Fabrication of (SiC-AlN)/ZrB2 Composite with Nano-Micron Hybrid Microstructure via PCS-Derived Ceramics Route.

Aidong Xia,Jie Yin,Wei Liu,Zhengren Huang,Xuejian Liu,Xiao Chen

doi:10.3390/ma14020334

Abstract

In this work, a (SiC-AlN)/ZrB2 composite with outstanding mechanical properties was prepared by using polymer-derived ceramics (PDCs) and hot-pressing technique. Flexural strength reached up to 460 ± 41 MPa, while AlN and ZrB2 contents were 10 wt%, and 15 wt%, respectively, under a hot-pressing temperature of 2000 °C. XRD pattern-evidenced SiC generated by pyrolysis of polycarbosilane (PCS) was mainly composed by 2H-SiC and 4H-SiC, both belonging to α-SiC. Micron-level ZrB2 secondary phase was observed inside the (SiC-AlN)/ZrB2 composite, while the mean grain size (MGS) of SiC-AlN matrix was approximately 97 nm. This unique nano-micron hybrid microstructure enhanced the mechanical properties. The present investigation provided a feasible tactic for strengthening ceramics from PDCs raw materials.

Highlights

With a representative feature of strong covalent bonding, SiC possesses high strength, hardness, and chemical stability, as well as excellent thermal shock and wear resistance
There are two general methods to improve the mechanical properties of Polymer-derived ceramics (PDCs)
Raw PCS used in our study was in liquid state

Summary

Introduction

With a representative feature of strong covalent bonding, SiC possesses high strength, hardness, and chemical stability, as well as excellent thermal shock and wear resistance. PDCs are mainly composed of a network by free carbon and Si-rich nanodomains inside [9], while grains of PDCs are usually nanosized This unique microstructure renders excellent physical and chemical properties in PDCs [10,11], such as thermal [12,13,14,15], electrical [16,17,18], electrochemical energy storage [19,20], and electromagnetic properties [21,22,23,24,25]. During the pyrolysis of the ceramic precursors, a large amount of small molecule gas would be released, and the green body would shrink, with the formation of pores and cracks Defects, such as pores and cracks, could deteriorate the mechanical properties of PDCs, limiting the application of PDCs [5].

Methods

Results

Conclusion