PRESS FORMING METHOD OF OXYNITRIDE GLASS

摘要

PROBLEM TO BE SOLVED: To find out the optimum cooling conditions under which less warped press-formed bodies are obtained without forming a crystal phase to adversely affect surface smoothness in press forming oxynitride glass. SOLUTION: After the glass is press formed, a rapid cooling process step is carried out at >=400 deg.C/hr and a slow cooling process step to cool the glass at <=100 deg.C/hr is carried out until the temperature of the glass attains a slow cooling process step end temperature T2( deg.C) after attaining the slow cooling process step start temperature T1( deg.C) and the slow cooling process step start temperature T1( deg.C) and the slow cooling process step end temperature T2( deg.C) are so set as to satisfy the following expressions; 530+10n+A<=T1<=630+10n+ A...(1) T2<=420+10n+A...(2) In the expressions, n is eq% of nitrogen when the total eq% of the nitrogen and oxygen in the glass is defined as 100 eq% and A is the value determined by a glass composition and is 0<=A<=600.