ZrO2 reinforced porous Si3N4-based ceramics with improved mechanical properties fabricated via vat photopolymerization (VPP)

Porous Si3N4 ceramics are widely applied in many fields owing to their excellent properties such as high electromagnetic wave permeability, oxidation resistance, and wear resistance. Besides, the vat photopolymerization (VPP) technique can fabricate porous Si3N4-based ceramics with complex shapes and high precision. Nevertheless, The high absorptivity and refractive index of Si3N4 to ultraviolet light make it difficult to form porous Si3N4-based ceramics with the VPP technique. In this work, the addition of ZrO2 simultaneously improved the printability of Si3N4 slurries and the performance of Si3N4 ceramics via VPP technology. Rheological behavior and curing properties of the slurries were investigated, and the influence of ZrO2 content on the mechanical properties of printed Si3N4-based ceramics was investigated systematically. The addition of ZrO2 decreased the UV absorptivity of composite powder, thus improving the curing depth from 25.2 +/- 2.6 mu m to 64.8 +/- 3.7 mu m. XRD analysis revealed that ZrO2 in the composite ceramics mainly exists as the phase of yttria-stabilized tetragonal zirconia (Zr0.92Y0.08O1.96), which could ensure the effect of phase transformation toughening. With the increase of ZrO2 content, flexural strength and fracture toughness of porous Si3N4-based ceramics exhibited a trend of increase first and then decrease. As ZrO2 content increased to 10 wt%, the flexural strength and fracture toughness of porous Si3N4-based ceramics were improved from 214.7 MPa and 4.23 MPa center dot m1/2 to 345.0 MPa and 5.69 MPa center dot m1/2, respectively. Therefore, this work provided an important reference for the fabrication of highperformance porous Si3N4-based ceramic components with complex structures.