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According to the website of on April 20, 2007, the use of super-hard materials is very extensive. Whether it is drill bits for drilling oil and road repairing, or anti-friction coatings for precision instruments and watches, it is necessary to use super. Hard material. UCLA scientists have developed a new way to make superhard materials that are made of superhard materials that are extremely resistant to abrasion and cracking. Their findings have been published in the April 20 issue of Science Journal.
The study's co-author, Chad B. Kane, is a professor of inorganic chemistry, materials science and engineering at the University of California, Los Angeles. He believes that diamond is the hardest material in the world because of the extremely short covalent bond between the carbon atoms of diamond. In fact, most of the diamonds used in the world are synthetic and very expensive. Diamond powder is not used in the manufacture of oil drill bits, road construction machines and digger for digging holes. However, diamond cannot be used to cut steel because cutting steel will destroy the diamond blade. Kane said that cubic boron nitride is a substitute for diamond and can be used to cut steel, but it is synthesized under very high temperature and pressure conditions and is more expensive than diamond.
Superhard materials have "super incompressibility", meaning that they are resistant to changes in shape, which is a necessary condition for hardness. There are two ways to make superhard materials: one is to imitation of diamond by using carbon and synthesizing it with boron or nitrogen to maintain a shorter covalent bond; the other is to find "incompressibility." "The metal is trying to make it hard." Kane and his colleagues are developing the second method. Kane said: "Our vision is to synthesize an 'incompressible' metal that happens to be low-hard, but it has short covalent bonds that can harden it." Kane is a UCLA school. Member of the California Institute of Nanosystems, which encourages interdisciplinary collaboration to address issues related to nanoscience and nanotechnology.
Tantalum is a relatively soft metal element and is the most "incompressible" metal known to date. In 2005, Kane's research team synthesized a cesium element with a short covalent bond atom to create a metal. Almost as "incompressible" material as diamond. It is so hard that it can even mark on sapphire with a hardness of 9 (hardness is 1-10). "We found that if we combine boron and niobium, we can only increase the separation distance of niobium atoms in niobium by 10%. This is very good; if you want to reduce the separation distance between atoms as much as possible, "We need to find better transition metals," Kane said. "So we carefully searched all the transition metals to see if there was a better transition metal than 锇, so that the expansion coefficient was less than 10%. We found that only 铼 has this Potential, therefore, we make bismuth diboride."
Tantalum is a high-density, low-hardness metal that is placed just behind the tantalum element in the periodic table. "We have synthesized a short covalent bond. We can only increase the separation distance of germanium atoms in the base metal by 5%, so that it is both 'incompressible' and very hard. The distance between the germanium atoms in the base metal. Only 5% expansion - this is the key to this scientific paper. In one direction, the 'incompressibility' of tantalum diboride is the same as that of diamond, and in the other direction, the 'compressibility of barium diboride The property 'is only slightly higher than the diamond." At low forces, the hardness of the lanthanum diboride is equal to that of the cubic structure of boron nitride, which is the second hard material. At higher forces, the hardness of lanthanum diboride is only slightly lower than that of boron nitride. Kane said: "Our materials are very hard enough to scratch diamonds, much harder than bismuth diboride."
Moreover, other superhard materials, including diamond and cubic boron nitride, are produced under expensive high pressure conditions. Kane said, "Our materials can only be manufactured through a simple process, without the need for pressure." When talking about cooperation, Kane said, "The reason why I came to UCLA, the reason why I like this place because no matter what you do, for example, personally, whenever you want to make a new material, you often need equipment and skills that you don't have. UCLA has materials. Experts in the manufacturing field and the corresponding equipment, every time I have questions, everyone is willing to help me experiment and actively cooperate with me.†Kane believes that although the new superhard materials have great potential, they are not yet It is possible to replace diamond in a short time.
Hard as diamond new material manufactured under normal pressure
Researchers have been able to create a superhard material that can scratch a diamond under ambient pressure.