Thermal spray coatings are used in many different industries. The spray coatings are made of wire and molten powder, which are applied using plasma or oxy fuel combustion. The fire powers the mixture in such a manner that it creates a firm coating once it has been sprayed onto metal.
Applications for thermal spray coatings include aerospace engineering and buildings, as well as other structures where metal needs to be protected from environmental conditions.
HVOF or High Velocity Oxy-Fuel Spraying
HVOF is a spray coating process which uses a torch to spread flame where the nozzle is pointed. The rapid acceleration that this creates then speeds up the particles in the mixture. As a result, coatings applied in such a manner are thin and evenly applied. Whilst these coatings are thin, they are strong, with great adhesion.
Combustion Flame Spraying
This is a great option for any surfaces which won’t be able to cope with extreme stress. Due to the lower flame velocity, the coating applied to surfaces by this method is not as strongly adhered as with other methods. Combustion flame spraying is a popular option for low intensity applications, as it has a relatively low cost.
Using a plasma torch to heat and spray the coating, plasma spraying is a very popular option. There are a wide variety of thicknesses of coatings that can be produced in this manner, from a few micrometres right up to a few millimetres. The versatility of plasma spraying means that although powder is the most widely used coating, metals and ceramics can also be used to coat objects. This adaptability is the aspect of plasma spraying that makes it a popular option.
Vacuum Plasma Spraying
A lower impact option for plasma spraying involves completing the spraying in a vacuum. This allows lower temperatures to be used, which can cause less damage to the materials. There are a number of different gas combinations which can be used to achieve the necessary pressure for spraying. This method is often used for spraying car parts such as bumpers or dashboards.
Two Wire Electric Arc Spraying
This method uses an arc-point which is made between two electrically conductive wires. Melting of the coating occurs at the point of intersection between the wires. This arc heats the coating in a similar manner to the torch in combustion flame spraying.