莫来石连续纤维制备工艺

Fabrication of Continuous Mullite Fibers

以微米Al_2O_3和纳米SiO_2为原料,添加成型添加剂PVB,制备出了多晶莫来石纤维。借助差热-失重分析(DSC-TGA)、X射线衍射(XRD)及扫描电镜(SEM)分别对纤维的固相反应、相组成及表面形貌等进行了研究。DSC-TGA表明,在600℃以下PVB被完全排出,在1200℃左右纳米SiO_2发生从非晶质到鳞石英的晶形转变,XRD分析显示1400℃以下没有莫来石生成,1500℃生成少量莫来石,1500℃到1600℃时,莫来石大量生成,纤维完全莫来石化,并从动力学上说明了Al_2O_3和SiO_2是一步反应生成莫来石。通过SEM观察,由于PVB的大量挥发,使制得的纤维表面粗糙,脆性增加。

Mullite fibers were prepared from the reaction of Al2O3, SiO2 and PVB, and the reactions were followed by DSC-TGA, XRD, SEM and DSC-TGA analysis. PVB escaped from the system below 600 ℃, and the change from amorphous to tridymite was detected at 1200 ℃. XRD analysis did not detect mullite from the reaction at 1400℃, with only trace amount of mullite formed at 1500 ℃. The products sintered at 1600℃, consisted of mullite and alumina. The reaction of Al2O3 and SiO2 was a one-step reaction. SEM showed the mullite fiber was coarse and brittle due to the absence of PVB.