Chung Hsiu-Ying, Weinberger Michelle B, Levine Jonathan B, Cumberland Robert W, Kavner Abby, Yang Jenn-Ming, Tolbert Sarah H, Kaner Richard B
Department of Chemistry and Biochemistry and the California NanoSystems Institute, University of California, Los Angeles, CA 90095-1569, USA.
Science. 2007 Apr 20;316(5823):436-9. doi: 10.1126/science.1139322.
The quest to create superhard materials rarely strays from the use of high-pressure synthetic methods, which typically require gigapascals of applied pressure. We report that rhenium diboride (ReB2), synthesized in bulk quantities via arc-melting under ambient pressure, rivals materials produced with high-pressure methods. Microindentation measurements on ReB2 indicated an average hardness of 48 gigapascals under an applied load of 0.49 newton, and scratch marks left on a diamond surface confirmed its superhard nature. Its incompressibility along the c axis was equal in magnitude to the linear incompressibility of diamond. In situ high-pressure x-ray diffraction measurements yielded a bulk modulus of 360 gigapascals, and radial diffraction indicated that ReB2 is able to support a remarkably high differential stress. This combination of properties suggests that this material may find applications in cutting when the formation of carbides prevents the use of traditional materials such as diamond.
制造超硬材料的探索很少偏离高压合成方法的使用，这种方法通常需要吉帕斯卡的外加压力。我们报告称，通过常压电弧熔炼大量合成的二硼化铼（ReB2）可与用高压方法生产的材料相媲美。对ReB2的微压痕测量表明，在0.49牛顿的外加负载下，其平均硬度为48吉帕斯卡，在金刚石表面留下的划痕证实了其超硬性质。它沿c轴的不可压缩性在数值上与金刚石的线性不可压缩性相当。原位高压x射线衍射测量得出其体积模量为360吉帕斯卡，径向衍射表明ReB2能够承受非常高的差应力。这些特性的组合表明，当碳化物的形成阻碍使用诸如金刚石等传统材料时，这种材料可能在切割方面找到应用。
