| 摘要 |
PROBLEM TO BE SOLVED: To obtain a preform capable of easily giving a molded product small in thermal expansion coefficient by compaction-molding the mixture of glass powder as base glass with an inorganic filler having smaller thermal expansion coefficient than that of the base glass to form composite glass compacted molding. SOLUTION: A mixture of glass powder as base glass with an inorganic filler having smaller thermal expansion coefficient than that of the base glass is compaction-molded, or the mixture, a organic binder, etc., are mixed, kneaded and molded. The molded product is baked to obtain the composite glass 12 where the inorganic filler 11 is dispersed in the base glass 10, and the composite glass 12 is used as a preform for molding. The base glass 10 preferably contains an alkali metal compound, and has a breakdown point of <=600 deg.C. The inorganic filler 11 is preferably quartz glass, cordierite, etc., which has thermal expansion coefficients of about 10×10<-7> / deg.C, respectively. The inorganic filler 11 is preferably added in an amount of about <=70wt.%. Thereby, molded products having an average thermal expansion coefficients of <40×10<-7> / deg.C at a temp. of -50 to +100 deg.C can be obtained.
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