Abstract
Thermal sprayed WC-metal binder cermet coating is widely used for their resistance to abrasive wear in various harsh environments and generally sprayed by high velocity oxy-fuel (HVOF) method and atmospheric plasma spray method (APS). However, even during HVOF spraying, WC-metal binder cermet powder has to be exposed to high temperature flame jet for heating and accelerating, furthermore, oxygen is usually entrained into the flame jet, the decomposition and decarburization of tungsten carbide owing to the oxidation of WC, cannot be totally eliminated. This frequently causes defects such as pores, cracks and unmelted particles, which deteriorate coatings properties. To improve the properties of sprayed coatings, numerous studies have been examined post treatments such as laser irradiation, diffusion treatment, hot isostatic pressing (HIP) treatment, sealing treatment. Laser irradiation was speedy treatment and simplicity of process control and enables not only the post treatment but also the pre and simultaneous treatment by combining with spraying process. However, it is not easy to produce a uniformly treated coating by conventional laser treatment method as desired. To obtain a near-uniform beam intensity for practical laser irradiation, a kaleidoscope was installed in a conventional YAG laser. In this work, laser beam properties of YAG laser equipped with a kaleidoscope and its effect on surface modification of WC-25%NiCr coating was investigated. Abstract only; no full-text paper available.
