High-pressure synthesis of Al2O3-cBN composites: Effect of thermodynamic condition and cBN volume fraction on their microstructure and properties. (December 2022)

• Record Type: Journal Article
• Authors: Wu, Jiakun; Wang, Haikuo; Zhang, Zhicai; Hou, Zhiqiang; Wu, Dazhuan; Ouyang, Xiaoping
• Is Part Of: International journal of refractory metals & hard materials. Volume 109(2022)
• Publication Date: 2022-12
• Subjects: High pressure -- Al2O3 -- Cubic boron nitride -- Mechanical properties; Heat resistant alloys -- Periodicals; Refractory materials -- Periodicals; Metallography -- Periodicals; Alliages réfractaires -- Périodiques; Matériaux réfractaires -- Périodiques; Métallographie -- Périodiques; Heat resistant alloys; Metallography; Refractory materials; Periodicals; Electronic journals; 669.73
• DOI: 10.1016/j.ijrmhm.2022.105969
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: Alumina with different amounts of Cubic boron nitride (cBN) was synthesized by a high-pressure sintering method. By adjusting the sintering temperature to a relatively low level, the undesirable reverse transformation from cBN to hBN was avoided, and almost entirely dense composites were obtained. The sintering behaviors, phase compositions, microstructures, and mechanical properties of Al2 O3 -cBN composites were investigated. The cBN phase significantly improved the modulus of elasticity and hardness, but the fracture toughness was only slightly increased. Vickers hardness of Al2 O3 –40 vol% cBN composites sintered at 850 °C showed a maximum value of 30 GPa. The Al2 O3 –30 vol% cBN composite sintered at 1250 °C had the highest fracture toughness of 5.7 MPa·m 1/2 . Highlights: The Vickers hardness, fracture toughness of Al2 O3 -cBN synthesized by high-pressure sintering reached 30 GPa and 5.7 MPa·m 1/2 . It is proposed to sinter Al2 O3 -cBN at high pressure and low temperature to ensure high density and no cBN phase transition. The effects of sintering parameters and cBN content on the properties of the Al2 O3 -cBNare revealed for the first time.