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RISS 인기검색어
- 검색키워드
- 저자 : 서용찬(Suh Yong Chan) (검색결과 3 건)
- 무료
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김영석(Kim Young Suk),서용찬(Suh Yong Chan),안상복(Sang Bok Ahn),정용무(Cheong Yong Moo),임경수(Im Kyung Soo) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.3
With a view to assessing a change in the creep rate of the Zr-2.5Nb pressure tubes operating in the reactor with the operation time, Zr-2.5Nb sheets were made with four different kinds of manufacturing process to simulate a microstructural change of the pressure tubes with time. The creep tests were conducted on the Zr-2.5Nb sheets at temperatures ranging from 623 to 673 K and constant stress of 120 ㎫. As an indirect evaluation of the Nb content dissolved in the α-Zr grains, the Nb content in the β-Zr phase of Zr-2.5Nb sheets made with 4 different processes was measured using a replica method. Zr-2.5Nb made with process P1 had the lowest creep rate while that made with process P3 or P4 had the highest creep rate. By correlating the Nb content in the α-Zr grains with the creep rate and strength of the Zr-2.5Nb sheets, we conclude that the Nb contents dissolved in the the c-Zr grains governs the creep rate and strength of Zr-2.5Nb alloy. A change in the creep rate of the Zr-2.5Nb pressure tubes was discussed on the basis of a fact that α-Zr grains in the Zr-2.5Nb pressure tubes have the Nb content decreasing with the operation time increasing.
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이진형,서용찬,조대식 대한금속재료학회(대한금속학회) 1993 대한금속·재료학회지 Vol.31 No.7
In RS aluminum alloy powders, the surface oxide formed on powders usually contains significant amounts of physically adsorbed water and oxygen. Hence, it is necessary to remove both the adsorbed gas and water from the surface of the powders before consolidation, in order to achieve full density. This removal is usually accomplished by a degassing step. A study has been perfomed on the effectiveness of degassing processes of AC8A alloy powders. Mathematical analysis on the degassing time in the degassing process was done and the factors determining the degassing time were investigated. Computer simulation for degassing process in the powder compact was done considering evaporation, diffusion and reaction. According to the results of simulation, degassing time decreases with decreasing size of powder compact and increasing pore radius. Based on the above results, two method of degassing was performed and compared: static degassing process and dynamic degassing process. The mechanical properties of the specimen made from the dynamic degassing method was superior and its degassing time was much shorter than the other method.
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치과 주조용 Ag-Pd 계 합금의 미세조직에 미치는 S 와 Ir 의 영향
이진형,서용찬,신승렬 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.1
The effects of S and Ir on the microstructures of binary Ag-25%Pd alloy and a commercial alloy, A-2 (Ag-25 wt%Pd-2 wt%Au-2 wt%In-0.84 wt%Zn-0.5 wt%Ir) were studied. The segregation tendency of S in the grain boundary was investigated by Auger electron spectroscopy (AES) and Energy Dispersive Spectroscopy (EDS) with varying S concentrations. The effect of the cooling rate on the microstructures and segregation was also investigated. The compositions of several positions on the fractured surface were measured by EDS analysis. The grain refining effect of Ir was obvious when the concentration of Ir was more than 0.1%. At S-concentrations above 0.1%, Ag₂Pd₃S phase was observed at the dendrite and grain boundary due to S-segregation during solidification. This phase did not appear at 0.01% S, but the S-concentration at the grain boundary was much higher than the bulk concentration, showing S-segregation to the grain boundary. The degree of S-segregation to the grain boundary decreased slightly with grain refining. The segregation of In and Zn in A-2 alloy containing high S concentration did not occur while it occurred in the alloy with low S concentration.
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