플라즈마/레이저 복합용사에 의한 $ZrO_2-8%Y_2O_3$ 코팅층의 미세구조 및 기계적 특성

Microstructures and Mechanical Properties of $ZrO_2-8%Y_2O_3$ Coating Layer by Plasma/Laser Complex Spraying

This study was aimed at observing the influence of laser irradiation on a $ZrO_2-8%Y_2O_3$ ceramic coating layer fabricated by plasma spraying. The $ZrO_2-8%Y_2O_3$ ceramic powder was plasma sprayed onto SS400 carbon steel substrate and laser irradiated on the coating layer under various conditions of laser power and beam diameters. As to the as-sprayed specimen and laser-treated specimen, a hardness test and a microstructure analysis were performed. Hardness was measured by a microhardness tester; microstructure was observed by an optical microscope and a scanning electron microscope. The result was that the microstructure of the laser-irradiated coating layer was dense; porosities almost disappeared and hardness increased. It was also observed that microcracks occured in the laser-irradiated coating layer.