Hot-Pressing of Ti(C, N)-Cr₃C₂-Al₂O₃ Mixed Powder

Abstract

Cutting tools of Ti(C, N)-Cr₃C₂ ceramics have better wear resistance than those of TiC-TiN cermets and WC-Co alloy tools for carbon steel. Sintered bodies of this system have the fracture toughness K_1C of 2.5MPa⋅m^1/2. Higher fracture toughness is necessary for wider application. Therefore, addition of Al₂O₃ to Ti(C, N)-Cr₃C₂ system is tried. The main results are as follows:
(1) Ti(C, N)-5wt% Cr₃C₂-Al₂O₃ sintered bodies containing 30-50wt% Al₂O₃ have the porosity of 0.1vol%, K_1C of 4.2MPa⋅m^1/2, transverse rupture strength of about 700MPa, and Vickers hardness of 1850Hv.
(2) These sintered bodies consist of (Ti, Cr) (C, N, O) and Al₂O₃.
(3) It is thought that high K_1C is due to high toughness of Al₂O₃ grains and grain boundaries between (Ti, Cr) (C, N, O) and Al₂O₃.