In this article, we explore the limitations of HVOF Tungsten Carbide Coatings. Many of the thermal spray coatings Alphatek provides are proprietary and have been developed to meet the specific application requirements of our customers. Some are supplied specifically to customers’ own provision. Although all are applied to the highest quality and represent exceptional value, there are still limitations of such services.

And that includes limitations with HVOF Tungsten Carbide Coatings.

What Is A HVOF Tungsten Carbide Coating?

HVOF (High Velocity Oxygen Fuel) coatings is a type of thermal spray coating process which is mostly used when restoring the surface of a component. This is a surface engineering technique which better enables the life extension of components and equipment by increasing the equipment’s resistance to issues like erosion, wear, and protecting it against corrosion.

HVOF spraying mixes fluid fuel and oxygen which is then fed through a combustion chamber where it’s ignited. It results in a gas that has an incredibly high temperature and pressure and that is ejected through the nozzle at supersonic speeds.

Powder is then injected into the high velocity gas stream and it melts, but only slightly. This now combined stream of hot gas and powder is directed at the surface intending to be coated and it’s applied. The coating applied is dense and not only has low porosity but also high bond strength. Such characteristics is what gives HVOF coatings their benefits, like corrosion resistance.

HVOF Tungsten Carbide

Tungsten carbide, in its most basic form, is typically a very fine powder that is grey in colour. It isn’t just used in applications like thermal spray coatings, though. It can also be formed and pressed to create items such as jewellery, tools, or components of industrial machinery.

Tungsten carbide is actually more of a brittle ceramic but it becomes a carbide coating when it is combined with small parts metallic powder – Ni, Cr, Co. As a carbide coating, Tungsten carbide has quite a great resistance to abrasion, erosion, and wear.

What Are Some Applications of HVOF Tungsten Carbide Coatings?

HVOF Tungsten carbide coatings are very often applied to roll surfaces that are used in paper production, in the print and paper industry. In these environments, erosion, corrosion, and abrasion are some of the most common issues. Therefore, Tungsten carbide coatings and ceramic coatings are quite effective in conditions of intense wear.

These coatings are also widely used in the steel and metal production industries due to their wide range of proven, cost-saving applications across the entirety of the production process. They are incredibly effective for components that need protection from hazardous, challenging environments and operating conditions.

Similarly, HVOF Tungsten carbide coatings are commonly applied in the Power Generation Industry. They provide essential protection to the components that are exposed to extreme wear conditions.

Are There Limitations of HVOF Tungsten Carbide Coatings?

As excellent a coating HVOF Tungsten Carbide is, it still has its limitations.

  • Because of the nature of how HVOF coatings are applied, the powder sizes are very restricted. Usually only accepted in a range of around 5µm to 60µm means that the distribution needs to be a narrow size.
  • HVOF sprayed coatings can be rather complex in nature. Their properties and microstructures often depend upon multiple processing variables.
  • Only experienced and qualified personnel have the requirements to be able to provide a HVOF thermally sprayed coating. This ensures that the coating technique is operated safely and the quality of the coating overall is consistent and high quality.
  • This thermal spraying process must be performed only in a specialised thermal spray booth. All thermal spraying process have health and safety protocols to follow that ensure that it is being operated safely. Therefore, the specialised booth must have suitable sound attenuation as well as extraction facilities for dust.
  • Compared to other thermal spraying processes, like flame and arc spraying for instance, the equipment needed for HVOF is much more of an investment.
  • Actual manual operation of an HVOF spray gun in not really recommended. Automated manipulation of the gun is usually needed.
  • As HVOF spraying needs line of sight to the surface and a spray distance of 150mm to 300mm, coating internal surfaces of smaller components, especially cylindrical components, is incredibly difficult. Sometimes even impossible to achieve.

Alphatek: Your Thermal Spray Coating Specialists

The HVOF Tungsten Carbide Coating is one of Alphatek’s most commonly used thermal spray coating, applied for wear-resistance surface treatments. Safe to say, this is definitely our most popular.

For years, we’ve worked closely with our customers and been able to develop products and services that deliver only the best. Our services deliver the best value, the best quality, the best efficiency. Our service is stress-free first time and every time after that. Suited to everybody’s needs.

With our range, we have the capability and the facilities to provide services for a complex variety of parts. Small or large, individual components or part of a larger machine.

Get in Touch Today

The experience we have is unparalleled.

Our coating experience spans a cumulative 100+ years so you can trust that we’ll deliver.

Look no further than us for your metal spraying and thermal spray coating specialists. Ring 01706 821 021 to call one of our team and speak to them directly or just send us a quick email at postbox@alphatek.co.uk.