热处理对C/SiC复合材料拉伸性能的影响
王红琴成来飞梅辉张立同
方鹏
（西北工业大学超高温结构复合材料国防科技重点实验室，西安710072）
文摘对等温化学气相渗透法（ICVI)制备的C/SiC复合材料进行热处理，利用声发射（AE）技术对热处理前后C/SiC试样拉伸过程声发射累积能量进行分析，通过SEM进行微结构观察。结果表明：界面层较薄的C/SiC试样经1500℃热处理后拉伸强度与初始强度相近，经1700和1900℃热处理后拉伸强度显著提高，其断裂应变随着热处理温度升高而大幅提高，弹性模量却呈现下降趋势；界面层较厚的C/SiC试样经1500和 1700℃热处理后拉伸强度变化不大，断裂应变显著提高，弹性模量逐渐降低，经1900℃热处理后拉伸强度和断裂应变开始下降，而弹性模量变化较小。热处理可以显著提高C/SiC的韧性，在拉伸过程中的断裂功和声发射累积能量均显著增加。界面层较薄的C/SiC断裂模式从脆性逐渐向韧性转变，而界面层较厚的C/SiC热处理后韧性进一步提高。
关键词C/SiC复合材料，热处理，拉伸性能，声发射
Effects ofHeatTreatment onTensilePropertiesof C/SiC Composite
Wang Hongqin
Cheng Laifei
Mei Hui
Zhang Litong
FangPeng
(National Key Laboratory of Thermostructure Composite Materials, Northwestem Polytechnical University, Xi'an710072)
AbstractC/SiC composites fabricated by isothermal chemical vapor infiltration were heat-treated. Acoustic emis-sion (AE) was introduced to analyze the variations of AE accumulative energy during monotonic tensile test. The micro-structures were examined by scanning electronic microscope ( SEM). The results indicate that, for the thin interlayer C/ SiC, its tensile strength is close to the initial one after heat treatment at 1 500 C, but tensile strengths of the composites can be increased after heat treatment at 1 700°C and 1 900°C. With the increase of heat treatment temperature, tensile stresses increase significantly and modulus decrease gradually. For the thick interlayer C/SiC, tensile strengths have lit-tle changes and tensile stresses increase obviously but modulus decrease gradually after heat treatment at 1 500°C and 1 700°C, while tensile strength and strain begin to decrease but modulus has litle change after the same heat treatment at 1 900°C. Heat treatment remarkably improves the toughness of C/SiC composites. The fracture work and AE accumula-tive energy increase obviously after heat treatment. For the composites with thin interlayer, the fracture mechanism va-ries from brittle mode to toughness one, and for the composites with thick interlayer, the toughness is further enhanced.
Key words C/SiC composite, Heat treatment, Tensile properties, Acoustic emission
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引言
C/SiC复合材料具有耐高温、高比强、高比模、低
密度和不发生灾难性损毁等优点，在航空发动机热端部件、航天飞机热防护系统和火箭发动机喷管等领域有广泛的应用前景1-2]，这些使用环境对复合材料的力学性能提出了较高的要求。
目前，为了提高陶瓷基复合材料力学性能，延长材料的使用寿命，国内外研究者在改善制备工艺方面
做了大量的T.作[3-6】，即对纤维、基体和界面进行改性，但是制备工艺研究过程周期较长，成本较高，因此需要寻找一种简单易行的工艺方法来改善复合材料力学性能。热处理工艺是金属材料改性最重要的工艺方法之一，近年来也开始应用于陶瓷基复合材料以提高材料的综合性能[7-81，目前对SiC陶瓷基复合材料热处理工艺的研究主要集中在SiC/SiC体系i9-101，而对C/SiC体系研究较少。本文利用ICVI
收稿月期：20090724；修间H期：20091204
基会项日：西北工业大学基础研究基金（NPU-FFR-JC200806）：国家自然科学基金国际合作项日（50820145202）作者简介；王红琴，1982年出生，硕士，主要从事C/SiC复合材料的研究。E-mail：w4365395@163.com
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万方数据
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