The Wettability and High-Temperature Properties of Porous BN/Si3N4 Ceramics Bonded with SiTi22 Filler

The wettability and high-temperature mechanical properties of porous BN/Si3N4 ceramics brazed with SiTi22 (wt. %) filler were studied. It is manifested that SiTi22 filler presents remarkable wetting and spreading capabilities on the porous BN/Si3N4 ceramic surface. An interfacial reaction layer is generated at the interface, and the thickness of the reaction layer initially grows and subsequently remains constant with the escalation of temperature. Carbon coating modification is beneficial to the wettability and high-temperature mechanical properties of porous BN/Si3N4 ceramics. The wetting driving force is mainly controlled by the interfacial reaction at the three-phase line of the wetting front. The mechanical properties of the carbon-coated joints are significantly enhanced in comparison with uncoated joints. The joint strength attains a maximum value of roughly 73 MPa in the shear test implemented at 800 °C. The strength of the joint is significantly enhanced mainly due to the TiN0.7C0.3 particles that consume energy by changing the crack propagation direction, and the SiC nanowires strengthen the connection by bridging.