The 50's of the last century middle period, scientists have syntheticdiamond and cubic boron nitride monocrystal. Since then, they have become widely used in industry of super hard materials, plays an irreplaceable role in modern processing. Super simply means Vivtorinox hardness greater than 40 GPa, while the sharp isVivtorinox hardness greater than 80 GPa. All the time, diamond is known as nature's most hard, hardness of 60 ~ 100 GPa cubic boron nitride; second, the hardness is 30 ~ 43 GPa. As the diamondantioxidant at low temperature ( about 600℃) and reaction withferrous materials, can only be used for processing ceramic material and aluminum, magnesium alloy. Cubic boron nitride oxidation at high temperature (about 1100℃) reaction and not with ferrous materials,so it is widely used in iron and steel materials processing industry.Unfortunately, the artificial synthesis of cubic boron nitride crystalhardness is less than half of diamond crystal, toughness is poor.Therefore, greatly improve the cubic boron nitride material hardness and toughness is the common pursuit of academic and industrial.

近十年来，田永君教授在国家杰出青年科学基金项目、重点项目、创新群体项目以及多项面上项目的持续资助下，致力于材料硬度的理论和实验研究。从化学键入手，2003年提出了共价晶体硬度的微观理论，解决了单晶硬度定量预测的理论难题。2012年，又将单晶硬度理论进行拓展，提出并建立了多晶材料硬度的理论模型。该模型预言：超细纳米结构可以使现有的硬材料变得超硬，使现有的超硬材料变得极硬。

In the recent ten years, Professor Tian Yongjun continued fundingprojects in the National Outstanding Youth Science Fund project, key projects, innovation projects and a number of groups on the surface,theoretical and experimental research devoted to the material hardness. Starting from the chemical bond, 2003 proposed amicroscopic theory of hardness of covalent crystals, solves theproblem of single crystal hardness quantitative prediction theory. In 2012, the hardness of single crystal, and the establishment of the proposed theoretical model of hardness of polycrystalline materials.The model predicted: ultrafine nano structures can be made of super hard hard materials available, so as to become extremely hard and super hard materials available. (Editor：admin)