Synthesis of non-equilibrium porous nano particles and its consolidation

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Objectives: Synthesis of skeletal materials of noble metals by chemical leaching process and its consolidation with high specific surface area by Spark plasma sintering process(SPS) is main objectives.Various Al based binary and ternary alloys containing noble metal such as Au, Ag, Pd and Pd were rapidly solidified and then leached by NaOH to form skeletal structure.The as-solidified and characteristics of leached structure were examined in detail. The specific surface area of leached and consolidated state was also examined.Results :1. In Al-Pd, Al-Pt and Al-Ag-Pd alloys, super-saturated precursors were obtained by rapid solidification.2. Skeletal noble metals were obtained by chemical leaching. The most of their X-ray diffraction patterns showed very broad peaks of mono fcc phase.3. The maximum specific area of skeletal noble metals among test precursors was about 80m^2/g for Pd base material. It dearly suggested the formation of nano-size particles by the leaching.4. SPS was effective to form bulk porous materials with a few decreasing the specific surface area. It was still about 10m^2/g after SPS. The density of SPS specimen was in the range of 4 and 5 g/cm^3. The strength of SPS specimen was enough to handle for post processing.5. The mechanism of formation of skeletal structure by leaching was attempted by Monte-Carlo simulation but it was not completed because some important parameters were still unknown.