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MoO<sub>3</sub>가 첨가된 Cr<sub>2</sub>O<sub>3</sub>플라즈마 용사코팅의 상온 마찰 마멸 특성
여인웅,안효석,임대순 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.1
플라즈마 용사코팅법을 이용하여 산화몰리브덴이 첨가된 크로미아 용사코팅층을 제조하여 MoO$_3$첨가에 따른 마찰, 마멸특성을 조사하였다. 상온 마찰, 마멸특성에 대한 실험을 위하여 왕복동 마멸시험장치를 사용하였다. 마멸시험후 마멸면의 물리적 변화와 화학적 조성의 변화를 SEM와 XPS를 통하여 살펴보았다. 산화몰리브덴이 첨가된 코팅층에서 마찰계수의 감소를 관찰할 수 있었다. 그러나 마멸량의 경우 산화몰리브덴이 첨가되지않은 크로미아 코팅층에서 가장 낮은 값을 나타내었다. 산화몰리브덴이 첨가된 코팅의 마멸된 표면에 마탈, 마멸에 유리한 보호막의 형성이 광범위하게 일어남을 알 수 있었다. 이러한 보호막에 산화몰리브덴이 MoO$_3$의 형태로 존재하는 것을 XPS분석을 통하여 알 수 있었다. 보호막에 산화몰리브덴의 존재가 마찰계수를 감소시키는 것으로 생각된다. Plasma-sprayed Cr$_2$O$_3$-based coatings containing MoO$_3$were studied to gain a better understanding of the influence of MoO$_3$composition in the coatings on their tribological behaviour. A reciprocal type tribo-tester was employed to examine friction and wear behavior of the specimens at room temperature. The physical characteristics of worn surfaces were investigated by scanning electron microscopy and chemical composition of the coating surfaces was analyzed using a X-ray photoelectron spectrometer. The results showed that friction coefficient of the MoO$_3$-added coatings were lower than those without MoO$_3$addition. However pure Cr$_2$O$_3$coating showed the lowest wear loss at the self-mated test. The larger protecting layers were observed at the worn surface of plasma spray coated specimens with MoO$_3$addition. XPS analysis of the protecting layer indicated that MoO$_3$composition was dominantly formed at the surface. MoO$_3$composition in the protecting layer appears to be more favorable in reducing the friction.
플라즈마 용사법에 의한 Hydroxyapatite 코팅의 용사조건에 관한 연구
여인웅,안효석 한국세라믹학회 1999 한국세라믹학회지 Vol.36 No.4
Hydroxyapatite(HA) was spray-coated to alloy substrate(Ti-6Al-4V) using plasma-spray process for bioceramic application The coating morphology composition and crystallinity were influenced by following process parameters ; stand-off distance spray power level and auxiliary gas pressure. These parameters have been systematically varied in the present study to evaluate their relative influence on the coating qual-ity and to seek an optimum spraying condition. Amorphicity and decomposition of HA increased with stand-off distance and the imperfect coating layer was obtained at the short stant-off distance (55mm). The cry-stallinity of HA coating decreased with spray power level and auxiliary gas pressure but the bond strength between the HA coated layer and Ti alloy substrate increased with the spray power level.
열간가압소결법으로 제조된 Sialon세라믹스의 Erosion특성에 관한 연구
여인웅,임대순,박동수 한국트라이볼로지학회 1997 한국윤활학회지(윤활학회지) Vol.14 No.1
Three kinds of the sialon ceramics with and without TiN additions were prepared by hot pressing to investigate the effect of microstructure on erosion behaviors. Hardness and fracture toughness were measured with prepared specimens to study the effect of additives on the mechanical properties. A gas blast type erosion tester was employed to examine erosion behavior of the specimens up to $600^{\circ}C$. Erosion tests showed an increase of erosion rate up to 40$0^{\circ}C$ and a gradual decrease of erosion rate up to 50$0^{\circ}C$ for all kinds of sialon. The results also showed that erosion rates of the sialons were controlled better by microstructural factors than by mechanical properties including fracture toughness and hardness.
MoO3가 첨가된 Cr2O3 플라즈마 용사코팅의 고온 마찰 마멸 특성
여인웅,안효석,임대순 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.9
Tribological behavior of plasma-sprayed Cr2O3-based coatings containing MoO3 at 450oC was investigated to understand the influence of MoO3. A reciprocal disc-on-plate type tribo-tester was employed to examine friction and wear behavior of the specimens. The microstructure and phase composition of the coating was characterized with transmission electron microscopy (TEM). The TEM analysis indicated that MoO3 was dispersed into the grain boundary, resulting in the increase of the hardness and density of the coating. Worn surfaces were investigated by scanning electron microscopy and chemistry of the worn surfaces was analyzed using a X-ray photoelectron spectrometer (XPS). The results showed that the friction coefficient of the MoO3-added coatings was lower than that without MoO3 addition. The larger protecting layers were observed at the worn surface of plasma spray coated specimens with MoO3 addition. XPS analysis of the protecting layer indicated that MoO3 composition was dominantly formed at the surface. MoO3 composition in the protecting layer appears to be more favorable in reducing the friction.
MoO<sub>3</sub>가 첨가된 Cr<sub>2</sub>O<sub>3</sub> 플라즈마 용사코팅의 고온 마찰 마멸 특성
여인웅,안효석,임대순,Lyo, In-Woong,Ahn, Hyo-Sok,Lim, Dae-Soon 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.9
산화몰리브덴($MoO_3$)이 첨가된 산화크롬 용사코팅층을 제조하여 산화몰리브덴의 첨가에 따른 고온(450$^{\circ}C$)에서의 플라즈마 용사코팅층에 마찰, 마멸특성을 조사하였다. 마찰, 마멸 특성에 대한 실험을 위하여 왕복동 마멸시험장치를 사용하였다. TEM을 이용하여 코팅층의 미세 구조와 각 상들의 조성을 살펴보았다. 분석 결과에 의하면 산화몰리브덴이 입계로 분산되어 있어 코팅층의 경도와 밀도의 증가가 발생하였다. 마멸시험후 마멸면의 물리적 변화와 화학적 조성의 변화를 SEM와 XPS를 통하여 살펴보았다. 산화몰리브덴이 첨가된 코팅층에서 마찰계수의 감소를 관찰할 수 있었다. 산화몰리브덴이 첨가된 코팅의 마멸된 표면에 마찰, 마멸에 유리한 보호막의 형성이 광범위하게 일어남을 알 수 있었다. 이러한 보호막에 몰리브덴이 산화몰리브덴의 형태로 존재하는 것을 XPS 분석을 통하여 알 수 있었다. 보호막에 산화몰리브덴의 존재가 마찰계수를 감소시키는 것으로 생각된다. Tribological behavior of plasma-sprayed $Cr_2O_3$-based coatings containing $MoO_3$ at 450$^{\circ}C$ was investigated to understand the influence of $MoO_3$. A reciprocal disc-on-plate type tribo-tester was employed to examine fricition and wear behavior of the specimens. The microstructure and phase composition of the coating was characterized with Transmission Electron Microscopy(TEM). The TEM analysis indicated that $MoO_3$ was dispersed into the grain boundary, resulting in the increase of the hardness and density of the coating. Worn surfaces were investigated by scanning electron microscopy and chemistry of the worn surfaces was analyzed using a X-ray Photoelectron Spectrometer(XPS). The results showed that the friction coefficient of the $MoO_3$-added coatings was lower than that without $MoO_3$ addition. The larger protecting layers were observed at the worn surface of plasma spray coated specimens with $MoO_3$ composition in the protecting layer appears to be more favorable in reducing the friction.