The Fabrication and Mechanical Properties of Laminated ZrB2-Mo5SiB2 Ceramics with an Mo-Mo5SiB2 Interlayer

Yanfang Wang,Mingliang Li,Hongliang Xu,Hongxia Lu,Hailong Wang,Jinpeng Zhu,Gang Shao,Rui Zhang,Bingbing Fan,Hailiang Wang,Wen Liu

doi:10.3390/met11122018

Abstract

The excellent physical and chemical properties of ultra-high temperature ceramics make them suitable for many high-temperature structural components, while their poor toughness and high sintering temperature become key limitations to their application. Laminated toughening has long been considered an effective toughening method to improve the mechanical properties of ceramics. In this study, laminated ZrB2-Mo5SiB2 ceramics with an Mo-Mo5SiB2 interlayer were fabricated by tape casting and hot press sintering at 1900 °C for 2 h. Different layer thickness ratios between the matrix layer and the interlayer were designed to illustrate the toughening mechanism. Both the fracture toughness and flexural strength of the laminated ceramics showed a trend of first increasing and then decreasing with the increase of the layer thickness ratio. High fracture toughness (9.89 ± 0.26 MPa·m1/2) and flexural strength (431.6 ± 15.1 MPa) were obtained when the layer thickness ratio was 13. The improvement in fracture toughness of the laminated ceramics could be attributed to the generation of the residual stress, the deflection and the bifurcation of the cracks. Residual stress that developed in the laminated ceramics was also evaluated.

Highlights

Zirconium diboride (ZrB2), one of the most promising ultra-high temperature ceramic (UHTC) materials, presents an excellent combination of physicochemical properties, such as an ultra-high melting point (3245 ◦C), high hardness and stiffness, a relatively low thermal expansion coefficient and density, and excellent chemical and physical stability at high temperatures [1,2,3,4,5]
Polyethylene glycol (PEG), Polyvinyl butyral (PVB), and Tricresyl phosphate (TCP) provided by Shanghai Macklin Biochemical Co. were chosen as the dispersant, binder, and plasticizer, respectively
In order to improve the fracture toughness of ZrB2-based ceramics, laminated ZrB2-Mo5SiB2 ceramics with Mo-Mo5SiB2 interlayer were designed based on the “brick-and-mortar” of the nacre

Summary

Introduction

Zirconium diboride (ZrB2), one of the most promising ultra-high temperature ceramic (UHTC) materials, presents an excellent combination of physicochemical properties, such as an ultra-high melting point (3245 ◦C), high hardness and stiffness, a relatively low thermal expansion coefficient and density, and excellent chemical and physical stability at high temperatures [1,2,3,4,5]. These properties make the material capable of many high-temperature structural applications, including use for hypersonic vehicles, high-temperature shielding, and thermal protection systems [6,7,8,9]. The stress acts at the crack tip to arrest crack propagation, achieving the strengthening and toughening of the materials

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