Tailoring microstructure, mechanical and tribological properties of β-Sialon ceramics via Y2O3-ZrO2 composite sintering additives design

This study systematically investigates the effects of varying Y 2 O 3 /ZrO 2 additive ratios on the phase evolution, microstructural characteristics, densification, mechanical properties, and tribological performance of β-Sialon ceramics fabricated via spark plasma sintering. The results demonstrate that both Y 2 O 3 and ZrO 2 promote the formation and densification of β-Sialon. Specifically, ZrO 2 facilitates the in-situ reaction with Si 3 N 4 and AlN to form ZrN, while Y 2 O 3 enhances the densification process through liquid phase formation. Notably, the content of in-situ formed ZrN decreases with the increase of Y 2 O 3 addition. Compared to the single addition of Y 2 O 3 , the optimized Y 2 O 3 /ZrO 2 ratio enables the formation of fine β-Sialon grains, well-dispersed ZrN particles, and minimal grain boundary phases. When 2 wt% Y 2 O 3 and 4 wt% ZrO 2 (SY2Z4) were added, the β-Sialon ceramic achieved an optimal balance of properties, where the Vickers hardness and fracture toughness reached 17.3 GPa and 6.7 MPa m 1/2 , respectively, representing increases of 27.2% and 28.9% compared to the sample with the sole addition of 6 wt% Y 2 O 3 (SY6). In terms of tribological properties, the SY2Z4 sample exhibits a significantly reduced coefficient of friction (0.582), wear volume loss (0.89 × 10 −2  mm 3 ), and wear rate (0.25 × 10 −5 mm 3 /(N·m)), which are 12.87%, 91.76%, and 91.67% lower than those of SY6, respectively. The results also indicate that abrasive wear is the dominant wear mode, and the in-situ formation of a protective tribofilm on the worn surface of SY2Z4 further contributes to its superior wear resistance. This work provides a feasible strategy for the microstructural regulation and performance optimization of β-Sialon ceramics via tailoring rare earth oxide/transition metal oxide additive systems, which holds great potential for extending their applications in high-wear-resistance engineering fields.