Patent ID: 6878464

Claim:
A glass-ceramic composite material comprising a glass powder and an alumina-containing ceramic powder, wherein the glass powder comprises: about 30 to 60 mol % of a silicon oxide calculated as SiO 2 ; about 20 to 40 mol % of a barium oxide calculated as BaO; 0 to about 40 mol % of a magnesium oxide calculated as MgO; 0 to about 40 mol % of a zinc oxide calculated as ZnO; 0 to about 20 mol % of a boron oxide calculated as B 2 O 3 ; wherein the total content of MgO and ZnO is about 10 to 40 mol %; wherein the content of the glass powder is at least about 50 wt % with respect to the entire amount of the glass powder and the ceramic powder; and wherein the glass-ceramic composite material is capable of precipitating a BaO.Al 2 O 3 .2SiO 2 (BaAl 2 Si 2 O 8 ) crystal phase in a compact obtained by sintering the mixture of the glass powder and the ceramic powder at a temperature of at least 850° C. and the percentage of alumina crystal phase in the sintered compact is at most half of the percentage of the alumina powder in the unsintered material, and wherein said glass-ceramic composite material further comprises a positive amount of up to about 3 parts by weight of a copper oxide calculated as CuO by weight of the glass powder and the ceramic powder.