Melt Infiltrated Ag-MAX Phase 3-D Interpenetrating-Phase Composites: Processing, Structure and Properties

Electrical contact materials are generally Ag- or Cu-based composites and play a critical role in ensuring the reliability and efficiency of electrical equipments and electronic instruments. The MAX phase ceramics display a good combination of property advantages from both metals and ceramics, and thereby may serve as an ideal reinforcement phase for electrical contact materials. Here, a series of bi-continuous Ag-Ti3SiC2 MAX phase composites with high ceramic contents exceeding 50 vol.% and having micron- and ultrafine-scaled 3-D interpenetrating-phase architectures, where the Ag and Ti3SiC2 phases were continuous and mutually interspersed, were exploited by pressureless infiltration of Ag melt into partially sintered Ti3SiC2 scaffolds. The mechanical and electrical properties as well as the friction and wear performance of the composites were investigated and revealed to be closely dependent on the ceramic contents and characteristic structural dimensions. The composites exhibited a good combination of properties with high hardness over 2.3 GPa, high flexural strength exceeding 530 MPa, decent fracture toughness over 10 MPa m1/2, and good wear resistance with low wear rate at an order of 10-5 mm3/(N·m), which were much superior compared to the counterparts made by powder metallurgy methods. In particular, the hardness, electrical conductivity, strength, and fracture toughness of the composites demonstrated a simultaneous improvement as the structure was refined from micron- to ultrafine-scales at an equivalent ceramic content. The good combination of properties along with the facile processing route makes the Ag-Ti3SiC2 3-D interpenetrating-phase composites appealing for electrical contact applications.