Effects of low-melting-point sintering aid MoO3 on the performance of SiC ceramic membrane supports and the underlying mechanisms

Silicon carbide (SiC) ceramic membrane supports, as critical components of ceramic membrane filters, must exhibit outstanding performance in mechanical properties, porosity, and chemical stability. In this study, MoO₃ was employed as a sintering aid, with SiC and α-Al₂O₃ serving as raw materials and walnut shell powder as a pore-forming agent. The effects of varying sintering temperatures (1250–1400°C) and MoO₃ contents on the properties of SiC porous ceramic membrane supports were systematically investigated. Special emphasis was placed on elucidating the mechanisms by which MoO₃ addition influences porosity, flexural strength, pore size distribution, and chemical stability. Experimental results demonstrate that the introduction of MoO₃ facilitates low-temperature sintering of SiC supports through a dissolution-precipitation mechanism. This process promotes the formation of mullite whiskers that reinforce interparticle necking regions while enhancing the uniformity of neck connections. Optimal performance was achieved at 1350°C with 8 wt% MoO₃ addition, yielding a bending strength of 37.01 ± 1.72 MPa, average pore size of 1.735 μm, most probable pore size of 1.7 μm, open porosity of 39.12 %, and exceptional corrosion resistance. This work establishes both theoretical foundations and practical strategies for low-temperature fabrication of high-performance SiC porous ceramics, while expanding the application potential of molybdenum-based sintering aids in structure-function integrated ceramic materials.