| 摘要 |
PURPOSE: To obtain a glass for ultrasonic wave retarding wire element, containing both SiO2 and Bi2 O3 , free from lead components, thus causing no environmental pollution, and improved in chemical durability. CONSTITUTION: A mixture of 15-70wt.% of SiO2 , 15-70wt.% of Bi2 O3 , 0-15wt.% of K2 O, 0-45wt.% of Cs2 O, 0.1-45wt.% of K2 O plus Cs2 O, and <=20wt.% of at least one kind of component selected from BaO, SrO, CaO, MgO, ZnO, Zr2 O, TiO2 , SnO2 , La2 O3 , WO3 , B2 O3 , Al2 O3 , P2 O5 , Li2 O, Na2 O, Rb2 O3 , Sb2 O3 , As2 O3 , and respective fluorides of the aforementioned metals constituting the corresponding oxides, is heated and melted, and then homogenized and defoamed, and subsequently molded into a specified shape to obtain the objective glass 2000-3000m/s in ultrasonic wave velocity, <=±25ppm/ deg.C in the temperature coefficient of retardation time, and <=1.0wt.% in powdered glass loss.
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