Kinetics of tungsten carbidization under non-isothermal conditions

Kinetic laws of high-temperature interaction between tungsten and methane are studied under non-isothermal conditions in the temperature interval 1273–2873 K. Computer Assisted Electrothermography was applied during which thin metallic wires 100 μm in diameter were directly heated up by electric current in the carbon-containing atmosphere. Experimental data on weight gain, carbide layer growth, and microstructure of phases are obtained in the linear heating regime at heating rates from 10 to 1500 K/s. We established that the interaction between tungsten and methane in a wide interval of pressure and heating rates may proceed with simultaneous or consecutive formation of W2C and WC carbide phases. Experimental data on weight gain and carbide layer growth were processed using calculation schemes deduced within the framework of a reaction diffusion model with the first type boundary conditions under non-isothermal conditions. Kinetic and diffusion constants are determined for tungsten carbidization with formation of the W2C phase.