Abstract: The invention relates to a composite body comprising a first part of ceramic material, a second part of metallic material, of ceramic material or of a mixture of metallic and ceramic material, and a third part of a melting ceramic which seals together the first and second parts, and comprises a frit of Al.sub.2 O.sub.3 and either one or more alkaline earth metal oxides or one or more rare earth metal oxides or a combination of these two oxides. According to the invention, the melting ceramic contains a filler material which occupies at least 20% and at most 50% of the volume of the melting ceramic.

Abstract: The invention relates to a composite body comprising at least a first part of ceramic material which is connected to a second part of metallic material, of ceramic material or of a mixture of metallic and ceramic material by means of a connection material. The connection material contains besides Al.sub.2 O.sub.3 also one of the oxides BaO, SrO, Sc.sub.2 O.sub.3, Y.sub.2 O.sub.3 and at least one rare earth oxide and has a composition lying within the following limits, expressed in mol. %:Al.sub.2 O.sub.3 : 30-70BaO: 0-20SrO: 0-20Sc.sub.2 O.sub.3 : 2-40Y.sub.2 O.sub.3 : 2-40rare earth oxide: 5-40.According to the invention, the connection material further contains 5-30 mol. % of HfO.sub.2. Thus, the formation of .beta.-aluminate during the formation of the composite body is avoided.

Abstract: The invention relates to a high-pressure discharge lamp provided with a discharge vessel having a ceramic wall and a ceramic end plug which is arranged therein by means of sintering in a sunken position and in which a current-supply member of a main electrode is arranged in a gas-tight manner by means of a sealing ceramic connection. Outside the discharge space enclosed by the discharge vessel, a ceramic filling piece is arranged, which adjoins with a capillary intermediate space the wall of the discharge vessel, the end plug and the current-supply member. The capillary intermediate space is filled substantially entirely with sealing ceramic. With this construction of the vessel end, the sintered joint between the wall of the discharge vessel and the end plug is completely covered by sealing ceramic and the sealing ceramic is prevented from extending into the discharge space.

Abstract: Composite body, a gas discharge lamp having a sodium pressure from 300-600 torr in particular, having an envelope of densely sintered aluminium oxide or of other sodium vapor-resistant materials and a feed-through member of tantalum, niobium or other metals equivalent thereto, the bonding material consisting of a finely dispersed polycrystalline product having a composition in mole % between the following limits:Al.sub.2 O.sub.3 --5-70at least one oxide chosen from Sc.sub.2 O.sub.3 and Ti.sub.2 O.sub.x, wherein2<.times.<4--2-70and at least one oxide chosen from:Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3, Tb.sub.2 O.sub.3, Dy.sub.2 O.sub.3, Ho.sub.2 O.sub.3, Er.sub.2 O.sub.3, Eu.sub.2 O.sub.3, Pr.sub.2 O.sub.3, Ce.sub.2 O.sub.3, Sm.sub.2 O.sub.3, Tm.sub.2 O.sub.3, Yb.sub.2 O.sub.3, Lu.sub.2 O.sub.3, La.sub.2 O.sub.3 and Nd.sub.2 O.sub.3 --10-80.