活性填料铬在聚碳硅烷裂解陶瓷中的应用

研究了活性填料铬 (Cr)在聚碳硅烷 (PCS)先驱体裂解陶瓷中的应用。研究表明 ,活性填料 Cr能有效降低陶瓷素坯的气孔率。 Cr可与 PCS气态裂解产物和 N2 气氛反应生成新的化合物 ,可明显提高 PCS的陶瓷产率。当 Cr/ PCS为 3 5% vol时 ,坯体的陶瓷产率为 1 0 0 %。在先驱体中引入 Cr能有效地抑制坯体在裂解过程中的收缩。Cr含量越高 ,素坯裂解后的收缩越小。当 Cr/PCS为 4 6% vol时 ,素坯在裂解前后线收缩率为 0 ;由于生成产物的体积效应较大 ,以及与 Si C热膨胀系数的不匹配性 ,导致陶瓷烧成体强度有所下降。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 Chromium in the Preparation of Polycarbosilane Derived Ceramics

The application of chromium(Cr) in the preparation of polycarbosilane(PCS) derived ceramics was investigated. The results showed that Cr could decrease the porosity of the green compact, increase ceramic yield of PCS by reacting with N_2 to produce nitride and gas volatile of PCS during pyrolysis to produce carbide, the ceramic yield would be 100% while the volume ratio of Cr/PCS was 35%vol, and restrain the linear shrinkage of the green compact upon pyrolysis, the linear shrinkage decrease with increasing the volume ratio of Cr/PCS, the linear shrinkage would be zero when the volume ratio of Cr/PCS was 46%vol. However, Cr couldn't enhance the threepoint bending strength of the resulted ceramic for the cracks from volume expansion and coefficient of thermal expansion mismatch. The phase compositions of pyrolysis products were analyzed using Xray diffraction(XRD). Fracture surfaces of specimens after threepoint bending tests were examined on the scanning electron microscope(SEM).