碳复合材料的Si-SiO_2-SiC抗氧化涂层研究

Study on oxidation resistant Si-SiO_2-SiC coating for carbon containing material

以石墨、白刚玉、矾土熟料、α-Al2O3为主要原料制备了碳复合材料的基体试样,将基体试样置于密闭的匣钵中并用Si颗粒包埋,经1600℃1h烧成。研究发现在高温及缺氧气氛条件下,埋Si基体试样烧后,在基体的表面反应形成了Si-SiO2-SiC涂层,反应过程的体积膨胀效应增加了表面涂层的密实度。在常压、空气中,烧后试样于1300℃分别进行0.4h和5h的氧化试验,结果表明随氧化时间的延长,试样表面的Si不断氧化,形成了连续、密实的SiO2薄膜,堵塞气体侵入的通道,赋予试样优良的抗氧化性能。在涂层与基体的结合部位为富含SiC的过渡连接层,在涂层的外表面为SiO2的表面涂层,涂层为具有良好抗热震性能的功能梯度涂层。

Carbon-containing composite was made of graphite,white corundum, bauxite chamotte and α-Al2O3. put in an airproof refractory saggar and covered by Si grains,the composite specimen was then fired at 1600 ℃ for 1 h. It was found that Si -SiO2 -SiC generated on the surface of graphite crucible body under the condition of high temperature and lack of oxygen atmosphere. In addition,volume expanding effect during reaction process improved compaction degree of surface coating. With time goes on, Si was constantly oxidized on the specimen surface,forming continuous and compact SiO2film,rendering the specimen with excellent oxidation resistance. The juncture between coatings and the body was rich in SiC as transition connecting film and the exterior surface of coatings contained SiO2,which was of functional gradient coating with well-performed thermal shock resistance.