Abstract: Short cut carbon fiber reinforced silicon carbide composite (C_sf/SiC) is a kind of high-performance ceramic matrix composite. Vat photopolymerization 3D printing can make up for the shortcomings of traditional process in the precision manufacturing of complex fine structure C_sf/SiC components. In this paper, the photosensitive resin based C_sf/SiC slurry was prepared with short cut carbon fiber (C_sf), silicon carbide (SiC) micropowder and photosensitive resin. The test strips (A and B) with the movement direction of the scraper parallel to and perpendicular to the length direction of the test strip were obtained by the Vat photopolymerization 3D printing process. The changes of bending strength, Weibull modulus, size and weight of the two kinds of test strips before and after debonding were compared. The results show that the A test strip has higher strength and structural uniformity, and its density, bending strength and Weibull modulus are 1.81 g/cm³, 10.68 MPa and 13.22, respectively. After debonding, the density, bending strength and Weibull modulus of the green body decrease to 1.40 g/cm³, 7.32 MPa and 9.45, respectively. The debonding shrinkage in X, Y, Z direction are 1.22%, 3.35% and 4.24%, respectively. The brittleness of the green body increases and the toughness decreases. The chemical vapor infiltration (CVI) process can achieve the densification, toughening and homogenization of C_sf/SiC samples. The weight of debinded C_sf/SiC samples after CVI carburization increases about 50%, and the density, compactness, bending strength and Weibull modulus are 2.02 g/cm³, 93.88%, 121.22 MPa and 21.04, respectively.

Key words: C_sf/SiC, 3D printing, Vat photopolymerization, microstructure, mechanical property, chemical vapor infiltration