Microstructural and mechanical properties of cBN-Si composites prepared from the high pressure infiltration method

• Published in: International journal of refractory metals & hard materials Vol. 61; pp. 1 - 5
• Main Authors: Liu, Yinjuan, He, Duanwei, Wang, Pei, Yan, Xiaozhi, Xu, Chao, Liu, Fangming, Liu, Jin, Hu, Qiwei
• Format: Journal Article
• Language: English
• Published: Shrewsbury Elsevier Ltd 01.12.2016; Elsevier BV
• Subjects: cBN; Compacts; Composite materials; Deformation; Fracture mechanics; Fracture toughness; Grain size; High pressure; Indentation; Infiltration; Infiltration sintering; Mechanical properties; Microstructure; Oxidation; Polished; Refractory metals; Silicon; Studies; Thermal stability; Grain size; Silicon; Infiltration sintering; cBN; High pressure
• ISSN: 0263-4368; 2213-3917
• DOI: 10.1016/j.ijrmhm.2016.07.020

The grain size dependence of the mechanical properties of cBN-Si composites prepared using the high pressure infiltration method has been investigated. Indentation testing indicates that cBN-Si composites have hardness values of 38–43GPa, which increase with increasing grain size and are harder than traditional polycrystalline cBN composites (PcBNs). Thermostability analyses display that cBN-Si composites with a grain size of >9μm also possess a higher temperature of oxidation, compared to traditional PcBNs, and the thermostability increases with increasing cBN grain size. Fracture toughness tests show that almost no cracks appear on the polished cBN-Si samples when the loading forces are increased to 294N and the fracture toughness is better than for commercial samples. Scanning electron microscopy illustrates that deformations and close pores occurred easily between coarse BN grains, leading to denser cBN-Si compacts with better mechanical performances. •Systematically studying the grain size dependence of mechanical properties and microstructure of cBN-Si composites.•The cBN-Si compacts are more denser and have better mechanical performances.•The uniformity of the overall performance of cBN-Si composites.•The cBN-cBN bonds appeared extensively in the sintered samples.•The deformation occurred more easily for the coarse grain cBN than the fine-grained cBN at high pressure and temperature.