Effect of temperature on SiC whiskers growth of SiCw/SiC composites based on selective laser sintering and their mechanical properties

The SiC _W/SiC composites was prepared based on selective laser sintering (SLS) technology, and the effect of sintering temperature on the growing number of SiC _W/SiC whiskers was studied. According to the classical diffusion theory, the growth process of SiC whiskers at each stage was analyzed, and the relationship model between the number of whiskers and temperature was built. The growth rate of in-situ SiC whiskers was decided by V-L (Vapor-Liquid) and L-S (Liquid-Solid) stages. It is decided by L-S at 1322 ℃−1438 ℃, V-L at 1438 ℃−1458 ℃, and L-S at 1458 ℃−1600 ℃. This is mainly due to different rates of SiO and CO gases generated by PCS at different temperatures. By coupling with the model of porosity and the number of whiskers, a model between the number of SiC whiskers growth in the SiC _W/SiC composite materials and temperature-porosity was obtained, and this model has a high accuracy of more than 93%. The mechanical properties of the samples with similar volume density treated by the PIP process showed that the fracture toughness of the unit volume density was increased by 4.64%, 112.01%, and 121.37% for samples A-1, A-2, and A-3, respectively, which indicates that the SiC whiskers grow the fracture toughness and has excellent toughening effect. The model is applicable for in-situ SiC whisker microstructure based on SLS, and also for other 3D printing in-situ whisker toughening systems.