Investigation of the Mechanism of High Temperature Oxidation of TIC-5VC-18NICR-2ALN Cermets

摘要

The oxidation resistance of the TiC-5VC-18NiCr-2AlN cermet in air was investigated by thermogravimetrical method in the temperature range 1173-1373 K. It was determined that the cermet had the high resistance to oxidation in air in the mentioned temperatures range. Linear, parabolic and logarithm equations were used for the processing of the kinetic curves. The linear dependence of the logarithm of the oxidation rate constant on the value backward to the temperature (1/T) was observed up to the 1273 K. When the temperature increased to 1373 K, the process mechanism changed. The composition of the oxidation products was determined by the X-ray diffraction analysis and scanning electron microscopy method. The double-layer scale formation was found. The internal and external layers differed in the graininess and sizes. The mechanism of oxidation of the cermet in air is proposed, which takes into account the characteristics of oxidation of ceramic and metallic phases, scale morphology and kinetics of its increase.