WC-Co 초고속 화염용사코팅 표면특성에 미치는 분말입자의 크기

The effects of particle size on the surface properties of HVOF spray coating were studied to improve of the durability of metal components. Micro and nano sized WC-12Co powders were coated on the surface of Inconel718, and the effects of particle size on surface properties were studied. Surface hardness was reduced when the particle sizes of the powder were decreased, because the larger specific surface area of the smaller particles caused greater heat absorption and decomposition of the hard WC to less hard W2C and graphite. Porosity was increased by decreasing the particle size, because the larger specific surface area of the smaller particles caused a greater decomposition of WC to W2C and free carbon. The free carbon formed carbon oxide gases which created the porous surface. The friction coefficient was reduced by decreasing the particle size because the larger specific surface area of the smaller particles produced more free carbon free Co and Co oxide which acted as solid lubricants. The friction coefficient increased when the surface temperature was increased from 25 to 500 ℃, due to local cold welding. To improve the durability of metal mechanical components, WC-Co coating with the proper particle size is recommended. (Received August 22, 2016; Accepted October 28, 2016)