In order to improve the degree of matrix densification of SiC_f/SiC composites based on liquid silicon infiltration (LSI) process, the microstructure and mechanical properties of composites according to various pyrolysis temperatures and melt infiltration temperatures were investigated.

Comparing the microstructures of SiC_f/C carbon preform by a one-step pyrolysis process at 600 °C and two-step pyrolysis process at 600 and 1600 °C, the width of the crack and microcrack formation between the fibers and matrix in the fiber bundle increased during the two-step pyrolysis process. For each pyrolysis process, the density, porosity, and flexural strength of the SiC_f/SiC composites manufactured by the LSI process at 1450–1550 °C were measured to evaluate the degree of matrix densification and mechanical properties. As a result, the SiC_f/SiC composite that was fabricated by the two-step pyrolysis process and LSI process showed an 18% increase in density, 16%p decrease in porosity, and 150% increase in flexural strength on average compared to the composite fabricated by the one-step pyrolysis process.

In addition, among the SiC_f/SiC specimens fabricated by the LSI process after the same two-step pyrolysis process, the specimen that underwent the LSI process at 1500 °C showed 30% higher flexural strength on average than those at 1450 or 1550 °C. Furthermore, under the same pyrolysis temperature, the mechanical strength of SiC_f/SiC specimens in which the LSI process was performed at 1500 °C was higher than that of the 1550 °C although both porosity and density were almost similar. This is because the mechanical properties of the Tyranno-S grade SiC fibers degraded rapidly with increasing LSI process temperature.

为了提高基于液态硅渗透（LSI）工艺的 SiC _f /SiC 复合材料的基体致密化程度，研究了不同热解温度和熔体渗透温度下复合材料的微观结构和力学性能。

比较600 °C 一步热解工艺和 600 和 1600 °C 两步热解工艺制备的 SiC _f / C 碳预制棒的微观结构、纤维与基体之间的裂纹宽度和微裂纹形成在两步热解过程中束增加。对于每个热解过程，通过 LSI 工艺制造的 SiC _f / SiC 复合材料在 1450-1550 °C 下的密度、孔隙率和弯曲强度被测量，以评估基体致密化程度和机械性能。因此，SiC _f与一步法制造的复合材料相比，由两步热解工艺和 LSI 工艺制造的 /SiC 复合材料的密度增加了 18%，孔隙率降低了 16%，弯曲强度平均增加了 150%。热解过程。

此外，在相同的两步热解工艺后通过 LSI 工艺制造的 SiC _f /SiC 试样中，在 1500 °C 下进行 LSI 工艺的试样显示出比 1450 或 1550 °C 的试样平均高 30% 的弯曲强度C。此外，在相同的热解温度下，尽管孔隙率和密度几乎相似，但在 1500 °C 下进行 LSI 工艺的 SiC _f / SiC 试样的机械强度高于 1550 °C。这是因为 Tyranno-S 级 SiC 纤维的机械性能随着 LSI 工艺温度的升高而迅速降低。