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ISSN 2226-4108 CN 10-1154/TQ

Research Article

Residual stress variation in SiCf/SiC composite during heat treatment and its effects on mechanical behavior Xiaowu CHENa,b,*, Guofeng CHENGc, Junmin ZHANGa,b,d, Feiyu GUOa,b,d, Haijun ZHOUa,b, Chunjin LIAOa,b, Hongda WANGa,b, Xiangyu ZHANGa,b, Shaoming DONGa,b a

State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China b Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China c Analysis and Testing Center for Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China d School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, China Received: April 1, 2020; Revised: May 24, 2020; Accepted: June 8, 2020 © The Author(s) 2020.

Abstract: Residual stress originated from thermal expansion mismatch determines the mechanical properties of ceramic matrix composites (CMCs). Here, continuous SiC fiber reinforced SiC matrix (SiCf/SiC) composites were fabricated by nano-infiltration and transient eutectic-phase (NITE) method, and the residual stress of the composites was investigated using high-temperature Raman spectrometer. With temperature increasing from room temperature to 1400 ℃, the residual stresses of the matrix and the fiber decrease from 1.29 to 0.62 GPa and from 0.84 to 0.55 GPa in compression respectively, while that of the interphase decreases from 0.16 to 0.10 GPa in tension. The variation of residual stress shows little effect on the tensile strength of the composites, while causes a slight decrease in the tensile strain. The suppression of fiber/matrix debonding and fiber pulling-out caused by the residual stress reduction in the interphase is responsible for the decreasing tensile strain. This work can open up new alternatives for residual stress analysis in CMCs. Keywords: residual stress; nano-powder infiltration and transient eutectoid (NITE); Raman spectroscopy; mechanical properties

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Introduction

Ceramic matrix composites (CMCs), possessing excellent mechanical properties and corrosion resistance at high

* Corresponding author. E-mail: [email protected]

temperature, show great advantage over superalloys in aerospace applications. The advantage, however, may be compromised due to cracks pre-existed in the composites or induced by external service environment. The formation of cracks is dependent on various factors, of which residual stress plays an important role [1,2]. For CMCs materials, which are prepared and served in high temperature (> 1000 ℃ ) conditions, residual

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J Adv Ceram 2020, 9(4): 0–0

stress is inevitably formed due to the thermal expansion mismatch of the constituent phases. To maximize the vast benefits of CMCs, it is quite necessary to determinate and control the residual stress. There are several methods to measure residual str