Joining of ceramics by glass solder
The joining of ceramics components can be performed by different methods. The joining by commercial metal solders requires an extensive technical metaillization of the joined surfaces well in advance. The high temperature stability of such joints is limited by the melting point of each alloy, and at present, it usually corresponds with the highest current working temperature of less than 800 deg C. In recent years, the active solder method has been applied more frequently, which means flux-free joining without previous metallization. The working temperature usually is in the range of commercial metal solders. At present, research is focussed on the production of high-temperature resistant joints (>800 deg C). In the following, the soldering by glass solders and joining by a ceramic foil are presented as alternative to two further joining methods. Using these joining techniques enable the production of ceramics/ceramics-, glass ceramics/glass ceramics- and metal/ceramics bonds. Basis on this joining techniques it will be shown the possibility to creat a precision aerostatic guide of high performance which units the advantages of the aerostatic guide with the properties of ceramics. The investigations have shown the possibility to produce high-temperature stable, high vacuum tight and mechanically stable alumina joints. For a high strength the expansion adaption and a good wettability and the conditions of the soldering process are important. For the joining by glass solders, the following fundamental factors are important: good interfacial chemical bonds at the interfaces, closely matched coefficient of thermal expansion, particularly in the temperature range below Tg, the chemical composition and properties of the solder, the strength and the surface quality of the joined materials.