Synthesis of non-equilibrium porous nano particles and its consolidation

目的：用化学浸出法制备贵金属骨架材料，并用火花等离子烧结法制备具有高比表面积的骨架材料。含Au、Ag、Pd、Pd等贵金属的各种Al基二元和三元合金经NaOH浸出后快速凝固形成骨架结构。详细研究了浸出结构的凝固状态和特征。考察了浸出固结状态的比表面积。结果:1。在Al-Pd、Al-Pt和Al-Ag-Pd合金中，通过快速凝固获得了过饱和前驱体。用化学浸出法制备骨架贵金属。它们的x射线衍射图显示出非常宽的单fcc相峰。钯基材料的骨架贵金属在前驱体中的最大比表面积约为80m^2/g。结果表明，浸出可形成纳米级颗粒。SPS能有效地形成块状多孔材料，但会使比表面积减小。经过SPS后，它仍约为10m^2/g。SPS试样的密度在4 ~ 5 g/cm^3之间。SPS试样的强度足以处理后处理。通过蒙特卡罗模拟尝试了浸出骨架结构的形成机理，但由于一些重要参数仍然未知，所以没有完成模拟。

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.