Effects of Pore on Thermal Diffusivity and Thermal Radiation Properties of C/SiC Composites at High Temperatures
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Effects of Pore on Thermal Diffusivity and Thermal Radiation Properties of C/SiC Composites at High Temperatures Fuyuan Wang 1,2
3
& Laifei Cheng & Shuhua Liang
1,2
Received: 14 May 2019 / Accepted: 20 September 2019/ # Springer Nature B.V. 2019
Abstract
The effects of pore in C/SiC composites on thermal diffusivity and thermal radiation properties were investigated systematically. Pores were introduced into C/SiC by oxidizing carbon phase at 700 °C and damaged the thermal properties of C/SiC composites. Because of little changes in the pore shape and the pore orientation in C/SiC, thermal diffusivity of samples increased linearly with porosity. The pores within C/SiC absorbed and reflected the radiated heat, decreasing spectral emissivity. However, the temperature dependence of spectral emissivity didn’t change by the pore. With measurement temperature increasing, the pores weakened the thermal radiation property of samples gradually. A linear relation was suggested to quantify the negative effect of pores on the total emissivity. Keywords C/SiC . Pore . Thermal diffusivity . Thermal radiation
1 Introduction Carbon fiber-reinforced silicon carbide (C/SiC) composites havebeen widely used in aeronautical and astronautical applications due to their excellent thermal, physical, and mechanical properties at high temperatures compared to conventional materials [1–3]. Servicing as thermostructural components at high temperatures, such as in wing leading edges and nozzle ramps, C/SiC composites are frequently subjected to high levels of transient or steady-state heat flow and/or thermal shock [4, 5]. The responses of C/SiC composites to these thermal conditions are related to * Fuyuan Wang [email protected]
1
School of Materials Science and Engineering, Xi’an University of Technology, Xi’an, Shaanxi 710048, People’s Republic of China
2
Shaanxi Province Key Laboratory for Electrical Materials and Infiltration Technology, Xi’an University of Technology, Xi’an, Shaanxi 710048, People’s Republic of China
3
Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi’an, Shaanxi 710072, People’s Republic of China
Applied Composite Materials
the relevant thermophysical properties. For materials such as the hot part of thermal protection systems, thermal conduction and thermal radiation are the principal agents of heat transfer [6]. Thermal diffusivity is used to describe the heat transfer in the material’s interior, while infrared emissivity is a key parameter for evaluating heat dissipation between materials and the environment. Both parameters are intensively affected by the microstructure and constituents of C/SiC composites. Moreover, the servicing environment usually contains corrosive mediums, such as O2 andH2O,which corrodes andchanges themicrostructure andconstituentsof C/SiC composites [7, 8]. The microstructure evolution of C/SiC during service, such as the oxidation of carbon and matrix, increasing porosity, inevitably affects the thermal prop
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