酸化ベリリウム粉体の加圧焼結

概要

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Experimental data of the densification rate of BeO compacts, hot-pressed in graphite dies for 1275° to 1700°C and for 115 and 289kg/cm2, showed that the densification rate during final stage is described by;dρ/dt=10σaDΩ/R2kTρ1/2which has been derived by combination the effective stress with the Nabarro-Herring microcreep in the previous study.Plots of the densification rate vs ρ-1/2 are fitted well with two straight lines; the lower slopes represent the final stage of densification which are predicted by this theoretical equation, the higher slopes suggest diffusional transport of materials based on grainboundary diffusion and/or grain-boundary sliding.Although this densification and Murrays one, both are justified by the linear relationship in ρ3/2 vs t and -ln(1-ρ) vs t, but the former can predict a time necessary for the compact to be theoretical density, it gave more reasonable conclusion.Non linear relationship between dρ/dt and ρ-1/2 prevails in lower temperature, suggests that the densification is contributed by certain slip mode, as a basal slip, concurrent with a pore structure variation.
社団法人日本セラミックス協会の論文
1972-01-01