Improving strength and microstructure of SiC reticulated porous ceramic through in-situ generation of SiC whiskers within hollow voids.

SiC reticulated porous ceramic with excellent strength and high-density ceramic struts was successfully prepared using the polymer replica method, followed by pressureless sintering under a buried charcoal atmosphere. First, a polyurethane (PU) template was coated with a Si slurry and then a SiC-containing slurry, and subsequently heated under the buried charcoal atmosphere. To ensure excellent coating ability of the slurries, the viscosity, thixotropy, and yield stresses of the Si slurry were optimized by adjusting the content of the thickening agent. During heating, Si in the coating layer reacted with the residual C and CO gas from the PU template and buried charcoal, forming SiC whiskers that filled hollow voids within the SiC struts. Additionally, catalyst ferric nitrate was added to the Si slurry to promote the generation and growth of SiC whiskers. As a result, when compared to the untreated SiC reticulated porous ceramic, the SiC reticulated porous ceramic pre-coated with Si layers exhibited significant improvements in mechanical strength and thermal shock resistance, despite minor differences in porosity. Furthermore, an industrial test conducted in the copper smelting industry showed that the structure of SiC reticulated porous ceramic, prepared in this study and used as filters, remained intact even after 7 days of continuous use. Meanwhile, a significant number of inclusions was adhered to the surfaces of the filters. Therefore, the processes combined with in-situ generation of SiC whiskers is an ideal and low-cost method for fabricating SiC filters with excellent properties. [ABSTRACT FROM AUTHOR]