EFFECT OF MICROSTRUCTURE ON MECHANICAL-PROPERTIES AND CUTTING PERFORMANCE OF AL2O3-TI(C, N) CERAMICS

The effect of the microstructure on the mechanical properties and the cutting performance of Al2O3-30 wt%Ti(C, N) ceramics was studied. Three Al2O3-Ti(C, N) ceramics with average Al2O3 grain size of 1.6-1.9-mu-m, 1.0-1.2-mu-m and 0.7-1.0-mu-m were obtained by presintering and HIPing. Large Ti(C, N) grains were mainly distributed at the grain boundaries and prevented the grain growth of Al2O3 grains. But in the ceramics with large Al2O3 grains, some fine Ti(C, N) particles were dispersed within Al2O3 grains. As microstructure became finer, the bending strength increased and the fracture toughness K(IC) decreased. In the cutting test of tool steel (SKD11), the flank wear became less and the tool life became longer as the grain size decreased and N/(C + N) ratio in Al2O3-Ti(C, N) increased.