石墨抗氧化SiC涂层的制备与性能研究

Preparation and oxidation behavior of SiC coating for graphite materials

摘要:

本文以SiC、Si和酚醛树脂为主要原料,通过浸涂和气相渗硅两步法在石墨表面制备了SiC抗氧化涂层。利用XRD、SEM研究了涂层的相组成与形貌。结果表明,气相渗硅后涂层的主相为α-SiC,β-SiC和Si,其中Si是气相渗硅过程中残留的。涂层与基体之间具有过渡结构,致密度良好。抗氧化和抗热震实验表明：由气相渗硅工艺制备的SiC涂层结构致密,具有良好的抗氧化性能,1200℃空气条件下氧化16 h后试样每小时增重量约为2.18 mg/cm₂。涂层具有良好的抗热震性能,经1000 ℃—室温循环热震15次后试样质量变化百分率仅为-0.17%。

Abstract:

SiC coating for protecting graphite materials against oxidation was prepared using SiC, Si and thermosetting phenolic resin as materials by vapor silicon infiltration process(VSI). SEM and XRD showed that a dense SiC coating was obtained with a C/SiC gradient inner layer acting as bonding layer and combined well with the outlayer SiC coating , the main phases of coating consisted of α-SiC, β-SiC and Si, and free Si was residual after the VSI process. The as-obtained SiC coating can effectively protect graphite after oxidation for 16 h at 1200 ℃ with a weight gain about 2.18 mg/cm₂ in air and endured the thermal shock between 1000℃ and room temperature for 15 cycles with only 0.17wt% weight loss.