Self-bonding mechanism of pure polycrystalline cubic boron nitride under high pressure and temperature. (January 2020)

• Record Type: Journal Article
• Authors: Deng, Wenli; Deng, Fuming; Hao, Cen; Yang, Xuefeng; Liu, Ruiping; Ma, Xiandong; He, Xuehua; Wang, Hao
• Is Part Of: International journal of refractory metals & hard materials. Volume 86(2020)
• Publication Date: 2020-01
• Subjects: Pure polycrystalline cubic boron nitride (PcBN) -- Grain size -- Bonding mechanism -- High pressure and high temperature (HP/HT); 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.2019.105061
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: Cubic boron nitride (cBN) powders with different grain size were used as a starting material, and the pure polycrystalline cubic boron nitride (PcBN) samples were sintered under the same conditions at 7GPa, 1700 °C, 270 s. Abrasion resistance and compressive strength of sintered pure PcBN samples were tested, and the microstructure was observed and analyzed by SEM, HRTEM, XRD and Raman spectrum. The results show that the particle size of cBN has not only a great influence on microstructure and property of the sintered pure PcBN un-der the same conditions but also influence on the bonding mechanism of the cBN particles. The inner stress of the pure PcBN sintered with the cBN particle size of 10 μm during the high pressure sintering process is about 199–222% higher than that of the sample with the cBN size of 1 μm. The wear ratio and the compressive strength of PcBN samples sintered with 10 μm cBN was increased by 47.7% and 39.7% than that of the sintered sample with 1 μm cBN respectively. The coarser-grained PcBN contains serious deformation and crushing, which can be attributed to the twin boundary and the stacking faults in the samples. As a consequence, the abrasion ratio and compressive strength of the pure PcBN are dramatically increased. It is assumed that self-bonding mechanism generated from plasticity deformation, which is a main bonding mechanism for the high pressure sintering of pure cubic boron nitride. Graphical abstract: Unlabelled Image Highlights: We synthesized pure PcBN with different cBN grain size. The pure PcBN with cBN grain size of 10 μm possesses excellent mechanical properties. The plastic deformation bonding mechanism was proposed for pure PcBN sintering. Strain hardening is the main reason to enhance the bonding strength of the pure PcBN.