微粉末圧粉体の焼結による変形の予測

Abstract

We developed a novel observation technique for density distribution of fine powder compact with an acoustic microscope. Carbonyl nickel powder was compacted under pressure of 98-392MPa as standard specimens to measure green density (GD) and dimensional change in parallel and perpendicular to the pressing direction (DC ?? and DC⊥, respectively) and of 98-294MPa as specimens to observe surface acoustic image. Subsequently, all the specimens were sintered at 1073K for 3.6ks in hydrogen atmosphere. Calibration curves of GD and DC⊥ vs. echo intensity were calculated from relationship between GD, DC ?? and DC⊥ of standard specimens. Then, the calibration curves were used to convert acoustic images into GD distribution maps, DC ?? maps and DC⊥ maps. As the results of comparisons of deformation of sintered compacts and prediction in the DC⊥ maps, obvious correlations between them were seen. As the DC⊥ map is different expression of the GD distribution map, therefore, it is capable to use the GD distribution map that effect of the GD distribution on dimensional change, i.e. deformation of sintered fine powder compact is discussed before sintering.