Heat-Resistant Active Brazing of Silicon Nitride Part 1: Mechanical Evaluation of Braze Joints

摘要

This paper assesses the mechanical properties of silicon nitride braze joints after fabrication and following exposure to elevated temperatures. These tests were conducted at room temperature and using four-point bending. The filler material used in the investigation is palladium-based, 58.2Pd-38.8Ni-3.0Ti. The silicon-nitride substrate was coated with a AgCulnTi filler metal prior to fabrication of the braze joint. Two different sample geometries were used in the fabrication of the braze joints. Weibull statistics was applied to the interpretation of the data, but the results contradict what is expected from monolithic fracture theories. Oxidation was found to be significant when the braze joints were exposed to 800℃ in air, which reduced the joint strength. All specimens fractured at the reaction layer during the bending tests.