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RF Plasma 법으로 증착된 TiCN 박막의 구조 및 기계적 거동에 관한 연구
위명용,백창현,박상렬,홍주화,강희재 한국열처리공학회 2000 熱處理工學會誌 Vol.13 No.2
The structure and mechanical properties of TiN and TiCN thin films deposited on STD61 steel substrates by the RF-sputtering methods has been studied by using XPS, XRD, micro-hardness tester, scratch tester, and wear-resistance tester. XPS results showed that the TiCN thin film formed with chemical bonding state. The TiN thin films grew with (111) orientation having the lowest strain energy by compressive stress, whereas the TiCN thin films grew with both (111) and (200) orientation, but (200) orientation having the lowest surface energy becomes dominant as carbon contents increase. The pre-etching treatment of substrate did not affect on the preferred orientation of thin films, but it played an important role in improving mechanical properties of thin films such as the hardness, adhesion and wear-resistance. Especially, the TiCN thin films showed the superior wear resistances due to high hardness and low friction coefficient compared with TiN thin films.
위명용,백창현,홍주화,강희재 한국열처리공학회 2000 熱處理工學會誌 Vol.13 No.5
Microstructure, mechanical and fatigue behaviors of TiCN and TiN/TiCN thin films, deposited on quenched and tempered STD61 tool steel, were investigated by using XRD, XPS, hardness, adhesion and fatigue tests. The TiCN thin film is grown along the (100), (111) orientation, whereas the TiN/TiCN thin film is grown along the (111) orientation. The preferred orientation of TiN/TiCN thin film strongly depends on the TiN buffer layer whose orientation is (111), as is well-known. The TiN/TiCN thin film showed the higher adhesion compared with TiCN single layer because the TiN buffer layer, having good toughness, reduces the effects of the lower hardness of substrate. In the high cycle tension-tension fatigue test, the fatigue life of the TiCN and the TiN/TiCN coated steel increased approximately two to four times and five to nine times respectively compared with uncoated specimens. The TiN buffer layer in multilayer thin films plays an important role in reducing residual stress and fatigue crack initiation, and then in restraining the fatigue propagation.
위명용 한국열처리공학회 1998 熱處理工學會誌 Vol.11 No.4
The grain growth characteristics of dual-phase (α+γ) containing high Cr-steel have investigate using α-, γ-single phases and (α+γ) dual-phase of 12%Cr Steel. The heat treatment has performed at 1000-1200℃ for 1-100hr. The results are as follows : 1) The grain growth rate in (α+γ) dual phase was substantially slower than that of single grain. 2) The relation between mean grain radius γ ̄ and annealing time t is, in general described as following equation : (r ̄)^n-( (r_o) ̄ )^n=k_n·t……(1) i) In the case of single phase of high Cr steel, Eq.(1) is described as (r ̄)²-((r_o) ̄)²=k₂·t and the grain growth is controlled by boundary migration. ii) In dual phase, the grain growth needs diffusion of alloying elements because the chemical composition of α- and γ- phases differs from each other. When the volume fraction of α- , γ-phase was almost equal and γ-phase in the case of 80 and 90%γ. Eq. (1) is described as (r ̄)³-((r_o) ̄)³=k₃·t because the grain growth is controlled by volume diffusion iii) In the case of γ-rich phase (80 and 90%γ), the grain growth of minor phase (10 and 20%α) is described as (r ̄)⁴-((r_o) ̄)=k₄·t because the boundary diffusion is predominent rather than volume diffusion.
위명용,박익흥 충북대학교 건설기술연구소 1993 建設技術論文集 Vol.12 No.2
Microstructure, hardness, tensile strength and wear characteristics of gray cast iron with pearlite matrix, in the range of phospor concentration from 0.1∼0.96 wt%, were examined. The results were as follows : 1) As the content of phospor increases, the amount of steadite and hardness increase. 2) As the content of phospor increases, the tensile strength increases up to 0.3wt%P but gradually decreases beyond that point. 3) As more phospor is added, wear amount decreases and as content load increases, wear amount increases. In high load state, effective wear resistence can be obtained at around 0.8wt% and in medium and low load state, 0.3wt%P is the optimal level 4) As the hardness of rotor increase, wear amount increases. Wear amount decreases acutely up to 0.3wt%P but, beyond that point, it decreases slow down. Therefore effective wear resistance ran be obtained at around 0.3wt%P.
복합처리 (Carburized/CrN Coating)로 표면개질된 Ti-6Al-4V 합금의 구조 및 피로특성
위명용,박용권 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.12
In order to improve the surface hardness and fatigue of Ti-6A1-4V alloy, plasma carburization and CrN coating were carried out. After composite surface treatment, the depth of carburized layer was about 150 μm and the thickness of CrN coated layer was about 7.5 pm, respectively. Surface hardness and roughness was significantly improved up to about H_(v)1,960 and 0.045 pm after plasma carburized/CrN coating in comparison with the value hardness and roughness, H_(v), 402 and 0.321 μm of the alloy before surface modification. This result might be associated with the formation of TiC carburized layer and CrN coating on the surface of Ti-6A1-4V alloy. During the scratch test of coating, critical load was as high as 32N as compared with the simply processed CrN coating of a 18N. Such changes of hardness and roughness could be contributed to improving the fatigue life. (Received July 14, 2004)
위명용,장곡부 광홍 ( Wey Myeong Yong,Hasebe Mitsuhiro ) 한국열처리공학회 1997 熱處理工學會誌 Vol.10 No.2
In order to elucidate thermal stability of Fe-Fe₂Ti eutectic structure, the initial several structures have been investigated in the changes of coarsening and spheroidization during prolonged annealing under the eutectic temperature. The results are as follows: 1) The rate constant of coarsening and spheroidization was formulated as S^(-n)-S^(-n)_0=k·t, where S is the total area of the interface between α and C(Fe₂Ti) per unit volume, S_0 is initial value and k is the rate constant. 2) The coarsening and spheroidization mechanism was described by Ostwald ripening and controlled by diffusion of Ti-atom in α-phase. 3) The spheroidization rate constant in eutectic lamellar structures was depended upon annealing temperature and showed the Arrhenius relation. The activation energy for spheroidization of lamellar structure was 365 kJ/mole.