HIGH THERMAL EXPANSION CYCLOSILICATE GLASS-CERAMICS

摘要

The invention is directed to highly crystalline, frit sintered glass ceramic compositions having a coefficient of thermal expansion in the range of 85 115 x 10^-7 °C. The primary crystal phases of the glass ceramics of the invention possess a cyclosilicate structure. The glass ceramic of the invention are useful as metal to metal, metal to ceramic and ceramic to ceramic sealing agents, and also as high performance coating for metals and ceramics. In their broadest composition the glass ceramic contain, in weight percent, 30-55% SiO₂, 5-40% CaO, 0-50% BaO, 0.1-10% Al₂O₃, and 0 40% SrO, wherein the sum of CaO + BaO + SrO is in the range of 35-65 wt. %. Optionally, the glass ceramic compositions may contain at least one from the group of >0 15 wt. % MgO and >0 10 wt. % ZnO. Also optionally, the glass ceramic compositions may contain >0 10 wt. % of at least one transition metal or rare earth metal oxide.