Shotaro Morozumi1, Kazuhiko Hamaguchi2, Masaaki Iwasaki3, Michio Kikuchi4 and Yasuhide Minonishi4
1Institute for Materials Research, Tohoku University, Sendai. Present situation: Professor Emeritus, Tohoku University
Using two kinds of PLS-Si3N4 and CVD-Si3N4 joints, bonded with Al, Ni, Ti and Zr foils, and Al/Ti/Al, Al/Ni/Al and Ni/Ti/Ni three-layer foils, respectively, at 1073-1673 K in a vacuum or ambient atmosphere in three different furnaces, examinations have been made on the structure of the reaction layer by optical microscopy, EPMA and the X-ray powder method, and the bond strength of the joints, bonded with Al and Al/Ni/Al foils, by the four-point bend test.
The results obtained are as follows: (1) Since silicon nitride may decompose in a vacuum over the bonding temperature range, the composition and structure of the reaction layer are largely dependent on the atmosphere around the specimens. (2) The composition of the reaction layer is allso dependent on the state and property of silicon nitride itself. (3) As the highest bond strength of about 200 MPa has been obtained in the joints bonded with Al foil and Al/Ni/Al three layer foils, it is considered that the fused aluminum phase may have an important role for the joining.
silicon nitride, joining, brazing, aluminum, bond strength, reaction layer
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