Abstract On December 25th, the 2013 “Top Ten Science and Technology Progress of Chinese Higher Education†awarding conference was held. Professor Tian Yongjun from the School of Materials Science and Engineering of Yanshan University presided over the successful completion of the scientific and technological achievements "Nano-twisted structure extremely hard cubic boron nitride". "China High...
On December 25th, the 2013 “Top Ten Science and Technology Progress of Chinese Higher Education†awarding conference was held. Professor Tian Yongjun from the School of Materials Science and Engineering of Yanshan University presided over the successful completion of the scientific and technological achievements "Nano-twisted structure extremely hard cubic boron nitride". The “Top Ten Scientific and Technological Progress of Chinese Higher Education Institutions†was selected by the Science and Technology Committee of the Ministry of Education and has been held for 16 sessions since its inception in 1998. This selection campaign has played a positive role in improving the overall level of science and technology in higher education institutions across the country and enhancing the technological innovation capabilities of higher education institutions, and has had a greater social impact.
The scientific and technological achievements of Yanshan University first established a theoretical model for the hardening of polycrystalline covalent materials, and found that the hardness at the nanometer scale should be derived from the joint contribution of the Hall-Page effect and the quantum confinement effect; The nanostructured cubic boron nitride was synthesized by the martensite transformation of the onion BN of crystal structure under high temperature and high pressure. The hardness of the material exceeds that of the artificial diamond single crystal, and the toughness is superior to that of the commercial hard alloy, and the oxidation resistance temperature is higher than that of the cubic boron nitride single crystal itself. At the same time, they also found that nano-twisted cubic boron nitride can continue to harden to 3.8 nm with the thickness of the twin crystal, breaking through the well-known lower limit of material hardening (about 10 nm). The basic principles and synthesis techniques of this research are equally applicable to the synthesis of nano twinned diamonds and their composite materials. From then on, a series of tool materials with better comprehensive performance will be born, and will be in the industries of machining, geological exploration, oil and gas mining, etc. Play an important role. The above research results were published in Nature magazine in January 2013.
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