Plasma Spray Coating

In the field of thermal spraying, there are two main types of processes: plasma spraying and combustion spraying (e.g. HVOF). Both of these methods involve heating a material to a high temperature and then projecting it onto a surface, but there are some key differences between the two. The plasma spray coating process uses a plasma torch to heat the material, resulting in a high temperature plasma plume. Material heated and accelerated in this plasma plume is then directed at the surface, where it cools and forms a coating. HVOF, on the other hand, uses combustion of a fuel gas such as hydrogen or propane to heat the material. This results in a very high speed jet of gas that is then used to accelerate material directed at the surface. The main difference between these two processes is the velocity of the sprayed material. Plasma sprayed materials tend to be deposited at lower velocities than HVOF sprayed materials, resulting in a less dense coating. Additionally, HVOF is typically used for metallic and composite materials while plasma spraying can be used for a wider range of materials, including ceramics, soft metals, and carbides. Ultimately, the choice between plasma spraying and HVOF depends on the desired final properties of the coating.

Metals, ceramics, and composites are the most common plasma spraying materials. Metals such as aluminum, chromium, and nickel are often used for their wear resistance and corrosion resistance. Ceramics such as alumina and zirconia are used for their high-temperature resistance and wear resistance. Composites such as tungsten carbide are used for their high wear resistance.

Plasma spraying is used in a variety of applications, including pumps and valves, mining, power generation, and military. The flexibility of plasma spraying makes it useful for a broad range of materials and applications from thermal barriers to wear protection to dimensional restoration.

Plasma spray coatings are more dense than conventional flame spray coatings of wire or powder. The process is capable of much higher temperatures, so that even very high melting point materials can be sprayed. Plasma spray guns are small and lightweight, and the standoff distance is short, so plasma spraying is capable of working in smaller spaces, such as tubular IDs, than other thermal spray techniques.

Plasma coating typically last for several years before they need to be replaced. However, the lifespan of a plasma coating depends on several factors, including the environment in which it is used, the type of material that is coated, and the thickness of the coating. Additionally, coatings that are used in more hostile environments will have a shorter lifespan than those used in less hostile environments.