焼結フェライトの空隙形状に関する研究(第2報)

概要

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The present study is devoted to investigate the anisotropy of the surface energy obtained by observing shapes of intragranular pores in sintered Cu 0.75Fe 2.25O 4. In the sintered samples which were annealed at the temperatures between 1050°Cand 1200°Cafter fired at 1150°Cfor 3h, the pore configuration consisting mainly of eight (111) planes and some curved surfaces was observed. In order to confirm whether or not the observed pore configuration attained the equilibrium with the surface free energy and to determine quantitatively the configuration of a given pore, the change of pore shape and pore size at various annealing conditions were examined by using R parameter. Here, R is the pore aspect ratio and it indicates a ratio of distance from the center of pore to (111) plane and to curved surface orientated to near (001) plane. From the experimental results it was recognized that the pore was in equilibrium with the surface free energy only at 1100°C. On the other hand, the pore shapes largely depended on their growing and shrinking at 1150°Cand 1200°Cand it seems that they are not in equilibrium even after the prolonged annealing. By applying Wulffs theorem to those measuring results, the ratio of surface free energy of (111) plane to that of the curved surface at 1100°Cwere calculated, being about 1.29.
社団法人粉体粉末冶金協会の論文