Microstructural evolution and performance of carbon fiber-toughened ZrB2 ceramics with SiC or ZrSi2 additive

Kaixuan Gui,Gang Wang,Ping Hu,Fangyu Liu,Zhongjia Huang

doi:10.1007/s40145-018-0284-2

Abstract

ZrB2–SiC/ZrSi2 ceramics containing 30 vol% carbon fiber (Cf) additive were fabricated by hot pressing at low temperature (1500 °C) using submicron ZrB2 powders, and their microstructural evolution and performance were investigated. The addition of SiC or ZrSi2 significantly reduced the onset sintering temperature and enhanced the densification of ZrB2. ZrB2–ZrSi2–Cf showed poor performance owing to the serious fiber degradation, while the fiber degradation was effectively inhibited in ZrB2–SiC–Cf resulting in high fracture toughness, substantial fiber pull-out, and non-brittle fracture mode for such material. The critical thermal shock temperature difference of ZrB2–SiC–Cf was up to 741 °C, significantly higher than those of ZrB2–SiC/ZrSi2 and ZrB2–ZrSi2–Cf. Moreover, this composite displayed a good oxidation resistance at 1500 °C in air.

Highlights

Zirconium diboride (ZrB2) is one of a family of transition metal boride compounds that belong to a class of materials known as ultra-high temperature ceramics (UHTCs)
Typical SEM images of the starting ZrB2 powders and the mixed ZrB2–silicon carbide (SiC)–carbon fiber (Cf) powders are shown in Fig. 1 www.springer.com/journal/40145
ZrB2, ZrB2–SiC, and ZrB2–ZrSi2 ceramics with submicron ZrB2 powders, typical densification curves of these materials by hot pressing at 1500 °C for 1 h are presented in Fig. 2

Summary

Introduction

Zirconium diboride (ZrB2) is one of a family of transition metal boride compounds that belong to a class of materials known as ultra-high temperature ceramics (UHTCs). Researches reveal that zirconium disilicide (ZrSi2) can facilitate full densification of ZrB2 at low temperatures by particle deformation and formation of a grain-boundary amorphous film during hot pressing [14,15]. Another effective way to reduce the sintering temperature of ZrB2 is to use nanosized powders as starting material instead of microsized powders since the sintering activity of nanosized particles is dramatically higher than that of their microsized counterparts [16,17,18]

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Conclusion