Simulation and Analysis of Temperature Field in NiAl Coatings Prepared by Self-propagating Method

A finite element model with a heat source based on a temperature criterion was used to simulate the combustion synthesis process of the NiAl coating, and the influences of the processing parameters on the distributions of the temperature were analyzed. In addition, the surface and inner temperatures of the reaction system were tested by a thermal infraraed imager and a thermocouple, respectively. The simulated and experimental results of surface temperature distributions of the NiAl compact in the self propagating process are similar, indicating that the finite element model can accurately simulate the temperature changes of the self propagating process. The surface temperature of the substrate reaches the maximum temperature with the propagating of combustion wave. The highest surface temperature at different locations of the matrix are different, distributed wavily, lying at 913.4-1 044.0 degrees C. The temperature of the Ni/Al compact and the substrate can be increased by a preheating. When preheating to 300 degrees C, the surface temperature of the substrate can reach 1 123.3 degrees C. When the Ni/Al reaction was ignited from the middle, the spead rate was the same as that ignited from the side, but the spead time was reduced by half, which caused the combustion more concentrated and the temperature of the compact and substrate higher.