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Introduction of strengthening and toughening mechanisms into intermetallic and ceramic matrix composites

将强化和增韧机制引入金属间化合物和陶瓷基复合材料中

基本信息

批准号：
11555175
负责人：
OCHIAI Shojiro
金额：
$ 8.45万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

Fiber-reniforced intermetallic and ceramic matrix composites are expected as the high temperature materials for next generation. The strength and toughness are, however, not sufficient for application. Further strengthening and toughening, and improvement of reliability are required for practical use. The aim of the present workwas to achieve high strength and toughness by introducing crack arrest mechanisms.Main results are summarized as follows.(1) Newmodelwas developed fordescriptionofmicro-damageaccumulationprocess and its influenceonoverall stress-straincurve, strengthand fracturemorphology. With thismethod, indications formaterial design to achieve high strength and toughness could be obtained.(2) Influences of residual stresses, sample size and loading condition on longitudinal cracking were clarified experimentally and theoretically, which supplied useful indications for toughening.(3) Influences of inter facial condition on unnotched and notched strengths were clarified experimentally, from which the necessary condition for crack-arrest was obtained.(4) In the Si-Ti-C-0/BMAS composite with heat-resistant crystallized glass matrix, the formation of carbon layer at interface was found to act to cause longitudinal cracking, which leads to blunting of the notch-tip. The critical energy release rate of longitudinal crackingwas first estimated to be around 100J/m2.(5) To aim toughening by inter facial control and introduction of ductile metal, C/C-Mg composite was prepared, which showed high Young's modulus, high strength and low notch-sensitivity.

纤维增强金属间化合物复合材料和陶瓷基复合材料有望成为下一代高温材料。然而，其强度和韧性不足以应用。在实际应用中，需要进一步强化和增韧，提高可靠性。本工作的目的是通过引入裂纹止裂机制来实现高强度和高韧性。主要研究结果总结如下。(1)建立了描述微损伤积累过程及其对整体应力-应变曲线、强度和裂缝形态影响的新模型。利用该方法，可以获得实现高强度和高韧性的材料设计指示。(2)从实验和理论上阐明了残余应力、试样尺寸和加载条件对纵向裂纹的影响，为增韧提供了有益的指导。(3)通过实验明确了界面条件对非缺口和缺口强度的影响，得出了裂纹止裂的必要条件。(4)在具有耐热结晶玻璃基体的Si-Ti-C-0/BMAS复合材料中，界面处碳层的形成导致了纵向开裂，导致缺口尖端钝化。初步估计纵向裂纹的临界能量释放率约为100J/m2。(5)以界面调控增韧和引入韧性金属为目标，制备了高杨氏模量、高强度、低缺口敏感性的C/C- mg复合材料。