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초고속 스핀들의 내구성 향상을 위한 WC-Co 분말의 HVOF 용사 코팅
김길수(K.S. Kim),백남기(N.K. Baek),윤재홍(J.H. Yoon),조동율(T.Y. Cho),윤석조(S.J. Youn),오상균(S.K. Oh),황순영(S.Y. Hwang),천희곤(H.G. Chun) 한국표면공학회 2006 한국표면공학회지 Vol.39 No.4
High velocity oxygen fuel(HVOF) thermal spray coating of WC-Co powder is one of the most promising candidate for the replacement of the traditional hard chrome plating and ceramics coating because of the environmental problem of the very toxic Cr6+ known as carcinogen and the brittleness of ceramics coating. WC-Co micron and nano powder were coated by HVOF thermal spraying method for the study of durability improvement of the high speed spindle. Coatings were planned by Taguchi program for the four spray parameters of spray distance, flow rates of hydrogen, oxygen and powder feed rate. Optimal coating process was obtained by the studies of coating properties such as porosity, surface roughness, micro hardness, and microstructure. WC-Co micron and nano powder were coated on the Inconel 718 substrate by the optimal coating process obtained in this study. The wear behaviors were studied by the sliding wear tester at room temperature and at an elevated temperature of 500°C for the application to high speed spindle. Sliding wear test was carried out for four most promising hard coatings of chrome coating, ceramics coatings such as Al₂O₃, Cr₂O₃ and HVOF Co-alloy T800 for the comparison of their wear behaviors. HVOF WC-Co coating was better than other coatings showing highest micro hardness of 1400 Hv and comparable friction coefficients with others. HVOF WC-Co coating is a strong candidate for the replacement of the traditional hard chrome plating for the high speed spindle.
터보불로워 용 회전체 주축 소재의 마찰,마모 및 부식 저항 향상을 위한 WC- metal 분말의 초고속화염용사코팅
주윤곤 ( Y K Joo ),윤재홍 ( J H Yoon ),조동율 ( T Y Cho ),천희곤 ( H G Chun ) 한국부식방식학회(구 한국부식학회) 2013 Corrosion Science and Technology Vol.12 No.1
High velocity oxy-fuel (1-IVOF) spray coating of WC-metal powder (powder) was carried out to improve the resistances of friction, wear and corrosion of magnetic bearing shall material lnconel7 18 (1n71 8) of turbo blower. A micron sized WC-inetal powder (86.5% WC, 9.5% Co 4% Cr) was coated onto 1n718 surface using HVOF thermal spraying. During the spraying, the binder metals and alloy such as o. Cr and Co-Cr alloy were molten and a small portion of WC particles were partially decomposed to W2C and free carbon at above its decomposition temperature of 1250°C. The free carbon and excessively sprayed oxygen fomied carbon oxide gases. resulting a porous coating of porosity of 2.2±0.3%. The surface hardness of substrate increased approximately three times from 40() H of 1718 to 1260±30 I-h of the coating The friction coefficients of the coating were approximately 0.33 ± 0.03 at 25°C and 0.26 ± 0.03 at 450°C. These values were smaller than those of 1n7 18 substrate at both temperatures due to the lubrication from the free carbon and the cobalt oxide debris. The corrosion resistance of the coating was higher than that of ln718 both in salt water of 3.5% NaCI and acid of I M I-Id solutions, on the contrary, it was lower in base solution of I M NaOH. According to this study. the 1-IVOF WC-metal powder coating is recommended for the durability improvement of magnetic hearing shaft of turbo blower.