As a basic study for the removal of oxygen in solid Nd metal by metal Ca vapour, by using the thermodynamic data such as ΔG-T diagrams and Nd-O and Nd-Ca equilibrium diagrams, the amount of residual oxygen in solid Nd metal formed based on deoxidation reaction by Ca vapour, instead of by direct contact of solid Nd metal and Ca solution, was determined. Deoxidation experiments were carried out for solid Nd metal in a temperature range of 890~970 ℃ for 1h to 4h and content of addition Ca of 0.6~1.8 g (5~15 wt% of solid Nd metal). As a result, it was found that as deoxidation temperature increased, dissolved oxygen decreased. Especially, it was observed that a small amount of Nd-Ca alloy liquid was formed on the surface of the solid Nd metal sample deoxidized at 970 ℃ for approximately 1 hour. Also, it was found that if the content of addition Ca was 1.8 g (15 wt% of solid Nd metal) the amount of produced Nd-Ca alloy increased slightly. However, for the Nd sample with which the deoxidation reaction was performed at 930 ℃ for 4h with content of addition of Ca of 1.5 g (13 wt% of Nd metal), the residual oxygen was found to decreased to 12.00 ppm.

This study is carried out to obtain basic data regarding oxidation and reduction reactions, originated on the recycling of waste tungsten hard scraps by oxidation and reduction processes. First, it is estimated that the theoretical Gibbs free energy for the formation reaction of WO2 and WO3 are calculated as ΔG1,000K= -407.335 kJ/mol and ΔG1,000K = -585.679 kJ/mol, from the thermodynamics data reported by Ihsan Barin. In the experiments, the oxidation of pure tungsten rod by oxygen is carried out over a temperature range of 700-1,000oC for 1 h, and it is possible to conclude that the oxidation reaction can be represented by a relatively linear relationship. Second, the reduction of WO2 and WO3 powder by hydrogen is also calculated from the same thermodynamics data, and it can be found that it was difficult for the reduction reaction to occur at 1,027oC, in the case of WO2, but it can happen for temperatures higher than 1127oC. On the other hand, WO3 reduction reaction occurs at the relatively low temperature of 827oC. Based on these results, the reduction experiments are carried out at a temperature range of 500-1,000oC for 15 min to 4 h, in the case of WO3 powder, and it is possible to conclude that the reduction at 900oC for 2h is needed for a perfect reduction reaction.

For the purpose of obtaining basic information on the development of lead-free materials, a high density composites (a) W-Cu, (b) W-Sn (c)W-Cu-Sn and (d) W-Cu-Ni were fabricated by the P/M method. The particle size of used metal powders were under 325 mesh, inner size of compaction mould was mm, and compaction pressure was 400 MPa. A High density composite samples were sintered at a temperature between and for 1 hour under Ar atmosphere. The microstructure, phase transformation and physical properties of the sintered samples were investigated. As the results, the highest relative density of 95.86% (10.87 g/) was obtained particularly in the sintered W-Cu-Sn ternary system sample sintered at 450 for 1hr. And, Rockwell hardness (HRB) of 70.0 was obtained in this system.

환원.확산법에 의해 Sm2Fe17Nx 계 희토류 영구자석을 제조하기 위한 기초연구로서, 우선 Sm2Fe17 금속간화합물의 제조를 위하여, 금속 Ca에 의한 Sm2O3의 환원반응과 Fe분말중에 Sm의 확산반응을 검토하였다. 그 결과 전자는 1000˚C이상의 고온의 경우에 매우 빠르게 완료되지만, 후자의 Fe분말의 중심까지 Sm의 확산반응의 완료(완전한 균질화조건)는 1100˚C에서 3h 정도의 R-D 반응이 필요하며, 이 확산반응이 전체반응에 있어서 율속단계임을 알았다. Sm-Fe 계의 금속간화합물들의 성장은 1000˚C이하에서는 SmFe2, SmFe3,Sm2Fe17금속간화합물의 3개의 상이 관찰되었으나, 1100˚C에서는 Sm2Fe17 금속간화합물의 상만이 관찰되었다. 본 연구에서 얻어진 최종시료의 산소 및 Ca량은 각각 0.72wt% 및 0.11wt%이었다.