Microstructure and comprehensive properties of BN-SiC composites fabricated via oscillatory pressure sintering

BN-SiC composites with varying BN (40–70 wt%) and SiC (20–50 wt%) contents were fabricated via oscillatory pressure sintering at 1800 °C for 1 h. The results indicate that the B₅₀S₄₀Y₁₀ composites (BN/SiC=5:4) achieve a relative density of 94.65 %, flexural strength of 485.1 ± 24.2 MPa, fracture toughness of 4.87 ± 0.45 MPa·m^1/2, and Vickers hardness of 4.78 ± 0.18 GPa. These enhancements are attributed to stress-induced strengthening at BN/SiC boundaries, as well as synergistic toughening mechanisms involving BN-mediated crack bridging and SiC-induced crack deflection. Additionally, SiC-rich composites exhibit enhanced wear resistance, with wear rate decreasing to (0.93–1.15) × 10⁻³ mm³·N⁻¹ m⁻¹, approximately two-thirds reduction compared to BN-rich composites. This reduction is attributed to a transition in the wear mechanism from abrasive-dominated to oxidation-dominated wear. Furthermore, BN-SiC composites display excellent oxidation resistance due to the formation of Y₂Si₂O₇/YBO₃ protective layers on their surface which effectively inhibits oxygen diffusion into the bulk material.