Synthesis of non-equilibrium porous nano particles and its consolidation

目的：以化学浸出法制备贵金属骨架材料和放电等离子烧结法（SPS）制备高比表面积骨架材料为主要目标，对含贵金属（Au，Ag，Pd，Pd）的铝基二元和三元合金进行快速凝固，然后用NaOH溶液浸出，制备骨架材料，并对浸出后的骨架材料的凝固组织和结构特征进行了详细的研究。测定了浸出态和固结态的比表面积。在Al-Pd、Al-Pt和Al-Ag-Pd合金中，通过快速凝固得到过饱和前驱体.用化学浸出法提取贵金属。它们的X射线衍射图谱大多显示出很宽的单一fcc相峰.在测试前驱体中，Pd基骨架贵金属的最大比表面积约为80m^2/g。这清楚地表明了纳米颗粒的形成. SPS是有效的形成块体多孔材料与一些降低比表面积。SPS处理后的污泥量仍在10m^2/g左右。SPS试样的密度在4和5 g/cm^3之间。SPS试样的强度足以进行后处理.用蒙特-卡罗模拟方法对浸出形成骨架结构的机理进行了尝试，但由于一些重要参数仍不清楚，模拟结果并不完整。

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.