As a major challenge for diamond cutting tool is very brittle. The diamond is a form of carbon atoms arranged very closely. In face centered cubic structure, each atom and the other four adjacent atoms connected by bonds, thus forming a very strong crystal structure. Not only the intensity is very high. This structure also makes the chemical properties of diamond is very stable, has very high thermal conductivity, low thermal expansion, the plane is very smooth, and a high refractive index. These properties are very useful. For example, surface smoothness and chemical inertness means non viscous. As a result of this, the wettability of diamond poor, can not work well with adhesive. When considering the diamonds for drilling tools,it becomes a problem.To do this, the only effective way is the particles in the metal matrix, relying on the mechanical strength of the metal, which is fixed. 

Heat is another problem, making it very easy to oxidation or reduction of graphite. Despite all that "diamonds are forever", but the fact is that when the temperature is above 400 DEG C, the diamond will quickly become soft graphite, graphite - especially in the presence of metal. In the end, although the lattice structure diamond anisotropy is very strong, but it does exist along the fracture surface, the crystal plane will smash.

The solution for the last question,is diamond, which is very much a small diamond crystal combination. Because of these small diamonds are very random, so it is not easy to form a continuous fracture surface, which makes the unfavorable fracture.

There are two types of diamond, diamond composite and thermodynamic stable diamond composite. The surface hardening tool, TSP type is obviously a better choice, but it is also facing new challenges. Especially the use of nickel coating to help sintering diamond matrix will lead to the many problems of nickel. Will form a weak chemical bond and diamond, when material expansion, the bond breaks. In addition, Ni also can promote diamond to graphite transformation.

By chemical vapor deposition method to form tungsten carbide coating on the surface of diamond crystal, tungsten carbide in the process from the condensed gas can be formed on the diamond surface atoms, which will form a strong bond, and does not have the formation porosity. The wettability of diamond coating has been greatly improved,the diamond can be better embedded cutting tool. Laboratory tests confirmed the fracture analysis. Tests show that even under the condition of fracture, the coating still bonding with diamond.

When the global search for oil and gas reserves to move to more remote areas, are more obvious. So the importance of drill engineering and manufacturing pressure is bigger. This new technology can get the world's most hard materials, plays an important role in many key aspects.

Posted by: hannahgwendolyn at 09:27 AM | No Comments | Add Comment
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