Effects of microstructure and properties on parameter optimization of boron carbide coatings prepared using a vacuum plasma-spraying process

This study employed artificial intelligence methods such as the Taguchi Method to determine the optimal parameters for boron carbide (B4C) coatings using a vacuum plasma spray technique. We determined the optimal parameters to produce coatings and investigated B4C coatings in an electromagnetic radiation environment by observing and analyzing changes in the microstructure and properties. These artificial intelligence methods comprised two stages. In the first stage, orthogonal arrays (OA) were used to distribute test parameters, and the Taguchi Method was used to optimize the parameters. In the second stage, a specimen of boron carbide coating was evenly exposed to radiation to investigate the microstructure and properties of the coating. The coating irradiated at a wavelength of 10.6 μm did not undergo any change in phase. The microstructure of the surface coating exhibited cracks, but these were insignificant. As the irradiation time increased, the number of cracks on the surface increased significantly. In addition, because the growth of surface cracks was governed by irradiation time, it was inferred that the growth was thermal efficiency-controlled (i.e., only generated by heating effects). Additionally, under irradiation, the surface of the boron carbide coating became oxidized and formed B2O3, H3BO3, and amorphous carbon; the coating size increased proportionally with irradiation time and weight of oxidation. The initial oxidation of the coating was classified as surface controlled, and the oxidation that formed on the B2O3 surface gradually transformed into extended controlled oxidation. Both types of oxidation control were conducted simultaneously, causing the weight of B2O3 to increase linearly. Two processes were involved in the extended control of oxidation: the formation of B2O3 (the cause of weight gain), and the vaporization of B2O3 (the cause of weight loss).