Distribution and chemistry of phases developed in the brazing of silicon nitride to molybdenum

Silicon nitride was brazed to molybdenum using two different nickel-based b razing alloys. The alloys used were AWS BNi-5 (Ni-18Cr-19Si at%) and an all oy with the same Ni/Cr ratio as BNi-5 bur with 10 at% Si. Brazing experimen ts were carried out at 1220 and 1300 degrees C for times ranging from 1 to 10 min. The quality and microstructure of the S3N4/Mo couples were strongly influenced by the composition of the joining alloys, brazing time and temp erature. Microchemical analysis revealed an elaborate joint microstructure with the formation of complex reaction products in the interface. Joint str engths of up to 50 MPa were achieved when these materials were brazed with an alloy containing 10% Si. (C) 1999 Elsevier Science Limited. All rights r eserved.