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Nb 첨가 Zr 합금의 미세조직과 Creep 특성에 미치는 마지막 열처리 온도의 영향
박용권,윤영권,위명용,김택수,정용환,Park, Yong-Gwon,Yun, Yeong-Gwon,Wi, Myeong-Yong,Kim, Taek-Su,Jeong, Yong-Hwan 한국재료학회 2001 한국재료학회지 Vol.11 No.10
The effects of final annealing temperature on the microstructure and creep characteristics were investigated for the Zr-lNb-0.2X (X=0, Mo, Cu) and Zr-lNb- 1Sn-0.3Fe-0.1X (X=0, Mo, Cu) alloys. The microstructures were observed by using TEM/EDS, and grain size and distributions of precipitates were analyzed using a image analyzer. The creep test was performed at $400^{\circ}C$ under applied stress of 150 MPa for 10 days. The $\beta$-Zr was observed at annealing temperature above $600^{\circ}C$. In the temperature above$ 600^{\circ}C$, the grain sizes of both alloy systems appeared to be increased with increasing the final annealing temperature. The creep strengths of Zr-1Nb-1Sn-0.3Fe-0.1X alloys were higher than those of Zr-1Nb-0.2X ones due to the effect of solid solution hardening by Sn in Zr-lNb-lSn-0.3Fe-0.1X alloy system. Also, Mo addition showed the strong effect of precipitate hardening in both alloy systems. The creep strength rapidly decreased with increasing the annealing temperature up to $600^{\circ}C$. However, a superior creep resistance was obtained in the sample that annealed to have a second phase of $\beta$-Zr. It was considered that the appearance of $\beta$-Zr would play an important role in the strengthening mechanism of creep deformation.
Ti-6Al-4V 합금의 미세조직 및 기계적 특성에 미치는 Plasma 침탄 처리의 영향
박용권,김택수,지태구,위명용,Park, Yong-Gwon,Kim, Taek-Su,Ji, Tae-Gu,Wey, Myeong-Yong 한국재료학회 2002 한국재료학회지 Vol.12 No.5
In order to improve the low wear resistance of Ti-6Al-4V alloy, plasma carburization treatment was newly carried out without consumption of its good specific strength and fatigue life over the temperature. Effect of the plasma carburization was analyzed and compared with the non-treated alloy by microstructural observation, structure characterization and mechanical property test. The plasma treated alloy formed a carburized layer of about 150$\mu\textrm{m}$ in depth from the surface, where a fine and hard particles of TiC and $V_4C_3$ were homogeneously dispersed through the layer. It was also found that an increase of the wear resistance, fatigue life and hardness, due to the hard and fine dispersoids.
CrN 박막처리된 Ti-6Al-4V 합금의 기계적 성질과 피로특성
박용권,백창현,위명용,Park, Yong-Gwon,Baeg, Chang-Hyung,Wey, Myeong-Yong 한국재료학회 2002 한국재료학회지 Vol.12 No.8
CrN film coated by AIP method, improved the mechanical properties (Hardness, Roughness, wear and fatigue) of Ti-6Al-4V alloy. The properties were studied using GXRD, XPS, Hardness, Roughness, wear and fatigue testers. CrN thin film thickness was about 7.5$\mu\textrm{m}$ and grew with (111) orientation. Hardness of CrN thin film was very high (Hv 1390) and roughness of the surface layer was greatly improved (Ra=0.063$\mu\textrm{m}$) compared with matrix alloy (Ra=0.321$\mu\textrm{m}$). Such changes of hardness and roughness could be contributed to improving the wear resistance and fatigue life. Striation like pattern with dimples and voids, a typical fatigue fracture mode, was observed throughout the specimen.
박용권(Yong Gwon Park),최재하(Jae Ha Choi) 한국열처리공학회 2001 熱處理工學會誌 Vol.14 No.3
N/A TiO₂thin film has wide application because of its high capacitance, reflection, and good transimissivity in visible range. TiO₂thin film can be made by thermal deposition method, reactive evaporation method, activated reactive evaporation(ARE) method. In the case of thermal deposition, the oxygen deficiency can occur because the melting point of Ti is very high. While in the case of reactive evaporation, high density TiO₂can not be made, because reactive gas(O₂) and evaporated material(Ti) are not fully combined, activated reactive evaporation, TiO₂is easily deposited at lower gas pressure compared with reactive evaporation because the ionized reactive gas is made by plasma. Therefore, activated reactive evaporation is very useful to deposit the material having the high melting point. In this work, we formed TiO₂thin film by activated reactive evaporation method. The surface of TiO₂thin film was analyzed by X-ray photoelectron spectroscopy. The surface morphology which was analyzed by atomic force microscopy(AFM) shows that feature of the film surface is uniform. The dielectric capacitance, withstanding voltage were 600㎌/㎠, 0.4V respectively. In further work, we can increase the withstanding voltage by improving the deposition parameter of substrates.
박용권(Yong Gwon Park),최재하(Jae Ha Choi),위명용(Myeong Yong Wey) 한국열처리공학회 2002 熱處理工學會誌 Vol.15 No.4
N/A The steady-static creep behaviors of Ti-6Al-4V alloy, using the constant stress creep tester, were investigated over the temperature range of 510∼550℃(0.42-0.44Tm) and the stress range of 200-275 MPa(20.41∼28.06 ㎏/㎟). The stress exponents(n) for the static creep deformation of this alloy were 9.85, 9.35, 9.24 and 8.85 at the temperature of 510, 525, 535 and 550℃, respectively. The stress exponent(n) decreased with increasing the temperature and became close to about 5. The apparent activation energies(Q) for the static creep deformation were 254.4, 241.8, 234.4 and 221.9 kJ/mole for the stress of 200, 225, 250 and 275MPa, respectively. The activation energy(Q) decreased with increasing the stress. From the above results, it can be concluded that the static creep deformation for Ti-6Al-4V alloy was controlled by the dislocation climb over the ranges of the experimental conditions. Larson-Miller Parameter(P) for the crept specimens of Ti-6Al-4V alloy under the static creep conditions was obtained as P=(T+460) (log t_T+21). The failure plane observed by SEM showed up dimple phenomenon at all range.
Ti-6Al-4V 합금의 미세조직 및 크리프 특성에 미치는 플라즈마 침탄 처리의 영향
박용권 ( Park Yong Gwon ),위명용 ( Wi Myeong Yong ),박정웅 ( Park Jeong Ung ) 한국열처리공학회 2004 熱處理工學會誌 Vol.17 No.2
N/A In order to improve the wear resistance of Ti-6AI-4V alloy, plasma carburization treatment was newly carried out without consumption of its good specific strength and fatigue life over the temperature. Effect of the plasma carburization was analyzed and compared with the non-treated alloy by microstructural observation, structure characterization and mechanical test. The plasma treated alloy formed a carburized layer of about 150 ㎛ in depth from the surface, where a fine and hard particles of TiC and V₄C₃ were homogeneously dispersed through the layer. The steady-static creep behaviors of Ti-6AI-4V alloy, using the constant stress creep tester, were investigated over the temperature range of 510∼550 ℃(0.42-0.44Tm) and the stress range of 200-275 MPa. Stress exponent(n) was decreased from 9.32 of non-treatment specimen to 8.95 of carburized, however, the activation energy(Q) increased from 238 to 250 kJ/㏖ with the same condition as indicated above. From the above results, it can be concluded that the static creep deformation for Ti-6AI-4V alloy was controlled by the dislocation climb over the ranges of the experimental conditions.