| 摘要 |
PURPOSE:To measure the refractoriness of porcelain clay simply and with good precision by obtaining the temp. of an inflection point where the change from contraction to expansion occurs in thermal expansion measurement of a porcelain pressformed body. CONSTITUTION:Porcelain powder e.g. of <=74mum particle diameter is formed to cylindrical or cubical shape by using a pelletizing machine. The size of the formed body of about 10mm. diameter, about 3mm. height is used in a cylindrical body, and that of about 10mm. side is used in a cubical body. Said body is set in a thermal dilatometer and heated. By the heating, it expands thermally (1) up to some temp., but contracts (2) by sintering if the temp. is attained. If further the temp. is raised, since said body begins to melt at a specified temp. and vitrified, the gases generated therein can't be diffused to the outer part above the temp., and the expansion (3) is begun suddenly. The sudden inflection point is in good correlation with refractoriness by the JIS metod, and the temp. of said point is obtained as the refractoriness. |
