In this study, we evaluated the effects of acid leaching on the properties of Cr powder synthesized using self-propagating high-temperature synthesis (SHS). Cr powder was synthesized from a mixture of Cr2O3 and magnesium (Mg) powders using the SHS Process, and the byproducts after the reaction were removed using acid leaching. The properties of the recovered Cr powder were analyzed via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), particle size analysis (PSA), and oxygen content analysis. The results show that perfect selective leaching of Cr is challenging because of various factors such as incomplete reaction, reaction kinetics, the presence of impurities, and incompatibility between the acid and metal mixture. Therefore, this study provides essential information on the properties under acidic conditions during the production of high-quality Cr powder using a self-propagating high-temperature synthesis method.

We report the feasibility of TaC production via self-propagating high temperature synthesis, and the influence of the initial green compact density on the final composite particle size. Experiments are carried out from a minimum pressure of 0.3 MPa, the pressure at which the initial green body becomes self-standing, up to 3 MPa, the point at which no further combustion occurs. The green density of the pellets varies from 29.99% to 42.97%, as compared with the theoretical density. The increase in green density decreases the powder size of TaC, and the smallest particle size is observed with 1.5 MPa, at 10.36 μm. Phase analysis results confirm the presence of the TaC phase only. In the range of 0.3-0.5 MPa, traces of unreacted Ta and C residues are detected. However, results also show the presence of only C residue in the matrix within the pressure range of 0.6-3.0 MPa.

Microstructure, electric, and thermal properties of the Ta-Cu composite is evaluated for the application in electric contact materials. This material has the potential to be used in a medium for a high current range of current conditions, replacing Ag-MO, W, and WC containing materials. The optimized SPS process conditions are a temperature of 900oC for a 5 min holding time under a 30 MPa mechanical pressure. Comparative research is carried out for the calculated and actual values of the thermal and electric properties. The range of actual thermal and electric properties of the Ta-Cu composite are 50~300W/mk and 10~90 %IACS, respectively, according to the compositional change of the 90 to 10 wt% Ta-Cu system. The results related to the electric contact properties, suggest that less than 50 wt% of Ta compositions are possible in applications of electric contact materials.

본 연구는 부존 조사료자원의 이용을 활성화하여 수립사료를 줄이고 가축 사료비를 절감하고자 2010년도에 경기 파주(민통선지역)와 경기 안산(시화지구)에서 갈대와 억새 등 야초자생지를 탐색하고, 수확 이용실태 조사와 함께 사료가치를 분석하였다. 파주 민통선 내억새(Miscanthus sinensis)와 갈대(Phragmites communis)혼합 자생지는 90~100 ha규모로, 1520톤(ha당 6톤), 2차로 380톤(ha당 4톤)을 제조하여, 연