Design of 3D network-structured Al2(WO4)3/SiC porous ceramic preforms with low thermal expansion via powder extrusion 3D printing and their pore formation mechanisms

This study successfully fabricated a three-dimensional network-structured Al 2 (WO 4 ) 3 /SiC porous ceramic preform with low thermal expansion using “Powder Extrusion Printing (PEP) + partial sintering” method. A systematic theoretical study was conducted on the preparation process of the Al 2 (WO 4 ) 3 /SiC porous ceramic preform, exploring its pore formation mechanism and performance testing. The results show that the Al 2 (WO 4 ) 3 /SiC green body prepared by PEP exhibited no significant defects, and the organic binder enhanced the surface activity of the particles, enabling tight bonding and encapsulation between Al 2 (WO 4 ) 3 and SiC particles. After debinding, the Al 2 (WO 4 ) 3 /SiC green body completely removed the internal organic binder without structural damage or the formation of new phases. The addition of Al 2 (WO 4 ) 3 promoted the rearrangement of SiC particles and the formation of sintering necks, thereby improving the strength of the porous ceramic while significantly suppressing its thermal expansion. Furthermore, the 20vol% Al 2 (WO 4 ) 3 /SiC preform sintered at 950 °C exhibited an apparent porosity of 29%, an average thermal expansion coefficient of 3.3×10 -6 K -1 within 500 °C, and compressive strength and wear rates of 79 MPa and 9.62×10 -7 mm 3 /(N·m), respectively. Therefore, the “PEP + partial sintering” approach presents a new paradigm for manufacturing high-performance, geometrically complex SiC porous ceramic preforms.