Effects of ZrO2 on the Nitridation Behavior and Mechanical Properties of Reaction-Bonded Si3N4/h-BN Composite

This paper presented a rapid nitridation route to fabricate reaction-bonded Si3N4/h-BN ceramic composite by the addition of ZrO2. The effects of ZrO2 on the silicon nitridation behavior, microstructure, and mechanical properties of the composite were investigated. The results showed that ZrO2 could effectively promote the nitridation of silicon and significantly influence the microstructure and mechanical properties of the composite. The best nitridation result, almost full conversion, was achieved when the ZrO2 content was 8 wt.%, and the outstanding mechanical properties were also exhibited at this condition. TG-DTA and thermodynamic analyses revealed that the inter-conversion between ZrO2 catalyst and ZrN metastable phase could effectively inhibit microzone melting of silicon and make the fresh surfaces of silicon particles exposed to nitrogen, and consequently accelerated the nitridation of silicon.