Microstructural regulation, oxidation resistance, and mechanical properties of Cf/SiC/SiHfBOC composites prepared by chemical vapor infiltration with precursor infiltration pyrolysis

Yang Lyu,Wenbo Han,Yuan Cheng,Guiqing Chen,Baihe Du,Qingrong Lv,Guangdong Zhao,Xinghong Zhang,Shanbao Zhou

doi:10.1007/s40145-021-0521-y

Abstract

To further improve the oxidation resistance of polymer derived ceramic (PDC) composites in harsh environments, Cf/SiC/SiHfBOC composites were prepared by chemical vapor infiltration (CVI) and precursor impregnation pyrolysis (PIP) methods. The weight retention change, mechanical properties, and microstructure of Cf/SiC/SiHfBOC before and after oxidation in air were studied in details. Microscopic analyses showed that only the interface between the ceramics and fibers was oxidized to some extent, and hafnium had been enriched on the composite surface after oxidizing at different temperature. The main oxidation products of Cf/SiC/SiHfBOC composites were HfO2 and HfSiO4 after oxidation at 1500 °C for 60 min. Moreover, the weight retention ratio and compressive strength of the Cf/SiC/SiHfBOC composites are 83.97% and 23.88±3.11 MPa, respectively. It indicates that the Cf/SiC/SiHfBOC composites should be promising to be used for a short time in the oxidation environment at 1500 °C.

Highlights

The requirements of thermal protection materials such as lightweight, strengthening toughening, and oxidation resistance are increasing in the combustion chamber and tail nozzle of aerospace vehicles [1,2,3]
In addition to the amorphous diffraction peaks of C, the diffraction peaks of SiC at 35.6°, 60.1°, and 71.9° were found in the X-ray diffractometer (XRD) patterns of Cf/SiC samples [23,25,26], which further indicated the existence of SiC coating
The results show that a large amount of CO2, CO, B2O3, and other gases escape during the oxidation process of Cf/SiC/SiHfBOC-7 composites, and many pores are formed on the surface of the samples

Summary

Introduction

The requirements of thermal protection materials such as lightweight, strengthening toughening, and oxidation resistance are increasing in the combustion chamber and tail nozzle of aerospace vehicles [1,2,3]. Continuous carbon fiber (or carbon fiber perform) reinforced ceramic matrix composites have the excellent properties, such as low density [15], high toughness [16], high strength, and high reusability [17], especially the toughening property [18], which help to solve the inherent brittleness of ceramic materials [19]. It improves the thermal shock resistance of ceramic materials, and maintains the inherent high-temperature stability and low thermal expansion coefficient of ceramic materials [8]. Cf/SiC/SiHfBOC composites were prepared with lower PIP cycle times, and have excellent oxidation resistance and mechanical property

Experimental

Results and discussion

Conclusions