• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >A thermodynamic and kinetic study of the deposition of silicon carbide from various precursor systems with application to the preparation of lamellar-matrix/continuous fiber-reinforced composites.
【24h】

A thermodynamic and kinetic study of the deposition of silicon carbide from various precursor systems with application to the preparation of lamellar-matrix/continuous fiber-reinforced composites.

机译：从各种前驱体系统沉积碳化硅的热力学和动力学研究，用于制备层状基体/连续纤维增强复合材料。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Chemical vapor infiltration (CVI) was investigated as a processing technique for preparation of composites composed of Nicalon{dollar}sp{lcub}rm TM{rcub}{dollar} fibers and alternating layers of SiC/C/SiC... in a lamella-form matrix. A state-of-the-art CVD (chemical vapor deposition) facility was designed and constructed to support this effort. Carbon layers were deposited from propylene/argon gas mixtures. Two precursor systems were investigated as routes to the SiC layers: (1) HSiCl{dollar}sb3{dollar} + hydrocarbon (i.e., {dollar}rm CHsb4, Csb2Hsb2, Csb3Hsb6) + Hsb2{dollar}, and (2) {dollar}rm CHsb3SiClsb3 + Hsb2{dollar}. Thermodynamic evaluations were performed to get an understanding of which deposit phases would be stable under a variety of operating conditions. These predictions were compared to experimental results.; In the first SiC system, deposition of single-phase SiC was dependent on the deposition temperature and hydrocarbon species. Silicon was the primary phase to deposit when trichlorosilane was mixed with methane, whereas carbon co-deposited with {dollar}beta{dollar}-SiC when {dollar}rm Csb2Hsb2{dollar} was used as the carbon source gas. Pure {dollar}beta{dollar}-SiC, as determined by X-ray diffraction, was deposited over the 1000-1200{dollar}spcirc{dollar}C temperature range for the {dollar}rm HSiClsb3 + Csb3Hsb6 + Hsb2{dollar} system. An apparent activation energy of 10 kJ/mole for deposition of {dollar}beta{dollar}-SiC over this temperature range indicates a diffusion-controlled growth regime.; In the second system, single phase {dollar}beta{dollar}-SiC was prepared over a wide range of conditions including: (1) temperature = 1123-1723K, (2) pressure = 266-1329 kPa, and (3) {dollar}rm Hsb2{lcub}:{rcub}CHsb3SiClsb3{dollar} = 8:1-30:1. Morphologies ranging from smooth at low temperatures to highly faceted at high temperatures were observed. Kinetic analysis over the temperature range 850-1450{dollar}spcirc{dollar}C indicated a transition from surface reaction-controlled (E{dollar}sb{lcub}rm A{rcub}{dollar} = 130 kJ/mole) to diffusion-controlled (E{dollar}sb{lcub}rm A{rcub}{dollar} = 13 kJ/mole) at {dollar}{lcub}sim{rcub}1200spcirc{dollar}C. Decreasing pressure and temperature were found to promote the surface reaction-controlled regime. Densification of fibrous preforms improved with decreasing temperature and pressure as expected from the kinetic studies.; Results obtained from the thermodynamic and kinetic investigations were applied to the preparation of lamellar matrix composites. Lamellar matrix/continuous fiber reinforced ceramic matrix composites were successfully prepared using chemical vapor infiltration. Fabricated composites were tensile tested to investigate the effect of the lamellar structure on mechanical properties.
机译：研究了化学气相渗透（CVI）作为制备复合材料的工艺，该复合材料由Nicalon {dollar} sp {lcub} rm TM {rcub} {dollar}纤维和SiC / C / SiC ...的交替层组成形式的矩阵。为了支持这项工作，我们设计并建造了最先进的CVD（化学气相沉积）设备。从丙烯/氩气混合物中沉积碳层。研究了两种前驱体系统作为通往SiC层的途径：（1）HSiCl {美元} sb3 {美元} +碳氢化合物（即，{rm} rm CHsb4，Csb2Hsb2，Csb3Hsb6）+ Hsb2 {美元}，和（2）{美元} rm CHsb3SiClsb3 + Hsb2 {美元}。进行了热力学评估，以了解在各种操作条件下哪些沉积相将是稳定的。这些预测与实验结果进行了比较。在第一个SiC系统中，单相SiC的沉积取决于沉积温度和碳氢化合物种类。当三氯硅烷与甲烷混合时，硅是沉积的主要相，而当将{rm} Csb2Hsb2 {dol}用作碳源气体时，碳与{beta} {dollar} -SiC共沉积。通过X射线衍射测定，在rmrm HSiClsb3 + Csb3Hsb6 + Hsb2 {dollar}的1000-1200 {spcirc {dollar} C温度范围内沉积了纯的{dollar} beta {dollar} -SiC。系统。在该温度范围内用于沉积{dollar}β{dollar} -SiC的表观活化能为10kJ / mol，表明扩散受控的生长方式。在第二个系统中，在很宽的条件范围内制备了单相{dollar}β{dollar} -SiC，包括：（1）温度= 1123-1723K，（2）压力= 266-1329 kPa，以及（3）{美元} rm Hsb2 {lcub}：{rcub} CHsb3SiClsb3 {dollar} = 8：1-30：1。观察到形态从低温光滑到高温多面。在850-1450温度范围内的动力学分析表明，从受控的表面反应（E {dollar} sb {lcub} rm A {rcub} {dollar} = 130 kJ / mol）过渡到扩散在（dollar）{lcub} sim {rcub} 1200spcirc {dollar} C下控制（E {dollar} sb {lcub} rm A {rcub} {dollar = 13 kJ / mole）。发现降低压力和温度可促进表面反应受控状态。如动力学研究所预期的，随着温度和压力的降低，纤维预型件的致密化得到改善。从热力学和动力学研究获得的结果可用于制备层状基质复合材料。使用化学气相渗透法成功制备了层状基体/连续纤维增强的陶瓷基体复合材料。对复合材料进行拉伸测试，以研究层状结构对机械性能的影响。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号