High-Pressure synthesis of Al2O3-cBN-hBN Self-lubricating ceramic. (May 2022)

• Record Type: Journal Article
• Authors: Wu, Jiakun; Wang, Haikuo.; Wang, Chao; Zhang, Zhicai; Tang, Yao; Hou, Zhiqiang; Wan, Shun; Wu, Dazhuan; Tan, Zhongjun; Ouyang, Xiaoping
• Is Part Of: Materials & design. Volume 217(2022)
• Publication Date: 2022-05
• Subjects: High pressure -- Al2O3 -- Cubic boron nitride -- Self-lubrication -- Wear mechanism; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2022.110638
• Languages: English
• ISSNs: 0264-1275

Abstract

Graphical abstract: Highlights: The high-pressure low temperature sintering method enables the synthesis of highly dense, fine-grained Al2 O3 -cBN-hBN self-lubricating ceramics with no cBN phase transformation, resulting in a Vickers hardness of up to 26.6 GPa, even higher than that of conventional ceramics. Reinforced phase cBN above 30 vol% tends to form a truss structure, resulting in less efficient pressure transfer during high pressure sintering, which affects the mechanical and thermal properties of the composite. The large modulus difference between cBN and lubricant facilitates the efficiency of lubricant release, reducing the lubricant content required to obtain excellent lubrication performance by half to 5 vol% and improving mechanical properties of composites. The wear of self-lubricating ceramics is more sensitive to the lubrication performance, just a 5 vol% increase in the lubricant may result in a lower wear rate than the self-lubricating ceramic with twice mechanical properties. Abstract: Al2 O3 -based self-lubricating ceramics are cutting tool materials that meet the extreme working conditions of dry cutting. However, due to the soft lubricating components, the mechanical properties of composites are dramatically reduced. In this paper, Al2 O3 -cBN-hBN self-lubricating material was designed. High density, fine grain ceramics were synthesized by high-pressure technology. The influence of thermodynamic condition, cBN/hBN addition on mechanical and thermal properties of sintered composites was analyzed. Friction and wear tests were carried out. It is found that the addition of cBN particles can significantly improve the mechanical and thermal properties of the composites. However, the truss effect caused by excessive volume fraction of cBN can reduce the pressure transfer efficiency, and then affect the properties of sintered composites. The different hBN content can change the wear mechanism of the composites. The release efficiency of hBN particles in composites was enhanced due to the large modulus difference between cBN and hBN. The well-sintered Al2 O3 -cBN-hBN bulks present an excellent mechanical property. The hardness of the composites is improved at least by 54% compared with the traditional self-lubricating material on the premise of ensuring fracture toughness and lubrication performance.