溶融塩凍結法によるCu-Al2O3微粒子の製法

概要

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We report in the article a new process of preparing Cu-Al2O3 fine powder of good quality for 0.3 and 0.6 wt%Al2O3 dispersion strengthened alloys. In this process freeze-dry techniques are applied to the starting material of Cu- and Al-nitrates. Detailed processes are as follows: (1) Mixture of two molten salts of Cu- and Al-nitrates were atomized into liquid nitrogen bath and instantaneously freezed, (2) for dehydration kept under vacuum condition for 1 day at -70°C and kept for 1-3 day at room temperature, (3) then held for 2-5 day at 95°C where the crystal structure of (Cu, Al) nitrate changed into that of basic nitrates, (4) fired for 1 hr at 260°C in which the basic nitrates were decomposed into oxides, and (5) reduced by hydrogen gas for 2 hrs at 400°C. The powders thus obtained were treated with cold-pressing and then hot-isostatic pressing. Particle shape of powder in each step and particle size distribution of oxide after HIP treatment were observed using scanning electron microscope and optical microscope, respectively. Hardness, density and electro-conductivity of the after-HIP-treatment-samples were also measured, which were essential character for spot-welding electrode.
社団法人粉体粉末冶金協会の論文