Brazing between high purity alumina ceramic and oxygen-free copper

The joints of high purity alumina ceramic and oxygen-free copper with high strength and low gas loakage are needed in electron tube.This work investigates the effects of brazing tempurature, holding time and copper matrix on the joint microstructures, shear strength and interface reactions.The joints with shear strength close to 90 MPa could be achieved by brazing with AgCuTi at the temperature of 850-900℃ and the holding time of 20-60 min. Lower or higher temperature and shorter or longer holding time are detrimental to joint strength.The joint is consisted of Cu Ag(Cu), Cu(Ag, Ti) Cu₃Ti₃O(TiO₂) Al₂O₃.The main product in the reaction layer was Cu₃Ti₃O, and TiO₂ was observed at certain parameters.The effects of copper matrix on the joint microstructures were different based on the parameters.