C/C composite surface modified by electrophoretic depositing SiC nanowires and its brazing to Nb

Abstract

A novel surface treatment method by electrophoretic depositing SiC nanowires on the C/C composite was introduced to reinforce the C/C–Nb brazed joints. Results showed that the electrophoretic deposition (EPD) process of SiC nanowires could improve the wettability of the liquid AgCuTi alloy on the C/C substrate because of the reaction between SiC nanowires and active element Ti in the AgCuTi alloy. With the introduction of SiC nanowires, the formation of continuous brittle Ti3Cu4 layer was inhibited and the Ti3Cu4 changed into lumps. The thickness of the TiC reaction layer was 500 nm when the EPD time was 5s which was larger than that of the original brazed joint. As the EPD time continued to increase, the thickness of the TiC reaction layer decreased gradually and the size of brittle Ti3Cu4 phase in the joint became smaller and smaller. With the combined effects of the change in the Ti3Cu4 morphology and the TiC reaction layer thickness, the average shear strength of joints achieved a peak of 48 MPa when the EPD time was 30s, which was 60% higher than that of the original brazed joints.