| 摘要 |
The invention provides a particulate sealing material for use in preparing hermetic seals between ceramic and cermet members, which material comprises at least 70 wt. % refractory oxide and minor quantities of non-vitreous additive comprising SiO2, MgO and B2O3. This particulate sealing material is conveniently pressed into the form of a coherent element shaped to suit the particular sealing operation concerned, e.g. the sealing of an open end of a ceramic arc tube to a cermet closure therefor. The invention also provides a method of sealing a ceramic component to a cermet member by interposing said sealing material between the opposed faces of the component and member and applying heat and pressure to sinter the sealing material and achieve a seal between the component and member. It has been observed that the sintered sealing composition in the completed seal can have a microstructure characterized by flattened refractory oxide-rich islands aligned generally parallel to said faces and substantially surrounded and interconnected by non-vitreous material rich in oxides of silicon, magnesium, and boron and said non-vitreous material forming layers thinner than said islands and also aligned generally parallel to said faces. The invention is of especial advantage in the closure of the second end of a ceramic arc tube containing volatile fill constituents, since the seal can be effected without melting of the sealing material and hence with improved retention of the tube fill constituents. |
