Abstract Partially crystallized ceramic articles is prepared by firing at low temperatures of 800 to 1100°C, a mixture consisting essentially of, (a) 40 to 50 wt.% of powdered, noncrystalline glass consisting essentially of 10 to 55 wt.% of at least one selected from the group consisting of CaO and MgO, 45 to 70 wt.% of Si0 2 , 0 to 30 wt.% of Al 2 O 3 , 0 to 30% of B 2 O 3 and up to 10% impurities, the powder size of said glass being at least 4.0 m 2 /g in terms of specific surface area measured by the BET Method; and (b) 60 to 50 wt.% of powdered Al 2 O 3 and the ceramic article is composed essentially of a noncrystallized glass phase, alumina and at least one of crystallized glass phase among anorthite, wollastonite, cordierite and mullite formed by partially crystallizing the glass (a). The ceramic articles exhibit a very high flexural strength well comparable with alumina substrate, together with greatly improved dielectric constant and thermal expansion and thus are especially useful in making multi-layer ceramic substrates for electronic applications.
A partially crystallized ceramic article which has been prepared firing at a low 0 temperature of 800 to 1100 C, a mixture consisting essentially of, in weight percentages: (a) 40 to 50% of powdered, noncrystalline glass consisting essentially of 10 to 55% of at least one selected from the group consisting of CaO and MgO, 45 to 70% of SiO 2 , 0 to 30% of A1 2 0 3 , 0 to 30% of B 2 0 3 and up to 10% impurities, the powder size of said glass being at least 4.0 m 2 /g in terms of specific surface area measured by the BET Method; and (b) 60 to 50% of powdered Al 2 O 3 .
Claim 2
Dependent Claim
120 words
A partially crystallized ceramic article which has been prepared firing at a low 0 temperature of 800 to 1100 C, a mixture consisting essentially of, in weight percentages: (a) 40 to 50% of powdered, noncrystalline glass consisting essentially of 10 to 55% of at least one selected from the group consisting of CaO and MgO, 45 to 70% of SiO 2 , 0 to 30% of A1 2 0 3 , 0 to 30% of B 2 0 3 and up to 10% impurities, the powder size of said glass being at least 4.0 m 2 /g in terms of specific surface area measured by the BET Method; and (b) 60 to 50% of powdered Al 2 O 3 .
Claim 3
Dependent Claim
40 words
A partially crystallized ceramic article as claimed in Claim 1 which consists essentially of a noncrystllized glass phase, alumina and at least one of crystallized glass phase among anorthite, wollastonite, cordierite and mullite formed by partially crystallizing said glass (a).
Claim 4
Dependent Claim
69 words
A partially crystallized ceramic article as claimed in Claim 1 in which said glass (a) was prepared by melting CaO, MgO, Si0 2 and Al 2 O 3 , or their corresponding carbonates or hydroides, at a temperature of 1300 to 1450 °C to form molten glass, then pouring the molten glass into water to obtain glass frit and then milling the glass frit to obtrain the glass (a).
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