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An Overview Of Tungsten Carbide Coatings

By Richard Patterson


Recently, the hard chromium coatings are phased out due to various performance limitations associated with them. This has been influenced by the wide application of viable high-velocity oxygen fuel tungsten carbide coatings which have gained supremacy in the engineering community, both the military and the civilian aerospace. This is because of its adhesive and cohesive abilities and forms durable coatings which are anti-wear to abrasive processes like galling and corrosion.

The coating can as well be applied by other modest ways of application to attain a higher texture coating which normally depends on the application procedures. When plasma sprays are used, it triggers the use of flame spray for secondary fusing purposes and to provide a metallic bonded coating. The essential aspect of the use of tungsten carbide as the coating powder is to ensure consistency in application and a presentable metallic surface output.

The application process entails a sequential chemical procedure. A fuel gas together with oxygen is com-busted in high pressure and temperature chamber. This produces a hot, high-pressure gas which is jetted through the minute radial nozzle. It is also accelerated at turbo speed in a long barrel. Tungsten carbide powder is then injected into the nozzle to blend with the high-velocity gas.

Then the mixture in a high velocity is injected on the substrate surface to be applied thus losing the gained kinetic energy due to an instant halt. Therefore, the particles adopt the kinetic energy by clinging together on the metal surface resulting in a dense uniform coating with low porosity characteristics. Similarly, a high bond coating is attained due to the cohesive and adhesive properties of the powder.

Some critical instances demand a specified coating texture. It is thus achieved through mixing the carbide powder with the selected binder material containing the desired characteristics. The resulting compound manifest increased hardness due to its higher boiling point. It is thus sprayed by a high-velocity oxygen thermal spray resulting in the formation of a hard and resistant to corrosion coating.

Various considerations are put in place when selecting different binder materials and chemistry; these include; corrosion, erosion, and abrasion. Thus, the coating is commonly used for extreme wear conditions. It is thus applied in coating rolling surfaces in paper production processes. The quality and thickness of the paper produced can be ascertained by the parameters applied in thermal spraying the surfaces to adapt the desired paper characteristic.

The coating technology is also applicable to power generation points, majorly coal-oriented power plants. It plays a key role in maintaining the surfaces from adverse conditions like corrosion. Similarly, the coating is also widely used in steel and metal production from the fabrication process to the finishing process. Collectively, it serves as cost reduction technique, and thus it efficiently fosters productivity.

Finally, the coating accrues a pool of benefits over other coating elements in that despite its punishing ability on operating conditions; it is the easiest mode of coating in the application. Its deposition process is faster than the anciently used conventional chrome plating. Similarly, it does not undergo the time and cost required for hydrogen embrittlement treatment.




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