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혼합조건에 따른 철분말 소결체의 특성 변화에 관한 연구
김한삼 ( Han-sam Kim ),최태규 ( Tae-kyu Choi ),박종성 ( Chong-sung Park ) 한국고등직업교육학회 2002 한국고등직업교육학회논문집 Vol.3 No.4
The microstructure and mechanical characteristics of sintered materials composed oi Fe-xwt.%P with mixing times had been studied. The Fe+xwt.%P(x = 0.25, 0.5, 0.75,1) powders were sintered for 2 hours at 940°C. Before sintering of the powders, each of powder composition was worked into ball-mill machine for 12, 24, and 48 hours. The shrinkage of preform increased with phosphorus amount and mixing time during sintering. Pores and Fe<sub>3</sub>P facet type phase in the grain boundary and grain of sintered materials were observed by means of scanning electron microscope. Amounts of pores and the size of Fe<sub>3</sub>P phase decreased with increase of the mixing time. The hardness of sintered materials depended upon the content of phosphorus and the mixing time of powder. The hardness increased with the increase of phosphorus content and mixing times.
플라즈마 용사 Wc-12%Co 피복층의 탄화처리에 관한 연구
김수식,김한삼,이홍주 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.5
Tungsten Carbide(WC) coatings were formed on mild steel substrates using the plasma spray process. As a mean to enhance the mechanical properties such as microhardness and wear resistance, as-sprayed coatings were annealed and then subsequently were subjected to the carburization under methane and hydrogen atmospheres. When the heat treatment was carried out under the hydrogen atmosphere, the amounts of WC phase were decreased and the amounts of α-W₂C and W phase were increased with the increase of temperature, which leaded to a slight reduction of the microhardness. In case of the carburization under methane atmosphere, the microhardness of the coatings was increased with the increase of temperature and show the highest value of 1540Hv at 1100℃. The wear resistance also was increased with the increase of the carburization temperature. The wear resistance of the coatings heat treated at 1100℃ were 17 times higher than the as-sprayed coatings. The increase of methane concentration at constant temperature at 900℃ showed the improvement of the microhardness and the wear resistance of coatings. The highest microhardness and wear resistance obtained at the methane concentration of 11%.