Analysis of the brazing joints of tubular zirconia ceramics and 06Cr19Ni10 stainless steel tubes

The gas-tight joining between yttrium-stabilised semi-closed zirconia ceramic tube and 06Cr19Ni10 stainless steel tube was achieved by using a self-made Ag–27Cu–4Ti paste filler material, where the joint form was an outer sleeve joint. After brazing, the samples were subjected to thermal shock (−50°C to 150°C) and thermal cycling tests (room temperature to 600°C), respectively. The sealing tightness of samples with different assembly clearances was investigated. Microstructure and phase composition of the joint with good performance was analysed. The results showed that the sealing performance of samples with the clearances of 0.03∼0.04 mm was best, and their tightness could still be less than 5 × 10−10 Pa·m3 s−1 after a series of heat treatment; microstructure of the joint with good sealing was dense and there were no obvious defects; the joining layer adjacent to ceramic was mainly comprised of three continuous reaction layers, the composition phase of which included Ti3Cu3O, TiO and ZrTiO4.