Silver Brazing of SiC Ceramics to Metals by using Chromium Metallization (Report 3)

Abstract

In a new Chromium (Cr) metallization process, effects of thickness of the Cr metallized layer and reaction products in that layer on the bond strength and Helium leak rate of the brazed layer were investigated.
The results of this study are as follows,
(1) The bond strength and Helium leak rate of the brazed layer were influenced considerably by the thickness of the Cr metallized layer and the reaction products in the metallized lyer
(2) A high bond strength and very small Helium leak rate were obtained when the thickness of Cr metallized layer was between 0.6 μm and 2μm.
(3) The reaction products were guessed as a complex compound (Cr.Si.C) and Cr silicide (Cr₃Si₂) from the SiC side when the thickness of Cr metallized layer was 1.4μm. The reaction products were the same as that when the thickness of metallized layer was 6μm. But the grain sizes of reaction products ranged from 0.07 μm to 0.18μm when thickness of Cr metallized layer was 1.4μm. Those reaction products were about 1/10 in grain size as compared with that when the thickness of Cr metallized layer was 6μm.