Potential mold material for precision glass molding: Highly conductive oxidation-resistant SiC–B4C ceramics

In this study, to develop a mold material for precision glass molding (PGM) with high strength, high electrical conductivity, and excellent antioxidant properties, silicon carbide–boron carbide (SiC–B 4 C) composite ceramics were prepared using a reaction sintering process. The effect of B 4 C content on the physical phase composition, microstructural characteristics, mechanical properties, electrical conductivity characteristics, and high-temperature oxidation resistance of the developed ceramic systems, successfully demonstrating the potential of SiC–B 4 C for mold application. The addition of B 4 C altered the composite ceramic’s physical phase and microstructure, significantly increasing its density. Specifically, the composite sample containing 12 wt% B 4 C exhibited 46.87 % higher compressive strength and a lower order-of-magnitude DC resistivity compared to pure SiC. This crucial reduction in resistivity enables the use of electrical discharge machining, thereby addressing the challenge of processing pure SiC molds. High-temperature oxidation experiments revealed that the sample containing 6 wt% B 4 C exhibited the best antioxidant performance, which was attributed to the formation of a borosilicate glass phase during the oxidation process. This phase formed a 19.6589-μm-thick continuous dense oxide layer on the sample surface that effectively blocked further oxygen diffusion and enhanced the self-healing capability of the composite ceramic. These results position SiC–B 4 C as a highly promising candidate for PGM mold applications.