May 15, 2017
Perhaps the definition of tungsten carbide coating and many people have some understanding, and for their production methods, it is a little strange. The tungsten carbide coating by HVOF spraying tungsten carbide cobalt based alloy powder or nickel tungsten carbide alloy powder and chromium based alloy powder of tungsten carbide hardness can reach HV1200 temperature of 850 degrees, so that the valve spare parts,wear resistance,corrosion resistance, high temperature resistance, oxidation resistance. More than manual welding, chrome, carburizing, quenching and tempering, process, production efficiency can be increased more than 2 times, the production cost is reduced by more than 50%, service life can be extended several times.
The tungsten carbide coating, interstitial carbon atoms embedded in tungsten metal lattice, does not destroy the original metal lattice, formed interstitial solid solution, so it is also called the interstitial (or insert) compound. Tungsten carbide by high temperature heating a mixture of tungsten and carbon, hydrogen or hydrocarbon can accelerate the reaction if. Oxygen containing compounds for preparation of tungsten products, and ultimately must be vacuum treatment at 1500 DEG C, to remove carbon dioxide. Tungsten carbide should be machined at high temperatures, making cutting tools, structural materials, kiln jet engine, gas turbine and nozzle.
The corrosion and corrosion of super hard coating, including those containing tungsten carbide coatingsare widely used in mechanical engineering used in the production of various products and tools. This coating has high corrosion resistance, high chemical resistance and high abrasion resistance, thus significantly prolonged mechanical engineering products in the harsh operating conditions and tool life.
However, the rate of synthesis of tungsten carbide is very low, and when the tungsten carbon layer growth, the internal stress of the coating increased sharply, resulting in coating delamination. So through the PVD method cannot produce a sufficiently thick coating. In addition, the nature of physical vapor deposition method is not suitable for coating deposition with complex shape parts, the it is unlikely that the coating is deposited on the covered part relative to the X-ray part.
Chemical vapor deposition (CVD) eliminates these disadvantages. The.CVD method can be used to deposit high wear resistance and high corrosion resistance coatings on substrates and components with complex shapes
In a typical CVD process for composite coating deposition, heating in the reaction chamber and the substrate, pre mixed gas phase reagent into a reaction chamber.The composition and process of change of the reaction mixture parameters (substrate temperature, the reaction mixture, the reaction mixture velocity, total pressure, the gas temperature), can be a variety of coatings.
In the CVD method of tungsten carbide coatingdeposition, only the fluoride method may form tungsten carbide with high quality at low temperature. In order to achieve this purpose, can be in the CVD process of six tungsten hexafluoride, a mixture of hydrogen and carbon containing gas by thermal decomposition.
A variety of reagents can be used as carbon containing gases such as two methyl ether, amine, propylene, etc. one or two kinds of tungsten carbide can be synthesized by one of them.
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