Joining of SiC ceramics using high-silicon aluminum alloy fillers assisted by laser cladding

Abstract

A Si–40Al joining transition layer was prepared via laser cladding, followed by brazing of SiC ceramics using Si–60Al alloy as the joint filler. The microstructure, composition, and flexural strength of the brazed joints were investigated under different brazing temperatures and holding times. The corrosion resistance of the joints was evaluated using a hydrochloric acid immersion test. The laser cladding layer effectively reduced interfacial stress, enhanced interfacial bonding, and suppressed the formation of brittle intermetallic compounds. The main constituents of the brazed joint were Si, Al2O3, and SiC, with newly formed SiC at the interface promoting interfacial bonding. The flexural strength of the brazed joint held at 900 °C for 30 min exceeded 279 ± 13 MPa, equivalent to that of the SiC substrate. Compared to direct brazing of SiC using Si–60Al alloy filler and Si–40Al alloy filler, the strengths were increased by 49% and 94%, respectively. Furthermore, the joints exhibited excellent corrosion resistance, with a flexural strength of 177 ± 11 MPa after 10 h of hydrochloric acid immersion.