Here we describe the main features of the spray materials. We therefore can immediately start to discuss the required features for a specific application.
Zinc Wire for Corrosion Protection
As one of the most common thermal spray coatings for steel to prevent corrosion, zinc is often used for protection against moisture, corrosion, and salt in structural steel, bridge parts, and other marine components. To create a strong corrosion protection layer of appropriate thickness and surface preparation for paint adhesion, zinc coating is built up relatively quickly to create a strong sacrificial corrosion layer.
Tungsten Carbide for Wear Resistance
Thermal metal sprays are increasingly used for components that suffer abrasion, are in sliding contact or are subject to erosion. The hardest of all thermal metal sprays is Tungsten Carbide which is normally applied using high-velocity thermal spray processes. Pumps, valves, shafts, wear plates, wear strips and many other wear prone items can benefit from being coated with a Tungsten Carbide spray.
Aluminium for High-Temperature Oxidation
Aluminium coatings are capable of withstanding high temperatures. They form a stable oxide layer, and can be used to spray components such as exhausts, furnaces, etc. Above approximately 500 °C the coating will oxidize and then scale, so such components must cycle between high and low temperatures. Weight saving is important for aerospace and automotive applications.
Ceramic Oxides for Electrical Insulation
Alumina (and other Ceramic Oxide) coatings are extremely hard and provide high levels of wear resistance. In addition to wear resistance they are also highly electrically insulating making them ideal for applications where roller shafts in printing machines are a classic example. In addition to wear resistance, these coatings are also extremely resistant to current and can be ground to very close tolerances after application.
Copper and Bronze for Bearing Surfaces
Copper-based materials are used for applications that require a high level of conductivity or for low friction bearing surfaces. Bronze coatings are used to form bearing surfaces in bearing housings and bushes. See TWI’s job knowledge guides on thermal spray processes, for specialist material guidance.
Thermal Sprays is covered in more detail at https://www.poeton.co.uk/surface-treatments/thermal-metal-sprays/.
Matching the right material to the specific wear, corrosion or thermal requirements of a particular job is what truly makes a thermal spray coating of value.
