Abstract
Coating techniques utilizing the collision and adhesion of microparticles on a substrate have recently been attracting attention. However, the bonding between particles deposited on the substrate at room temperature and atmospheric pressure is weak because the kinetic energy of particles during their collision with a substrate is small. The aim of this study is to form ceramic films under these conditions, which is considered difficult. Concretely, the pressurized gas at the surface of the workpiece to be processed is released by the pulsed injection of helium gas using alumina microparticles to form coatings, while preventing the collision speed of the alumina microparticles from decreasing. By pulsed gas injection for 5 min, we succeeded in forming 10-µm-thick alumina ceramic films with a hardness of approximately 40% of that of a sintered alumina body. The results of a friction wear experiment indicated that the coefficient of friction of the films was stable and low (0.15). In addition, the quenched steel balls used in the experiment were worn out, demonstrating that the formed films have good abrasion resistance and adhesion.
