1. The concept of diamond surface coating
Diamond surface coating, refers to the use of surface treatment technology on the diamond surface coated with a layer of other materials film. As a coating material, usually metal (including alloy), such as copper, nickel, titanium, molybdenum, copper tin titanium alloy, nickel cobalt alloy, nickel cobalt phosphorus alloy, etc.; coating material also some non-metallic materials, such as ceramics, titanium carbide, titanium ammonia and other compounds refractory hard materials. When the coating material is metal, it can also be called diamond surface metalation.
The purpose of surface coating is to endow diamond particles with special physical and chemical properties, so as to improve their use effect. For example, the use of surface-coated diamond abrasive manufacturing resin grinding wheel, its service life is greatly extended.
2. Classification of the surface coating method
Industrial surface treatment method classification see the figure below, which has been actually applied in super hard abrasive surface coating method, more popular is mainly wet chemical plating (no electrolysis plating) and plating, dry plating (also known as vacuum plating) in chemical vapor deposition (CVD) and physical vapor deposition (PVD), including vacuum powder metallurgy liquid liquid sintering method, has been in practical application.
3. Plating thickness represents the method
Because the coating thickness of the surface of diamond abrasive particles is difficult to determine directly, it is usually expressed as weight gain (%). There are two methods of weight gain representation:
Where A is the weight gain (%); G1 is the grinding weight before plating; G2 is the coating weight; G is the total weight (G=G1 + G2)
4. Effect of diamond surface coating on diamond tool performance
In the diamond tool made with Fe, Cu, Co and Ni, the diamond particles can only be mechanically embedded in the binding agent matrix because of the no chemical affinity of the above binding agent and the lack of interface infiltration. Under the action of grinding force, when the diamond grinding particle is exposed to the maximum section, the tire body metal will lose the diamond particles and fall off by itself, which reduces the service life and processing efficiency of diamond tools, and the grinding effect of diamond can not be fully played. Therefore, the diamond surface has the metallization characteristics, which can effectively improve the service life and processing efficiency of the diamond tools. Its essence is to make the bonding elements such as Ti or its alloy directly coated on the diamond surface, through heating up and heating treatment, so that the diamond surface forms a uniform chemical bonding layer.
By coating the diamond grinding particles, the reaction of the coating and diamond to metalize the diamond surface. On the other hand, the metallized diamond surface and metal body binding agent between metal metallurgical combination, therefore, coating treatment of diamond for cold pressure liquid sintering and hot solid phase sintering has wide applicability, so tire body alloy for diamond grinding grain consolidation increased, reduce the diamond tool in the use of grinding off, to improve the service life and efficiency of diamond tools.
5. What are the main functions of diamond coating treatment?
1. Improve the inlay ability of the fetal body to inset diamond.
Due to thermal expansion and cold contraction, considerable thermal stress is generated in the contact area between the diamond and the tire body, which will make the diamond and the fetal body contact belt produce miniature lines, thus reducing the ability of the tire body coated with diamond. Of diamond surface coating can improve the physical and chemical properties of diamond and body interface, through the energy spectrum analysis, confirmed that the metal carbide composition in the film from inside to outside is gradually transition to metal elements, called MeC-Me film, diamond surface and film is a chemical bond, only this combination can improve the bond ability of diamond, or improve the ability of tire body of diamond. That is to say, the coating acts as a binding bridge between the two.
2. Improve the strength of diamond.
Because diamond crystals often have internal defects, such as microcracks, tiny cavities, etc., these internal defects in the crystals are compensated by filling the MeC-Me membrane. Plating plays the role of reinforcing and toughening. Chemical plating and plating can improve the strength of low, medium and high products.
3. Slow down the heat shock.
The metal coating is slower than that of the diamond abrasive. The grinding heat is passed to the resin binding agent at the contact with the grinding particle, so that it is burned out from the instantaneous high temperature impact, so as to maintain its holding force on the diamond abrasive.
4. Isolation and protective effect.
During high temperature sintering and grinding at high temperature, the coating layer separates and protects the diamond to prevent graphitization, oxidation or other chemical changes.
This article is sourced from the "superhard material network"
Post time: Mar-22-2025
