TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: (I) comprises glassy phase obtained from the elaboration before any heat treatment. (I) comprises less than 50 (preferably 0) wt.% of crystalline phase, after its maintenance at a temperature of 600-1000 degrees C, preferably 700-900 degrees C for a period of more than 1 hour. (I) is a viscoplastic composition and has a viscosity of 107-108 dPa.s at 700-900 degrees C. The glass transition temperature of (A) is 580-620 degrees C and glass transition temperature of (B) is 600-680 degrees C. (A) comprises: silicon dioxide (72.3 mole%), B2O3 (7.8 mole%), aluminum oxide (5.9 mole%), and Na2O (14 mole%); and silicon dioxide (74.3 mole%), B2O3 (7.8 mole%), aluminum oxide (5.9 mole%), and Na2O (12 mole%). (B) comprises: silicon dioxide (66 mole%), zirconium oxide (10.1 mole%), B2O3 (5.1 mole%), lanthanum oxide (1 mole%), Na2O (13.4 mole%) and potassium oxide (4.4 mole%); and silicon dioxide (74.9 mole%), zirconium oxide (7 mole%), potassium oxide (4.2 mole%), B2O3 (5.1 mole%), lanthanum oxide (1 mole%) and Na2O (12.9 mole%). (A) is in the form of a powder or a solid block. Preferred Components: The step of contacting the parts with the glass composition is preformed by forming a powder of glass composition, by suspending the powder in an organic binder to obtain a suspension or paste, and coating at least one surface of parts to be assembled with the obtained suspension or paste. The step of contacting the parts with the glass composition is performed by preparing a part of glass in the form of the joint to be formed, and then introducing the part between the surfaces of parts to be assembled. The part of glass is prepared by compacting and sintering a powder of glass composition in a mold according to the form of glass part. The part of glass is a block of glass solid prepared by direct casting of molten glass composition in a mold according to the shape of the part of glass. Preferred Components: The parts to be assembled are a material comprising metals, metal alloys, ceramics, and composite materials including metals, metal alloys and/or ceramics. In the process, at least two parts to be assembled are of different materials. In the process, at least two parts to be assembled are parts of a high temperature electrolyzer or high temperature fuel cell. EXAMPLE - Typical glass composition comprised (mole%): composition (A) comprising silicon dioxide (72.3), boron oxide (B2O3) (7.8), aluminum oxide (5.9), and sodium oxide (Na2O) (14); and composition (B) comprising silicon dioxide (74.9), zirconium oxide (7), lanthanum oxide (1), Na2O (12.9) and potassium oxide (4.2).