Study of the Interaction Processes of Ti-Containing Solders with Oxide Ceramics and Kovar
O. M. Kostin, Al. V. Labartkava, V. A. Martynenko
F.D. Ovcharenko Institute of Biocolloidal Chemistry, NAS of Ukraine, 42 Academician Vernadsky Blvd., 03142 Kyiv, Ukraine
Received: 15.01.2014; final version - 03.04.2014. Download: PDF
The ceramic—metal products such as pressure seals of electron-beam welding vacuum plants are widely used in modern industry. These seals are fabricated by brazing or diffusion welding. Fabricating this type of units, one should take into account a number of issues connected with presence of residual welding stresses caused by difference between linear thermal-expansion coefficients of metal and ceramic as well as poor ceramic surface wetting with brazes. Therefore, matching materials and brazes with high adhesive activity are used in pressure seal constructions to decrease residual stresses and improve brazing quality. However, the features of braze wetting and flowing on kovar and ceramics are not enough presented in literature, and no results of detailed studies of phase composition and features of soldered joints using brazes and alloys based on Cu—Ti system are presented. In this paper, we examine features of wetting with STEMET-1203 braze and Cu—Ti braze, which is formed during contact-reacting soldering of titanium and copper foil (50% Ti by 50% Cu in volume), kovar 29NK, ceramics VK 94-1 and mullite (3Al$_{2}$O$_{3}$—2SiO$_{2}$), study the features of brazed joint to optimize soldering technologies for pressure seals of metal-ceramics electron-beam gun high-voltage vacuum plants for welding and sputtering. Based on obtained results, we can conclude that the kovar 29NK—ceramics VK 94-1 combination is optimal for metal-ceramics pressure seal production. The usage of pressure seal soldering with braze Ti—Cu enables to improve adhesive activity in comparison with STEMET-1203 braze and to reduce the soldering temperature by 60—90°C. Thereby, hardness is gradually increasing from kovar to ceramics and thus may promote the inherent-stresses’ level decrease in brazed joints. The chemical-elements’ pattern in brazed joint promotes formation of fast plastic seam without noticeable macro- and microdefects. The quality of metal-ceramics pressure seal brazing is determined with joint vacuum tightness and electrical resistance between ceramics and metal elements of detail. In this case, the braze impermeability is confirmed by mass-spectrometric method. The electrical resistivity between ceramics and metal pressure seal elements is over 15 G$\Omega$ at the 1 kV voltage.
Key words: chemical composition, phase composition, microhardness, wetting, flowing, oxide ceramics, Kovar, Ti-based brazes, pressure seal, active brazing.
URL: http://mfint.imp.kiev.ua/en/abstract/v36/i06/0815.html
DOI: https://doi.org/10.15407/mfint.36.06.0815
PACS: 07.30.Hd, 07.30.Kf, 81.05.Je, 81.05.Mh, 81.20.Vj
Citation: O. M. Kostin, Al. V. Labartkava, and V. A. Martynenko, Study of the Interaction Processes of Ti-Containing Solders with Oxide Ceramics and Kovar, Metallofiz. Noveishie Tekhnol., 36, No. 6: 815—827 (2014) (in Russian)