Effect of partial crystallization of an amorphous layer on the mechanical properties of ceramic/metal-glass coating by thermal spraying

On the basis of successful preparation of amorphous-ceramic composite coating by atmospheric plasma spraying, a nanostructure bond-coat was prepared in-situ by inducing partial crystallization of an amorphous layer through heat treatment. The unit mechanics contribution rate (UMCR) was proposed to evaluate the mechanical properties of the coating, and the interference of the substrate to the evaluation of the coating mechanical properties was removed. In this work, the mechanical properties of the coating were systematically evaluated at the macroscopic, mesoscopic and microscopic scales through three-point bending (3 PB), microhardness and nanoindentation tests, respectively. Results show that the nanoparticle-ceramic coatings formed by heat treatment have a higher hardness and Young's modulus. The mechanical properties at the micro scale were obviously better than those at the macro scale. A partial crystallization was observed in the amorphous bond-coats in the process of heat treatment, and a large number of nanoparticles and solid solution were formed in the nanoparticle-ceramic coatings, effectively hindering the crack growth and improving the coating performance.