This research reports for the successful consolidation of Al2O3 powder with retained ultra-fine structure using MPC and sintering. Measurements in the consolidated Al2O3 bulk indicated that hardness, fracture toughenss, and breakdown voltage have been much improved relative to the conventional polycrystalline materials. Finally, optimization of the compaction parameters and sintering conditions will lead to the consolidation of Al2O3 nanopowder with higher density and even further enhanced mechanical properties.

In a manufacturing technique of the sintered filter, pressureless sintering method has good permeability, it is not need the binder and lubricant used on compacting process, so it has little contamination and it is easy to control the pore size and shape but the mechanical strength is low relatively and it is difficult that parts of complicate form are manufactured. In the case of manufacturing the filter by press and sintering method, in order to be satisfactory characteristic of un-pressed filter, in this study sintered metal filter fabricated by using 30-40mesh stainless steel 316L powder and additive agents. Porosity and structure of pores, permeability and mechanical strength of the sintered filter were investigated with the variation sintering conditions. Porosity was nearly constant about , density, permeability and mechanical strength were changed markedly with quantity of additive materials and sintering conditions.

For attaining optimum fatigue resistance of PM steels, high density levels are necessary. In this work, sintered steels Fe-1.5%Mo-0.6%C and Fe-1.5%Cr-0.2%Mo-0.6%C were produced with density levels of 7.1 to . Ultrasonic fatigue testing with 20 kHz was performed in push-pull mode up to 10E9 cycles. It was shown that the fatigue endurance strength is strongly improved by higher density levels, but also higher sintering temperatures are beneficial. The Cr-Mo steels proved to be superior to the plain Mo alloyed, due to a more favourable as-sintered matrix microstructure.

For the purpose of investigating the effect of sintering atmosphere and carbon addition on sintered density and microstructural characteristics, the M3/2 grade high speed steel powders with the addition of carbon are sintered in vacuum and gas atmosphere. With the addition of 0 wt%C, 0.45wt%C and 1.15 wt%C the optimum sintering temperatures decrease down to , and respectively for the vacuum sintered specimen, and also decrease down to , and for the gas sintered specimen. The threshold temperatures for full densification decrease steeply with increasing carbon content of the sintered specimen, while this temperatures are slowly decreased at high carbon content. The vacuum sintered specimen shows the primary carbides of MC and type at the optimum sintering temperature, and eutectic carbides of and Fe-Cr type are produced in the oversintered specimen. The gas sintered specimen exhibits M6C and Fe-Cr type primary carbides at the optimum sintering temperature. The eutectic carbides of and Fe-Cr type and MX type carbonitride are shown for the oversintered specimen in the gas atmosphere. The hardness of gas sintered specimen shows high value of 830-860 Hv due to the increment of carbide precipitation.

In most of sintered metal powder compacts, the sintered density distribution is controlled to be as high and uniform as possible to ensure the required mechanical properties. In general, the density distribution in the compacts is not uniform and not easy to measure. In the present study, a method for measuring the density distribution was developed, based on the indentation force equation by which the hardness and the relative density were related. The indentation force equation, expressed as a function of strength constant, workhardening coefficient and relative density, was obtained by finite element analysis of rigid-ball indentation on sintered powder metal compacts. The present method was verified by comparing the predicted density distribution in the sintered Fe-0.5%C-2%Cu compacts with that obtained by experiments, in which the density distribution was directly measured by machining the compacts from the outer surface progressively.

An investigation was performed to apply the M3/2 grade high speed steel for metal injection molding using both prealloyed and elementally blended powders. The injected samples were subjected to a debinding step in gas atmosphere at a ratio that affected the carbon content of the material. The carbon content ranged from 1.4wt.% to 1.43wt%. with increasing content up to 80% in atmosphere for the prealloyed powders. The carbon contents of the elementally blended powders exhibited 1.44wt.% and 1.62wt.% at 10% and 20% gas, respectively. This level decreased to 0.17wt.% upon increasing the content. The sintered density of both powders increased rapidly as the temperature reached the liquid phase forming temperature. After forming the liquid phase, the density rapidly increased to the optimum sintering temperature for the prealloyed powders, whereas the density of mixed elemental powders goes up slowly to the optimum sintering temperature. The optimum sintering temperature and density are 126 and 97.3% for the prealloyed powders and 128 and 96.9% for the elementally blended powders, respectively. The microstructure of the specimen at the optimum sintering temperature consisted of fine grains with primary carbides of MC and type for the prealloyed powders. The elementally blended powders exhibited coarse grains with eutectic carbides of MC, and type.

지금까지 개발된 대부분의 세라믹 담체의 재료는 크게 알루미나와 실리카의 두 부류로 나누어지는데 소다유리를 원료로 하는 실리카 담체는 800℃ 정도의 온도에서 소결시켜 제조하나, 알루미나 원료의 담체는 1,300℃이상의 고온에서 소결 제조하여 원재료 및 제조비용이 높아 상업적 이용에 있어 경제성이 비교적 낮다는 단점이 있다. 따라서 본 연구개발은 소성을 하지 않고 무소성으로 압축강도가 향상된 세라믹담체를 제조하고 오염물질을 제거할 수 있는 미생물을 담체 제조시에 같이 혼합 제조하여 미생물담체를 제조하는 것이 1차 목표이며 다음으로 담체를 이용하여 수질오염물질을 제거하는 장치를 개발하는 것이다. 세라믹 담체의 원료가 되는 천연재료에 대한 녹조저감성능에 대한 시간대별로 흡착성능실험을 실시하고 이를 통해 녹조저감에 가장 우수한 재료을 선택하여 무소성 미생물 세라믹 담체를 개발 및 제조하였으며 비표면적과 흡수율, 압축강도, 미생물 균밀도에 대한 성능을 검사하였다. 또한, 개발된 세라믹담체의 수처리 효율을 분석하기 위해 Lab scale과 Pilot plant의 규모로 T-N, T-P, Chl-a, BOD 제거효율을 수질오염공정시험기준에 의거하여 분석하였다. 향후 무소성 세라믹 담체의 제조원료로 하수처리장에서 나오는 슬러지 및 다른 폐기물 등을 활용할 경우 폐기물의 재자원화와 생산단가 절감 등의 효과를 얻을 수 있을 것으로 판단된다.