Effect of La2O3-MgO ratio on the microstructure and properties of Si3N4 ceramics fabricated via digital light processing

Due to the low powder content characteristic of digital light processing in the preparation of ceramic green bodies, significant challenges arise in obtaining high-density, high-performance Si3N4 ceramic. Sintering aids exert a critical influence on the densification and properties of Si3N4 ceramics. To further improve the performance of 3D-printed Si3N4 ceramics, Si3N4 ceramics were fabricated using DLP technology combined with gas pressure sintering employing different ratios of La2O3-MgO as sintering aids. The ceramic slurries, microstructures, and ceramic performance were studied systematically. The results showed that increasing the proportion of & sdot; La2O3 powder enhanced the rheological and curing properties of Si3N4 ceramic slurries. Varying the La2O3- MgO ratio affected the composition of the liquid phase, leading to differences in the densification and grain growth of Si3N4 ceramics. The average grain size increased with higher ratios of La2O3-MgO, and reached a maximum value of 0.91 mu m with a ratio of 9:1. With the increase of the La2O3-MgO ratio, the bulk density and shrinkage rate of the ceramics initially increased and then declined. In addition, the flexural strength and fracture toughness of the ceramics peaked at a ratio of 3:7 for La2O3-MgO, measuring 577 +/- 16.28 MPa and 5.84 +/- 0.17 MPa m 1/2 , respectively. These results demonstrate that high-performance Si3N4 ceramics can be effectively prepared using DLP technology by adapting the ratio of sintering additives.