Glass powder which is crystallizable to yield a sintered glass ceramic containing hexagonal cordierite as the principal crystalline phase

摘要

A glass powder crystallizable to yield a sintered glass ceramic containing hexagonal cordierite as the principal crystal phase is of the composition, in mol % on an oxide basis, of 48-61 SiO.sub.2 ; 10- 16 Al. sub.2 O.sub.3 ; 23-35 MgO; 0-4 B.sub.2 O.sub.3 ; 0-2.5 P.sub.2 O. sub.5 ; 0.5-5 &Sgr; B.sub.2 O.sub.3 +P.sub.2 O.sub.5 ; 0-3 ZnO; 0-3 CaO; 0-1.5 BaO and as an essential component 0.5-12 F as a substitute for O. The glass powder may also contain a total of up to 3 mol % of one or more of the oxides PbO, SrO and SnO.sub.2. The glass powder can be crystallized at sintering temperatures below 970° C. in a relatively broad sintering temperature range to yield a sintered glass ceramic having excellent and constant properties. It is particularly suitable for the production of electrotechnical and electronic components since it has very good electrical, dielectrical and mechanical properties. The sintering conditions can be varied within relatively broad limits without any adverse effect on the product obtained.