Key Characteristics of CVD Tungsten Carbide Coatings

The key characteristics of CVD tungsten carbide coatings are as follows:

1、Outstanding chemical and corrosion resistance
2、Free from through porosity, thus effectively protecting mild steel substrate from corrosive media without sealing the coating
3、Superior resistance to sulfide stress cracking
4、Provides effective protection against mineral acids such as sulfuric acid and hydrochloric acid
5、Resists Aqua Regia at room temperature
6、Superior wear resistance; Wear rate of CVD tungsten carbide coatings is four fold lower when compared to thermal spray WC, 12 fold lower than hard chrome, and 40 fold lower when compared to abrasion resistant steel AR-500
7、Demonstrates better erosion rate when compared to chrome carbide weld overlay, hard chrome, white iron, cemented carbide, and various other hard materials
8、Better fatigue resistance and toughness
9、Superior resistance to impact and deformations
10、Deposition from the gas phase enables coating of internal surfaces and intricate shapes.

A micro-photograph of a cross-section of 50-microns thick CVD Tungsten Carbide coating type T on thread. The uniform coating follows the substrate; even slight imperfections are accurately followed (magnify. 20X).

Comparison results of ASTM G65 tests of CVD tungsten carbide coating abrasion resistance against other hard materials is depicted.

Results of ASTM G65 tests of CVD Tungsten Carbide coating abrasion resistance as compared to the results for other hard materials.

Corrosion resistance of CVD tungsten carbide coatings is demonstrated.

Samples of three different coatings after salt spray corrosion tests: left - HVOF after 480 hours; centre – Hard Chrome after 288 hours; right – CVD coating type T after 480 hours.
Applications of CVD Tungsten Carbide Coatings

CVD tungsten carbide coating is suitable for applications with many different components operating in extreme erosive and abrasive atmospheres, such as critical components of metal seated ball valves, downhole tools, and pumps handling abrasive fluids.

Ball valves coated with CVD tungsten carbide coating, demonstrate increased valve life thanks to the coating as it make them scratch-proof and able to resist erosion and abrasion.

Ball valves coated with CVD Tungsten Carbide coating.

CVD tungsten carbide coating extends the life and reduces downtime costs of downhole tools such as grippers for down-hole tractors, high loading bearings pins, and mud-driven hydraulic parts for directional drilling tools.

CVD tungsten carbide coating type T is applied on outside piston and inside cylinder of a positive displacement pump transporting abrasive viscous fluids at pressures as high as 2800 psi to reduce wear, thus increasing pump life threefold.

CVD tungsten carbide coating is an ideal alternative to phase-out hard chrome plating because it involves carcinogenic hexavalent chromium, thus causing negative impact on environment, health and safety.
Conclusion

With these qualities, CVD tungsten carbide coating becomes an ideal solution to improve the performance and life of critical components of valves, downhole tools, and pumps operating in power generation, cryogenic equipment, refineries, food manufacturing, and oil and gas facilities.
About Hardide Coatings

Hardide Coatings produce a range of advanced surface engineering coatings that protect the internal and external surfaces of components from wear, erosion and acidic corrosion.

The coatings are proven to extend the life of metal parts operating in harsh environments for a variety of industries including oil & gas, valves, pumps, aerospace and advanced engineering.

Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
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