湿式ボールミル粉砕したα-Fe_2O_3粉の焼結特性に及ぼすボールミルからの不純物の影響

概要

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Alpha-Fe_2O_3 powder was ground by ball-mill with alumina and zirconia balls. Densification behavior with respect to both specific surface area and the amount of impurities from the balls was investigated. The onset temperature of shrinkage for the powders milled with alumina balls decreased with increasing specific surface area and decreasing impurity contents. On the other hand, the onset temperatures for the powder milled with zirconia balls increased, although the specific surface area of the powder was increased by milling. Density and microstructure of the samples sintered at 1100℃ for 10h were evaluated. Relative densities of sintered samples by the powders with 3.5 mol% and 1.1 mol% Al_2O_3 were 99.4% and 99.3%, respectively. Average grain sizes of these samples were 5.4 μm and 10.1 μm, respectively. The relative density of sintered sample by the powder with 0.7 mol% ZrO_2 was 97.8%. This value was lower than those by the powders milled with alumina balls, although there was no difference in specific surface area in these powders. This results indicates that Al_2O_3 does not influence the densification of α-Fe_2O_3, however ZrO_2 inhibits densification. The cause of densification inhibition by ZrO_2 was considered that the diffusion rate of oxigen ion is decreased by the decrease of oxigen ion vacancies, which is caused by the dissolution of ZrO_2 in α-Fe_2O_3.
社団法人日本セラミックス協会の論文
1997-04-01