In this study, we report the microstructure and the high-temperature oxidation behavior of Fe-Ni alloys by spark plasma sintering. Structural characterization is performed by scanning electron microscopy and X-ray diffraction. The oxidation behavior of Fe-Ni alloys is studied by means of a high-temperature oxidation test at 1000oC in air. The effect of Ni content of Fe-Ni alloys on the microstructure and on the oxidation characteristics is investigated in detail. In the case of Fe-2Ni and Fe-5Ni alloys, the microstructure is a ferrite (α) phase with body centered cubic (BCC) structure, and the microstructure of Fe-10Ni and Fe-20Ni alloys is considered to be a massive martensite (α’) phase with the same BCC structure as that of the ferrite phase. As the Ni content increases, the micro-Vickers hardness of the alloys also increases. It can also be seen that the oxidation resistance is improved by decreasing the thickness of the oxide film.

A high temperature dilatometer attached to a graphite furnace is built and used to study the sintering behaviorof B4C. Pristine and carbon doped B4C compacts are sintered at various soaking temperatures and their shrinkage pro-files are detected simultaneously using the dilatometer. Carbon additions enhance the sinterability of B4C with sinteringto more than 97% of the theoretical density, while pristine B4C compacts could not be sintered above 91% due to par-ticle coarsening. The shrinkage profiles of B4C reveal that the effect of carbon on the sinterability of B4C can be seenmostly below 1950°C. The high temperature dilatometer delivers very useful information which is impossible to obtainwith conventional furnaces.

A new manufacturing process of Fe-Cr-Al powder porous metal was attempted. First, ultra-fine fecralloy powders were produced by using the submerged electric wire explosion process. Evenly distributed colloid (0.05~0.5% powders) was dispersed on PU (Polyurethane) foam through the electrospray process. And then degreasing and sintering processes were conduced. In order to examine the effect of sintering temperature in process, pre-samples were sintered for two hours at temperatures of , , , and , respectively, in atmospheres. A 24-hour TGA (thermo gravimetric analysis) test was conducted at in a 79% +21% to investigate the high temperature oxidation behavior of powder porous metal. The results of the high temperature oxidation tests showed that oxidation resistance increased with increasing sintering temperature (2.57% oxidation weight gain at sintered specimen). The high temperature oxidation mechanism of newly manufactured Fe-Cr-Al powder porous metal was also discussed.

Preparation processing of sintered silicon nitride ceramics was emphatically investigated with Self-Propagating High-Temperature Synthesis (SHS) of silicon nitride prepared by ourselves as raw material. The results indicate that good sinter ability can be obtained with cheaply SHS of silicon nitride preparing silicon nitride materials. The cost of silicon nitride materials will be lowered.

In this study, high purity fine powders were prepared by SHS (Self-propagating High-temperature Synthesis). We would examinate the study of sintering properties and characteristics as a function of temperature with various additives (binder, sintering agent). In separately binder addition, the green and sintered density of specimen were increased as binder content increases. The increased porosity resulted in fine grain size due to the inhibition of grain boundary moving. The and MgO playa role of increasing dielectric constants at room temperature. These values were decreased at curie temperature. In case of , the Curie temperature was decreased. In this study, a high dielectric ceramic capacitor material with temperature stability was synthesized by using various additives

본 논문에서는 1673K에서 소결한 PSZ/Ni 복합재에 대한 종 탄성계수, 파괴강도, 파괴에너지 등의 기계적 특성을 평가하기 위해, 개량형 소형펀치시험을 행한 결과에 대해 논의한다. 또한 파면관찰과 AE법을 통해 이들 재료의 고온환경에서의 미시파괴과정도 조사하였다. 시험온도는 293K, 1073K, 1273K, 1473K의 4종류로 하였으며, PSZ/Ni 복합재료의 체적 조성비도 80/20, 60/40, 40/60, 20/80의 4종류이다. 이들 실험결과로부터, 1073K이상의 고온에서 Ni 함량이 60%인 PSZ/Ni 복합재가 파괴강도 및 파괴에너지가 가장 우수한 것을 알았다. 파면관찰에 의하면 이 재료의 조성비에서 파고거동이 취성으로부터 연성으로 천이하는 것을 확인할 수 있었다.