Effect of Heat Treatment Process on the Microstructure and Performance of Tantalum Sealing Joint

Ming Lian
School of Materials Science and Engineering，Shaanxi University of Science and Technology，Xi’an 710021，China;
Tian Wang
School of Materials Science and Engineering，Shaanxi University of Science and Technology，Xi’an 710021，China;
Chong Wei
Science and Technology on Thermo Structural Composite Materials Laboratory, Northwestern Polytechnical University, Xi'an 710072, China;2.School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi’an, 710072, China;3.Research & Development Institute of Northwestern Polytechnical University in Shenzhen, Shenzhen 518057, China

Abstract:

This study employs low-expansion borosilicate glass as the brazing material for creating effective seals with tantalum metal. The encapsulation of glass and tantalum is followed by a performance evaluation of the sealed components. An examination is conducted on how the heat treatment process affects the microstructure and properties of the sealing interface, proposing a formation mechanism. Subsequently, the optimal sealing process is established, with an evaluation of the joint's shear strength prepared under these conditions. Results demonstrate that the shear strength of the sealed device initially increases with rising sealing temperatures before decreasing. At 1000°C, the strength peaks at 54 MPa, while the pressure resistance approaches 10 MPa. At this temperature, leakage occurs between the glass and tantalum. Excessive sealing temperatures reduce the device's pressure resistance as the oxidation degree of the tantalum's surface heightens, leading to a thicker, more porous Ta2O5 layer that causes delamination. At 1200°C, evident delamination occurs between the metal and glass, diminishing the device's pressure resistance. Considering the sealing temperature's effects on the wetting properties and pressure resistance of Ta, the ideal temperature for sealing is determined to be 1000°C. Upon a 30-minute sealing and annealing process, the glass fully melts, reducing viscosity and enhancing flow, allowing for complete spreading and infiltration on the metal surface. Upon solidification post-annealing, maximal pressure resistance is achieved. Optimal sealing time is established at 30 minutes based on a comprehensive analysis.