HVOF 용사에 의한 WC-CoCr 코팅 최적화를 위한 다구치 실험계획방법의 적용

Cermet coating by thermal spraying has been a feasible application for the wear resistant coating on the various machine components. Tungsten carbide-based coatings are generally used for the abrasive, sliding, and erosive wear resistance of turbine engine part applications. Carbide coatings are predominantly deposited by high velocity oxy-fuel (HVOF) process in order to avoid the decarburization of the carbides during thermal spraying. Although the HVOF process has much lower temperature and less in-flight time compared with plasma spraying process, decarburization of WC occurs during the HVOF spraying and it causes degradation of wear properties. In this study, in order to minimize the decarburization of WC for WC-10Co-4Cr coatings, HVOF process parameters were optimized using Taguchi`s method for design and analysis of experiment. HVOF process parameters for optimization were the flow rates of gases (oxygen and fuel), powder feeding rate and spraying distance. Decarburization of WC was estimated by comparing the relative height of the main peaks of W2C and WC (I(W2C)/I(WC)). After optimization, decarburization of WC was diminished without considerable deterioration of microstructure.