Oxidation Behavior of TiCN-HfC-WC Cermet at High Temperature.

In this investigation, with increasing oxidation time or temperature, the observed mass gain abided by the parabolic law. TiCN-HfC-WC cermet contained different layers, with each one having a unique composition. Thermal fracture occurred in the sub-oxidation layer, and the flexural strength gradually decreased from 1270.6 MPa to 149.9 MPa. Ther-mal stress equations for calculating the radial, circumferential, and axial stresses were es-tablished. The thermal stress differences between neighboring layers determined the ther-mal fracture; when they were zero, the physical parameters of the layers were related, which could be used to guide cermet material design.