Effects of ion implantation on the brazing properties of high purity alumina

• Published in: Surface & coatings technology 2012-01, Vol.206 (8), p.2098-2104
• Main Authors: Xia, Haiyang, Wu, Aiping, Fan, Yinglong, Zou, Guisheng, Ren, Jialie
• Format: Article
• Language: English
• Subjects: Active brazing; Alumina ceramics; Applied sciences; Brazing. Soldering; Ceramics–metal joints; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Inactive brazing; Ion implantation; Joining, thermal cutting: metallurgical aspects; Materials science; Metals. Metallurgy; Other surface treatments; Physics; Production techniques; Surface treatment; Surface treatments
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2011.09.034

In this study, ion implantation was used as a surface modification method for active and inactive brazing of alumina ceramics to metals. Alumina was implanted with Ti ions at acceleration voltages of 35 kV and 55 kV at doses ranging between 2 × 10 17 and 1 × 10 18 ions/cm 2, with Ni ions at an acceleration voltage of 55 kV at doses ranging between 2 × 10 16 and 6 × 10 17 ions/cm 2, and with Al ions at 55 kV with a dose of 2 × 10 17 ions/cm 2. After implantation, the brazing of alumina to Nb was performed using the active brazing metal Ag 70Cu 27Ti 3 (wt.%) at 850 °C/870 °C and the inactive brazing metal Ag 72Cu 28 (wt.%) at 830 °C in a vacuum respectively. The surface properties of implanted alumina, e.g., implanted ions depth and concentration distribution, newly formed phases, sheet resistance etc., were studied by Rutherford backscattering (RBS), Glancing X-ray diffraction (GXRD) and four-probe method. Shear strengths of the active and inactive brazing joints were measured. Microstructures of the joints were analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). There is no obvious evidence that Ti and Ni ion implantation can enhance the quality of active brazing joints. However, it has been found that Al ion implantation can significantly increase the shear strengths of active brazing joints to average value 139 MPa, which is 30% greater than in non-ion implantation (107 MPa). It has also been found that ion implantation can improve the shear strengths of alumina–Nb inactive brazing joints. Maximum average shear strength of the inactive brazing joints can reach 43 MPa when Ni ions were used at an acceleration voltage of 55 kV in a dose of 2 × 10 17 ions/cm 2. Finally, the effects of ion implantation on alumina–Nb active and inactive brazing were discussed. ► Al ion implantation into alumina can enhance the active brazing joints of alumina to metal. ► The effects of ion implantation on the active brazing of alumina to metal are first studied. ► The surface energy change of alumina induced by ion implantation is the key to the inactive brazing of Ni implanted joints.