SIMULATION OF THE PROCESS OF CHROMIZING AND SILICONIZING UNDER THE CONDITIONS OF SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS

Abstract

Coatings deposited under the conditions of self-propagating high-temperature synthesis (SHS processes) accompanied by vapor-transport reactions have many peculiar properties. They consist of a film of the deposited product (as a result of vapor-phase precipitation) and a wide transition diffusion (gradient) zone (produced by diffusion saturation) [1]. The method for depositing vapor-transport SHS coatings has been suggested by E. A. Shtessel’ and E. P. Kostogorov [2] and studied in detail by the authors of [3 – 7]. The method is based on the occurrence of exothermic reactions in a mode of propagating combustion waves. In contrast to the known diffusion methods of chromizing and siliconizing [8] that are energy-intensive and long lasting, the SHS method can provide diffusion layers in a mode of combustion or thermal ignition in a short time (from several minutes to 1 – 2 h). The formed layer is from several microns to 1 – 2 mm thick. The thickness of the protective layer may be controlled by the time parameters of the process and the thermophysical characteristics of the SHS mixtures. In the present work we modeled the processes of chromizing and siliconizing under the conditions of SHS.