In-depth understanding of nano-twined cubic boron nitride materials
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In order to gain a deeper understanding of the birth, scientific significance, follow-up research direction and application prospects of the research results, on May 9, Yang Wei, director of the National Natural Science Foundation of China, came to Yanshan University for investigation.
According to reports, cubic boron nitride is an important superhard material and has been widely used in the iron-based material processing industry. Unfortunately, the synthetic cubic boron nitride single crystal is less than half the hardness of a diamond single crystal. The Hall-Petch relationship in materials science shows that the hardness of polycrystalline materials increases with decreasing grain size. Therefore, the synthesis of nanostructured cubic boron nitride has become an effective means to improve hardness.
Previously, using the graphite-structured boron nitride precursors for martensitic transformation at high temperatures and pressures, scientists have synthesized nanocrystalline cubic boron nitrides with a minimum grain size of 14 nanometers.
Tian Yongjun and his collaborators successfully synthesized a transparent nano-twisted cubic boron nitride using a special structure of onion boron nitride as a precursor. The average thickness of twins is only 3.8 nm, and its hardness reaches or exceeds artificial. The synthesized diamond single crystal has higher fracture toughness than commercial cemented carbide, and the oxidation resistance temperature is higher than that of the cubic boron nitride single crystal itself. These excellent comprehensive properties indicate that the nano twin structure cubic boron nitride is a long-awaited tool material in the industry. This research shows a new way to synthesize high-performance superhard materials -- to obtain ultra-fine nano twin structures.
At the symposium, Gao Ruiping, deputy director of the Fund Committee, first introduced the background and purpose of the survey. Liu Hongmin, president of Yanshan University, introduced the development of the school in recent years. Professor Tian Yongjun introduced his project in the National Outstanding Youth Science Fund, key projects, and innovative research. Under the continuous support of group projects and a number of projects, the company is devoted to the theoretical and experimental research experience of material hardness and the process of his team successfully synthesizing nano-crystal structure cubic boron nitride materials, and answered the questions of the researchers in detail. .
Yang Wei is very concerned about this research. He pointed out that high-performance super-hard and extremely hard materials have broad application prospects and extremely important research and development value. He congratulated the research team Tian Yongjun for his achievements and wished them greater success in the nano twin crystal diamond system. Yang Wei emphasized that as the main channel for state-funded basic research, the National Natural Science Foundation of China has been committed to supporting and encouraging Chinese scientists to make original work. He hopes that with the support of the Science Fund, more teams will get more and better research results.
Subsequently, Yang Wei and his party visited the State Key Laboratory of Metastable Materials Preparation Technology and Science of Yanshan University.