SiC/SiCf复合材料在高温高压水中腐蚀行为的原位拉曼光谱研究

In-Situ Raman Spectroscopy Investigation of Corrosion Behavior of SiC/SiCf Composite in High-temperature and High-pressure Water

利用高温高压循环水腐蚀试验系统、原位观察高压釜以及拉曼光谱表征系统,针对SiC/SiCf复合材料开展了腐蚀试验以及原位拉曼光谱测量。水化学介质为含1 200mg/L H3BO3和2mg/L LiOH的混合水溶液。试验分为未控氧条件(O2≈2 688μg/L)和控氧条件(O2≈5μg/L)。结果表明:在500、590、715、785、805、870、915、960cm^(-1)附近位置出现拉曼光谱峰,分别来自于β-SiC基体及其表面生成的SiCxOy、SiO2、Si(OH)4等。未控氧条件下,表面氧化膜易转变成可溶于水的Si(OH)4,保护性差。控氧条件下,氧化膜可保持较好的稳定性,SiO2向Si(OH)4的转变得到有效抑制,提高了SiC/SiCf复合材料的耐蚀性。

Corrosion test and in-situ Raman spectroscopy measurement for SiC/SiCf composite were carried out using the established high temperature and high pressure circulating water corrosion test system,in-situ observation autoclave and Raman spectroscopy characterization system.The corrosion test environment was an aqueous solution containing 1200mg/L H3BO3+2 mg/L LiOH.Two series of corrosion experiments were conducted:in one experiment,the oxygen content in solution was not controlled(oxygen content≈2688μg/L);in the other experiment,the oxygen content in solution was controlled(oxygen content≈5μg/L).The results show that the Raman peaks were located near 500、590、715、785、805、870、915、960cm^-1,corresponding toβ-SiC matrix and its surface oxide films SiCxOy,SiO2,Si(OH)4 etc.,respectively.In the oxygen-saturated solution,surface films were prone to become Si(OH)4,which were not protective.In the oxygen-controlled solution,surface films were stable,and the transformation from SiO2 to Si(OH)4 were retarded.Therefore,the corrosion resistance of SiC/SiCf composite was improved.