Materials Science Forum Vols. 534-536

Abstract: Feasibility of producing porous gradient structure by spark plasma sintering (SPS) process was examined. Adequate combination of porosity gradient and pore size distribution could be obtained by appropriately controlling the SPS parameter such as sintering temperature, sintering time, applied pressure, and stopper length. For the longitudinal porous gradient structure, pure W sample was prepared by specially shaped graphite mold. Stainless steel powder was employed for the radially layered porous structure with different pore size. The graded porous structure could be applied for the fabrication of W-Cu FGM by Cu-infiltration and high temperature filter with high filtration efficiency.

Abstract: agents. The glass abrasive sludges were mixed with expanding agents and compacted into pellets. These pellets were sintered in the range of 700-900oC for 20min. The sintered porous materials had a surface layer with smaller pores and inner parts with larger pores. The surface layer and pores controlled the absorption ratio and physical properties. As the expanding agent fraction and the sintering temperature increased, the porosity and pore size increased. The porous materials with Fe2O3 and graphite as the expanding agents had a low absorption ratio of about 3% or lower while the porous material with CaCO3 as the expanding agent had a higher absorption ratio and more open pores.

Abstract: The low-cycle fatigue performance and fracture of the P/M Ti-Fe-Mo-Al-Nd Alloys after sintering and forging have been studied, and the linear regression equation of low-cycle fatigue lifetime was obtained. The fatigue performances were investigated [Comment: Not quite sure what is mean by ‘objected’ here.] under two different conditions. The fatigue fracture surface was analyzed by SEM. The low-cycle fatigue behavior of the P/M titanium alloy are discussed.

Abstract: Micro-porous nickel (Ni) with an open cell structure was fabricated by a special powder metallurgical process, which includes the adding of a space-holding material. The average pore size of the micro-porous Ni samples approximated 30 μm and 150 μm, and the porosity ranged from 60 % to 80 %. The porous characteristics of the Ni samples were observed using scanning electron microscopy (SEM) and the mechanical properties were evaluated using compressive tests. For comparison, porous Ni samples with a macro-porous structure prepared by both powder metallurgy (pore size 800 μm) and the traditional chemical vapour deposition (CVD) method (pore size 1300 μm) were also presented. Results indicated that the porous Ni samples with a micro-porous structure exhibited different deformation behaviour and dramatically increased mechanical properties, compared to those of the macro-porous Ni samples.

Abstract: A novel production method for porous metal components has been developed by applying powder space holder (PSH) method to metal powder injection molding (MIM) process. The PSH-MIM method has an industrial competitive advantage that is capable of net-shape manufacturing the micro-sized porous metal products with complicated shapes and controlled porosity and pore size. In this study, the small impeller with homogeneous micro-porous structure was manufactured by the PSH-MIM method using porous compounds composed of fine stainless steel 316L powder and polymethylmethacrylate (PMMA) particle. The effects of combinations in size and fraction of PMMA particle on dimensional tolerance and variation of sintered porous specimens were investigated. It was concluded that the PSH-MIM method could manufacture commercially micro-porous metal components with high dimensional accuracy.

Abstract: The primary aim pursued by the preparation of the separation membrane is to make the membrane thinner as well as have no defects. The field-flow fractionation deposition is a new molding technology which can overcome the traditional disadvantages, such as multi-preparation, to the preparation of a great area of the separation membrane with no defects. Therefore the main ingredients which influence the appearance and performance of titanium membrane layers are investigated by a scanning electricity mirror (SEM) as well as a porous material testing instrument: powder performance prepared and confected; selection of supporting body; sintering system such as temperature and time. It is shown that the membrane thickness can be controlled at 50μm or so.

Abstract: Processing techniques for producing microcellular silicon carbide, mullite, and cordierite ceramics with cell densities greater than 108 cells/cm3 and cells smaller than 30 μm have been developed by a reaction method that incorporates a polysiloxane and reactive fillers. The techniques developed in this study offer substantial flexibility for producing microcellular ceramics whereby cell size, cell density, degree of interconnectivity, composition, and porosity can all be effectively controlled. It is demonstrated that the adjustment of filler composition enables the possibility of tailoring the composition and properties of the microcellular ceramics. The present results suggest that the proposed novel processing techniques are suitable for the manufacture of microcellular ceramics with high morphological uniformity.

Abstract: Gas atomization furnace, Sumitomo Titanium Corporation originally designed, has been producing spherical and high quality Titanium fine powder, ‘‘Tilop’. Excellent characteristics of Tilop and property of metal Ti itself (high corrosion resistance, high specific strength) have made us produce new titanium porous material, ‘‘Tiporous’. With optimization of green sheet preparation and sintering process, porous sheet of large size and wide range of thickness are produced and porous pipe and other custom made shape product are also available. Evaluation of mechanical, chemical, filtration and flow-controlling properties shows that these products have good characteristics and are applicable to various industrial fields.

Abstract: Stainless steel sludge is generated as a waste in the grinding process, and the possibility of recycling stainless steel is considered here. Generally, stainless steel grinding sludge ranging about 10,000 are generated per a year in Japan, and most of it is discarded or re-melted with scrap steel. In this study, we considered the possibility of using the stainless steel sludge as metal powder for MIM or raw material for metal foam. For the MIM process, the metal powder will need some improvement, and flotation and spheroidizing processes of the sludge are necessary. For fabrication of the metal foam, untreated sludge can be used, and steel foam about 90% porosity is produced.

Abstract: Hot gas filtration and purification is widely applied in many industrial fields, such as in power generation industry, chemical and petrochemical industry, metallurgical industry, ceramic and glass industry, environmental protection industry, etc. Gas filtration at high temperature from industrial processes offers various advantages such as increasing process efficiency, improving heat recovery and materials resource recovery, protection of downstream plant equipment, etc. At the same time, it is an advanced environment protection technology. This paper describes a newly developed metallic filter element - sintered Fe3Al intermetallics. The manufacturing process of sintered Fe3Al metallic powder and the mechanical and filtration characteristics of this filter element were investigated. In this work, the mechanism of the morphological and phase constituent changes of the Fe3Al powder during sintering were studied. The newly developed filter elements were found to have excellent corrosion resistance, good thermal resistance, high strength and high filtration efficiency. Based on these results, the potential application of the sintered Fe3Al filter elements in industrial hot gas filtration are discussed.