Designing SiC/IrSi₃ Composites for Aggressive Environments: Wetting Characteristics of the Liquid Si-Ir Eutectics in...

The design and fabrication of metal matrix materials (MMCs), as well as the densification and joining of ceramic matrix composites (CMC), are still very challenging. For SiC- and C-based composites, liquid-assisted processing routes, such as the spontaneous infiltration process, emerge among the most cost-effective processes. To succeed in Ir-Si/SiC refractory composite fabrication by spontaneous infiltration, the wetting characteristics of the Ir-Si/SiC system, the surface and transport properties (surface tension and viscosity) of liquid Ir-Si alloys, and microstructural evolution at the interfaces formed between solid SiC (or C) with Ir-Si melt, have been carefully examined. Specifically, the wettability and interaction phenomena occurring at the Si-Ir eutectics/SiC interface as a function of temperature were investigated in the temperature range of T = 1350-1400 °C by the sessile drop method under an inert atmosphere with reduced oxygen content, and the results are presented and discussed in this paper. Taking into account the thermodynamics of the Si-C-Ir system, the interfacial phenomena and subsequent microstructural evolution are well-related to the process parameters, and the properties and characteristics of the as-produced interfaces may be predicted accordingly. The experimental conditions and results of wetting experiments, together with thermodynamic-based models predicting thermophysical property values of liquid Ir-Si alloys, are valuable key input data that are now available for the numerical study of infiltration processes.