活性填料在聚碳硅烷先驱体转化陶瓷中的应用

比较了铝 (Al)、铬 (Cr)、二氢化钛 (TiH2 )和锆 (Zr)等活性填料在聚碳硅烷 (PCS)先驱体转化陶瓷中的应用。研究表明 ,在先驱体中加入活性填料能有效降低陶瓷素坯的气孔率 ,可与PCS气态裂解产物、游离碳和 (或 )N2 气氛反应生成新的化合物 ,提高PCS的陶瓷产率。活性填料的种类与含量对陶瓷烧成体的线收缩有较大的影响 ,Al、Cr能抑制烧成体的线收缩 ,其含量越高 ,线收缩越小。但是TiH2和Zr并不能抑制陶瓷烧成体的线收缩 ,其含量越高 ,线收缩越大。此外 ,活性填料的种类及含量对陶瓷烧成体的三点弯曲强度也有较大的影响。Al、Zr的含量越高 ,材料的强度也越大。但Cr和TiH2 的加入却使材料强度下降。认为Al是较好的活性填料。用X -衍射法 (XRD)分析了烧成产物的物相组成 ,扫描电子显微镜 (SEM)观察了陶瓷烧成体的断口形貌。

Application of Active Fillers in the Preparation of Polycarbosilane Derived Ceramics

The application of active fillers, Al, Cr, TiH 2 and Zr, in the preparation of polycarbosilane(PCS) derived ceramics was investigated. The results showed that the inclusion of active fillers could decrease the porosity of the green compacts effectively, increase ceramic yields of PCS by reacting with N 2, free carbon and/or gas volatile of PCS during pyrolysis to produce new compounds. It was found that Al and Cr could restrain the linear shrinkage of the green compact upon pyrolysis. While TiH 2 and Zr could not. The linear shrinkage got higher with increase of the volume ratio of TiH 2/PCS and Zr/PCS. It was also shown that the inclusion of Al and Zr could enhance the three point bending strength of the resulted ceramics with the strength of 212MPa and 104MPa when the volume ratio of Al/PCS and Zr/PCS were 60%vol, respectively, which were accordingly 3.3 and 1.6 times of that of the resulted ceramic in which active filler was not included. The inclusion of TiH 2 and Cr, however, could not enhance the strength. So Al was thought as the best among the four fillers. The phase compositions of pyrolysis products were analyzed using X ray diffraction(XRD). Fracture surfaces of specimens after three point bending tests were examined on the scanning electron microscope(SEM).