Incorporation of Carbon Into ZrO2–SiO2 Powder Through Combustion Synthesis and Its Influences on the Sintered Ceramics

The in situ formation of carbon fillers has been demonstrated as an effective strategy to eliminate the agglomeration of carbon fillers in ceramic composites. In this study, combustion synthesis was employed to in situ incorporate carbon into a ZrO 2 –SiO 2 ceramic powder using CO 2 gas as the carbon source and magnesium powder as the exothermic medium. The resulting disordered carbon is uniformly distributed within the powder matrix. Furthermore, magnesium element is simultaneously incorporated into the powder as a byproduct. The co-presence of carbon and magnesium elements synergistically enhances the solid-state reaction between ZrO 2 and SiO 2 during sintering, facilitating the formation of ZrSiO 4 at a significantly reduced temperature of 1080°C. Meanwhile, the solid-state reaction significantly promotes the densification of the ceramic composite. The incorporated carbon exhibits strong bonding with the ceramic matrix and remains stable within the matrix up to at least 1000°C. Compared with conventional ZrSiO 4 , the ZrSiO 4 phase formed in this study exhibits much lower decomposition temperature in range of 1000°C–1200°C. Molten copper exhibits pronounced corrosion toward the ceramic composite, primarily through reactions with the SiO 2 phase released from the decomposition of ZrSiO 4 .