HVOF Gun for Tungsten Carbide Coating
HVOF Tungsten Carbide Coatings
Hvof Gun for Tungsten Carbide Coating is an ideal process utilized to protect against rust, & corrosion to substrate surface. Thermal spray processes are utilized for a lot of conventional & creative applications & their significance is becoming more elevated and higher. Tungsten Carbide based thermal spray coatings represent one of the most important classes of coatings that find application in a broad range of industrial sectors. This paper will address a review of current applications and characteristics of this kind of coating. The most important spraying processes, namely HVOF gun (High Velocity Oxygen Fuel Spray gun) are examined, and the characterization of the coatings from the point of view of erosion and wear resistance is considered.
The Tungsten Carbide based alloys are good anti-corrosion materials, but they do have not good antiwear characteristics and can not be utilized in the seal parts of the line. From the point of view of the tribological properties the use of hard materials as thermal sprayed coatings allows to enhance drastically the in-service behaviour of the part. Quite all these Hvof Gun for Tungsten Carbide coating is produced by High Velocity Oxygen Fuel Spray to obtain a very hard coating with excellent cohesion and adhesion. This technology also allows them to acquire extremely dense coatings that show good behaviour in aggressive environments. Namely tungsten carbide cobalt-chromium based is the standard material for application in the petrochemical field and finds a place in the specification of the main companies.
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Therefore the testing of Hvof Gun for Tungsten Carbide coating produced by HVOF is an important contribution to the understanding of its capability for petrochemical purposes. This paper addresses the study and characterization of tungsten carbide thermal spray coatings.
HVOF Tungsten Carbide Spray Coating Process
HVOF Gun for Tungsten carbide coating is functioned via the HVOF thermal spray coating technique. Within this method, fuel gas & oxygen are combusted in a heightened-pressure enclosure getting temperatures up to 5,600F (3,093C). The resultant superheated, heightened tension gas is emitted via a smallish-diameter nozzle & revved down a lengthy cask at supersonic accelerations. Tungsten carbide powder is infiltrated into nozzle, where powder bits combine with running gases, achieving accelerations up to 3,000 feet per second.
If r< 0.59, the metal atoms form very simple structures with close-packed cubic or hexagonal arrangement with carbon atoms located at interstitial sites that are smaller than the carbon atom because otherwise there will be insufficient bonding resulting in an essentially unstable structure. Namely in the case of tungsten carbides the most common phases are WC and W2C both crystallising in the cubic (NaCI) structure. Tungsten carbide is durable at room temperature as cubic a-WC that melts at 2867 C. The hexagonal W2C-phase melts at a slightly lower temperature of 2750 C. WC loses carbon at an appreciable rate above 2200 C and will form a surface layer of W2C (2). Cemented carbides are composite materials of pure carbides with a binder metal of low melting point and high ductility. The term refers usually to a carbide of group 4b-6b elements of the periodic table together in a metal matrix such as cobalt or nickel. Mixtures of these metals, also together with chromium are often utilized. The selection of the binder metal relies to a large extent on its ability to wet the surface of the carbide particles to ensure safe coating cohesion. Namely, the addition of Cr to WC/Co-cemented carbide causes important property changes in terms of surface behaviour. The corrosion resistance of cemented carbide coatings is determined by both the corrosion resistance of the carbide(s) and the binder metals.
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The behaviour of tungsten carbide cobalt-chromium based has been compared with other materials that usually find application in the petrochemical specialisation: chromium carbide nickel-chromium based and Inconel 625. All these coatings have been produced by HVOF (High Velocity Oxygen Fuel) on stainless steel AISI 304 substrate. The average thickness has been 200 µm ± 50 µm.
Note that the tungsten carbide cobalt-chromium based coating, during the Slurry Test, did not exhibit a significant weight loss, therefore the graphic is senseless.
HVOF Tungsten Carbide Coating Spray Benefits
- Heightened Bond Stability
- Low Residual Pressure
- Low Porosity (Typically <0.5%)
- Heightened Wear Resistance
- Suitable Tungsten Carbide Corrosion Resistance founded on binder chemistry