繰り返し加熱処理による耐火模型材の機械的性質ならびに寸法の変化

概要

論文の詳細を見る
The porcelain restorations are fabricated by the indirect methods in which the porcelain powders are molded on the refractory investment cast and fired in the furnace. The purpose of this study is to estimate the differences in compressive strength, Knoop hardness and dimensional change of refractory investments treated with 1 to 5 times of repeated heating. It was found that compressive strength of any kind of refractory investment was decreased by 1-time heating to about half of the value of the green cast. The same tendency was observed in Knoop hardness. There were no significant differences among 2- to 5-time heating treatments either in compressive strength or in Knoop hardness. During heating, refractory investments expanded in the temperature range up to 600℃ and then tended to contract over 600℃. The materials were divided into two groups by their dimensional change patterns : one exhibitingrapid expansion at 250∿300℃ and 550∿600℃ and the other at 550∿600℃.
九州歯科学会の論文
1990-02-25