| 摘要 |
PROBLEM TO BE SOLVED: To obtain a frit capable of carrying out its press forming by adding boron oxide to a rare earth oxide, alumina and silica and using ethyl cellulose as a binder. SOLUTION: Re2O3, Al2O3 and SiO2 which are raw materials are mechanically pulverized and mixed. A powder of B2O3 is then added thereto, further mixed, melted at about 1,500 deg.C beforehand and sintered. The resultant raw material is repulverized, sieved and graded. The amount of the B2O3 added is preferably 1.0-3.0 wt.% and the B2O3 may be added as an external compounding to the mixture or may be replaced with a part of SiO2. Ethyl cellulose as a binder in an amount of 0.5-10 wt.% is added and mixed therewith. The resultant mixture is then dried, sieved and further graded. The particle diameter of the graded particles is preferably 59-256μm. The resultant particles are finally press formed according to the shape of a sealing part. A debinder treatment is subsequently conducted in the atmosphere at 700-1,200 deg.C. The mixing ratio of the rare earth oxide to alumina is preferably >=70 wt.%.
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