HVOF technology generally used for WC coating application sometimes generates material oxidation and decomposition of WC coating feedstock materials during in-process HVOF deposition.
It is directly related to the high combustion temperature which is more than 3000ºC as well as the presence of oxygen in HVOF combustion products. This usually results in coating embrittlement and further reduction of service life in the condition of abrasive and erosive wear.
For tungsten carbide coating process-based powders, particle velocity exceeds 700-900 m/s, while particle surface temperature remains about 100˚c below the melting point of the metallic binder, allowing HVAF equipment to operate in a “solid-particle” spray mode. The latter is possible due to the relatively low combustion temperature of air-gaseous fuel mixtures at 3.5 – 4.5 bar chamber pressure.
The result is a formation of coatings with extremely low oxygen content as well as little, if any, thermal deterioration of carbides. Improved toughness, cohesion and low residual stresses in the HVAF sprayed layers permit routine deposition of thick coated carbide, the superfinishing of tungsten coating to an optical mirror, as well as result in noticeable improvement of fatigue resistance of the coatings.
HVAF combustion temperature below 2000°C, the surface temperature of cobalt and chromium alloy particles usually remains near their melting point.
A characteristic feature of the HVAF process is that particles are heated gently and not fused during spraying.
Uniformly high hardness and ductility, low stress and porosity result in a substantial increase in the service life of parts protected with HVAF WC-Co coatings in comparison with HVOF tungsten carbide plating versions.
Tungsten carbide coatings with cobalt (WC-Co) are highly popular for their wear resistance, ranking second only to WC-10Co-4Cr coatings. EWS's HVAF and HVOF tungsten carbide coatings exhibit exceptional resistance to sliding wear, abrasion, and erosion, even though their corrosion resistance may be slightly lower compared to WCCoCr.
Notably, EWS's HVAF WCCo coatings boast a gas-tight quality, preventing the permeation of gas and liquid at a thickness of 50 microns or 2 mils.
Tungsten carbide coatings with cobalt (WC-Co) are highly popular for their wear resistance, ranking second only to WC-10Co-4Cr coatings. EWS's HVAF and HVOF tungsten carbide coatings exhibit exceptional resistance to sliding wear, abrasion, and erosion, even though their corrosion resistance may be slightly lower compared to WCCoCr.
Notably, EWS's HVAF WCCo coatings boast a gas-tight quality, preventing the permeation of gas and liquid at a thickness of 50 microns or 2 mils.
| WCCo 88/12 Powder Properties | Wt.% |
| Tungsten Carbide | Base |
| Total Carbon | 5.3 – 5.4 |
| Cobalt | 11–13 |
Typical Applications of WCCo coatings in India
When it comes to thermal spray coatings, WC-12Co coatings are known for their superior hardness compared to WC-17Co coatings. This heightened hardness is a result of higher levels of tungsten carbide in the coating.
| Feature | S.I. Unit |
| Apparent metallographic porosity | <0.1 |
| Bond strength of tungsten carbide coating to carbon | PSI 12,000+ |
| hardness range, HV300 | 1150-1600 |
| hardness deviation from a target value, HV300 | ±60 |
| typical as-sprayed roughness Ra, microns | 3 |
| maximum coating thickness, mm | 3 |
| the maximum working temperature of the coating, °C | 510 |
The tungsten carbide WC-12Co coatings offer excellent resistance to sliding wear, impact, abrasion, and fretting at temperatures up to 510°C (950°F), especially in non-corrosive environments. For applications at even higher temperatures, we recommend considering chromium carbide coatings. These coatings, enriched with tungsten carbide, act as a shield, safeguarding substrates from the detrimental effects of fretting, abrasive grains, particle erosion, and dynamic contact with hard surfaces. Ideal for use in dry, non-corrosive settings, these tungsten carbide coatings on steel provide effective abrasion resistance.
While High-Velocity Oxygen Fuel (HVOF) technology is commonly used for WC coating applications, it often leads to noticeable material oxidation and WC decomposition during the deposition process. The decomposition of WC-Co coatings is closely tied to the high combustion temperature, typically exceeding 3,000°C (5,432°F), and the presence of oxygen in HVOF combustion products. This results in coating embrittlement, leading to a reduced service lifetime in conditions involving abrasive and erosive wear. EWS's High-Velocity Air Fuel (HVAF) systems offer a solution. These systems use gas fuel and compressed air for combustion at significantly lower temperatures while achieving higher velocities than traditional HVOF coating systems.
With the HVAF combustion temperature below 2,000°C (3,632°F), the surface temperature of Co-, Ni-, and Fe-alloy particles usually remains close to their melting point. Utilizing the EWS HVAF spraying process for depositing WC-Co coatings eliminates coating embrittlement, enhancing hardness and density. Additionally, this process reduces production costs due to higher spray rates and the use of air instead of pure oxygen.
A notable aspect of the EWS HVAF process is that spray particles are heated but not necessarily fused during spraying, setting it apart from other methods in the industry.
Assume a material that is so strong that it is resistant to scratches, wear, and even corrosion. Tungsten Assume a material so strong that it resists scratches, wear, and corrosion that’s tungsten carbide coating. This incredibly hard material, usually found as a fine grey powder, acts like a protective shield for surfaces. It keeps them safe from rust, erosion, and damage caused by friction. In short, carbide coating is the ultimate solution for making machinery and tools last longer.
Imagine a powerful oxygen-fueled jet blasting particles of tungsten carbide onto a surface. That’s HVOF tungsten carbide coating in action. These particles fuse tightly to create a durable, dense layer. This method of coating tungsten carbide is part of the broader tungsten carbide coating process, which ensures machinery parts gain exceptional resistance against wear.
Tungsten coating materials are highly valued for their hardness and strength. One of the main benefits of tc coating is that it enhances other materials, such as cast iron or tool edges, making them tougher and longer-lasting. You’ll find it used in saws, drills, and even in armor-piercing applications. Industries also rely on spray coating services to apply these protective layers efficiently on complex surfaces.
The cost depends on purpose and design. For everyday use, tungsten carbide rings can be found for $50–$100, offering durability at a budget-friendly price. Premium designs, such as wedding bands, cost more depending on added elements like gold or diamonds. Thanks to the same durability principles seen in tungsten coating and industrial spray coating services, these rings are prized for their resilience and strength.
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