thermal expansion mismatch between the outer Al2O3 BN ceramic and the inner TiC/Ni cermet layer. The dispersion of BN in the Al2O3 layer increased the residual stress to higher levels than that induced in the Al2O3/TiC/Ni system. The BN has the layer structure with cleavage faces. The tribological properties of the outer Al2O3 BN layer were investigated at room temperature and 500 degree C in air. The friction coefficient of the outer layer was lower than that of monolithic Al2O3, especially at 500 degree C. The residual compressive stress was found to improve wear resistance of the surface layer. Key Words:Al2O3-BN/TiC/Ni, symmetrically graded structure, residual compressive stress, BN