The effect of vacuum heat treatment in the thermal sprayed ceramics coating on a capstan by either high velocity oxygen fuel(HVOF) or plasma thermal spray process was investigated. The coating materials applied on the capstan were tungsten and chrome ...
The effect of vacuum heat treatment in the thermal sprayed ceramics coating on a capstan by either high velocity oxygen fuel(HVOF) or plasma thermal spray process was investigated. The coating materials applied on the capstan were tungsten and chrome carbides. In order to characterize the interface between coating layer and bare materials, hardness, adhesion strength, X-ray diffraction(XRD) and microstructural analysis are conducted. The adhesion strength of the carbide coated materials by HVOF process is over 500㎫ compared to those of plasma coating process is 230㎫. In case of the carbide coated materials by HVOF process, the adhesion strength is increased to 15㎫ and the porosity is reduced under 5% by vacuum heat treatment for 5 hrs at 1000℃. The XRD results reveal that the increasement is believed due to the phase stabilization of metastable Cr₃C₂phase to stable Cr_(23)C_6 phase.