Application and Prospect of diamond and ultra hard materials (1)
2015/9/3 13:45:38
1 Overview
Since 1955, the United States GE company to use high temperature and high pressure method to obtain artificial diamond, has aroused the concern of the whole world, especially the lack of natural diamond deposits in the country has a huge attraction. The cubic boron nitride was synthesized by high temperature and high pressure in 1957. (CBN). These man-made materials have greatly enriched the treasure house of materials, especially for the development of cutting tools. At that time, the main purpose of these materials in the field of mechanical processing is to make abrasive. After 20 years of efforts, in 1977 GE successfully developed a diamond sintered body (PCD) and CBN (PCBN) sintered body, and made into a blade, so that the use of artificial super hard materials to further expand, from grinding to the cutting.
Even more gratifying is the synthesis of large particles of single crystal diamond and single crystal CBN, which creates the conditions for the substitution of natural diamond. According to the data show that the current synthetic single crystal diamond, the largest actually weighing 34.2 carat, but the practical application is still to be further research, exploration, and now the cost is also expensive.
Our country in the development of artificial diamond is also very rapid, according to statistics, in 1993 the world's output is 900000000 carat, and our country has reached 230000000 ~ 2.1 carat, ranking first in the world. This shows that our country in the field of considerable potential. The development of this technology to promote the application of the ultra hard material in our country has created the premise.
Chemical vapor deposition (CVD) and physical vapor deposition (PVD) technology is a breakthrough in the development of cutting tools is a revolution, first coated with a variety of ceramic materials, and now developed to the type of diamond film, diamond film, and CBN film coating. This development has virtually increased the surface hardness of all cutting tools. Now the technology of vapor deposition is still in development. As far as the diamond is concerned, it has expanded from thin film to thick film, and its deposition rate is from the average per hour to the maximum hourly 0.93mm.
Today science and technology in the rapid development, the emergence of a large number of new materials, which quite a part is high alloy steel, high silicon aluminum alloy, high strength composite materials, and these are difficult to cut materials, such as the aerospace industry commonly used Inconel718 nickel base alloy is one example. Due to the development of ultra hard materials, it has greatly eased the difficult situation of these materials.
At present, the industrial developed countries have applied these new materials to the manufacturing industry rapidly, and thus improve the productivity, especially in Europe and the United States and japan. Although China has made considerable progress in this field, there is a considerable gap in the improvement and application of the. In the face of the challenge of twenty-first Century, the super hard materials such as diamond, artificial CBN will play a huge role, people can wait and see.
2 characteristics and effects of diamond and ultra hard materials
Natural single crystal diamond is the world's most hard substances, so as abrasive and cutting tools, its performance is unparalleled, with diamond tool as an example, the cutting edge radius can be grinding to even scanning electron microscopy, SEM, can not be detected, until now there is no a material to replace and use it to machining, often can directly get the mirror, the widely application in instrument, electronics, optics and other fields, become an indispensable cutting tool material, but because the cost is expensive, grinding superb skills, so has hampered its widespread application.
Super hard materials, due to its excellent performance, have been used to expand the application of the traditional processing, such as optical glass processing, stone processing, processing, hard brittle materials and so on.
Natural diamond, due to anisotropy, so the crystal surface hardness are very large, in the grinding, choose the soft side as the grinding surface, and the hard surface as the rake face and flank, which brings favorable conditions for grinding, because of its anisotropy, and so on in use, consideration must be given to the reasonable choice, such as crystal face, anvil hardness, in use, by pressing or jumping to measure the detected material hardness, but due to the different working surface hardness, results are also different, of course, hard surface, beneficial to prolonging the life, such as natural and die diamond manufacturing, due to a hole in the surface by the crystal surface, so the hardness is not the same, will not wear uniform, will also give the circular wire caused by stress difference, the hardness is not uniform, but the impact of the use, sintered diamond and diamond thick film, due to isotropic, in this type of product use becomes very good.
PCD, PCBN, because of their different grain, different concentration, the performance is different, must be a reasonable choice. Thick film diamond is pure diamond, its hardness is close to the natural diamond, and PCD, PCDN is the diamond powder and binder mixed together, so the hardness is influenced by the binder, its hardness is not as good as the former.
As we all know, the diamond and iron have affinity, can only be used in non-ferrous metals and non-metallic materials, and CBN even at high temperature of 1000 degrees, cutting black metal can also be fully qualified. Has become the future of the main cutting tool material. General super hard material refers to the man-made diamond, artificial CBN. The existence of these two materials, played a complementary role, can cover the current and future development of a variety of new materials for the processing, the whole cutting process is very favorable.
High precision cutting tools of the diamond cutting tool requires a superb skill, in order to obtain a higher accuracy of the cutting edge radius, especially less than 0.05um