炭纤维涂层改性对快速制备C_f/SiC复合材料力学性能的影响

Effect of carbon fiber coating modification on mechanical properties of rapidly prepared C_f/SiC composite

以 SiC 粉末、酚醛树脂粉末及有 PyC/SiC 复合涂层改性和无涂层改性的两种炭纤维毡/布为原料,采用新型快速成形工艺结合反应熔体浸渗技术制备 Cf/SiC 复合材料,并对其表面化学气相沉积(chemical vapordeposition(CVD))/SiC 涂层。通过 XRD 物相分析、扫描电镜及复合材料力学性能测试等手段,研究炭纤维涂层改性及表面涂层改性对 Cf/SiC 复合材料力学性能的影响。结果表明:涂层改性的炭纤维在反应熔渗过程中不被液Si 侵蚀,从而提高材料的力学性能;表面 CVD SiC 涂层改性能够通过填补表面缺陷,包覆易裂部位,涂层脱粘,弥补内部缺陷等方式提高抗弯强度;采用 PyC/SiC 复合涂层对炭纤维改性后,复合材料抗弯强度由 150.90 MPa提高到 217.96 MPa,通过表面 CVD SiC 涂层后,复合材料抗弯强度进一步提高,达到 266.94 MPa。

Cf/SiC composites were fabricated by new rapid forming process and reactive melt infiltration, using SiC powder, phenolic resin powder and coated as well as uncoated carbon fiber felt/cloth as raw materials. Then the surface of Cf/SiC composites were coated by chemical vapor deposition (CVD) SiC coating. The effects of coating modification of the carbon fiber and surface coating on the mechanical properties of Cf/SiC composite were studied by XRD phase analysis, scanning electron microscopy (SEM) and mechanical properties test of composite. The results show that CVD PyC/SiC composite interface coating can improve the mechanical properties of the composite materials by protecting carbon fibers from liquid Si corrosion during reactive melt infiltration. CVD SiC surface coating can improve the bending strength of Cf/SiC composite by filling surface defects, cladding fragile parts, coating debonding and remedying internal defects. The bending strength of carbon fiber with PyC/SiC composites coating increases from 150.90 MPa to 217.96 MPa. By means of CVD SiC surface coating, the bending strength is further improved to 266.94 MPa.