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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.
이준섭(J. S. Lee),조동율(T. Y. Cho),윤재홍(J. H. Yoon),주윤곤(Y. G. Joo),송기오(K. O. Song),조재영(J. Y. Cho),강진호(J. H. Kang),이선호(S. H. Lee),엄기원(K. W. Uhm),이종욱(J. W. Lee) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.1
Recently ultra-supercritical steam power plants operate at 1000℉ (538℃) and 3500 psi (24.1 ㎫). Thermal efficiency of power plant will be increased about 2% if steam temperature increases from 1000℉ to 1150℉ (621℃). In this study valve materials Incoloy901 (IC901) and Inconel718 (IN718) were nitrided to improve the surface hardness and solid lubrication function of the valve materials. The hardness of both IC901 and IN718 increased about two times by ion nitriding. IC901, IN718 and their nitrided specimens were corroded under ultra super-critical condition (USC) of 621℃. and 3600 psi (24.8 ㎫) for 2000 hours. Oxidations of both IC901 and IN718 were very small due to the formation of protective oxide layer on the surface. But the corrosion resistance of both nitrided specimens decreased because of the formation of non-protective nitride layer of Fe₄N, Fe₂N and CrN on the surface layer. The hardness of both nitrided IC901 and IN718 at 20 ㎛ depth from the surface decreased about 30% and 20% respectively by USC 2000 hours.
Incoloy 909 합금의 최적 알루미나이징 확산 코팅
권순우(S.W. Kwon),윤재홍(J.H. Yoon),주윤곤(Y.K. Joo),조동율(T.Y. Cho),안진성(J.S. Ahn),박봉규(B.K. Park) 한국표면공학회 2007 한국표면공학회지 Vol.40 No.4
An Fe-Ni-Co based superalloy Incoloy 909 (Incoloy 909) has been used for gas turbine engine component material. This alloy is susceptible to high temperature oxidation and corrosion because of the absence of corrosion resistant Cr. For the improvement of durability of the component of Incoloy 909 aluminizing-chromate coating by pack cementation process has been investigated at relatively low temperature of about 550℃ to protect the surface microstructure and properties of lncoloy 909 substrate. As a previous study to aluminizing-chromate coating by pack cementation of Incoloy 909, the optimal aluminizing process has been investigated. The size effects of source AI powder and inert filler Al₂O₃ powder and activator selection have been studied. And the dependence of coating growth rate on aluminizing temperature and time has also been studied. The optimal aluminizing process for the coating growth rate is that the mixing ratio of source Al powder, activator NH₄Cl and filler Al₂O₃ are 80%, 1% and 19% respectively at aluminizing temperature 552℃ and time 20 hours.