Coating Materials

Materials we apply

If it melts, it can probably be sprayed

Almost all metals can be thermal sprayed. Some processes reach temperatures as high as 30,000 °F (over 16,500 °C), hot enough for high-melting-point oxide ceramics. Coating materials are specified based on expected service conditions, such as operating temperature and environment, and on life-cycle requirements.

Wear resistance

The most common goal, typically met with high-melting-point ceramics such as carbides and metal oxides. Tungsten carbide offers exceptionally high hardness (up to 74 HRC) and resists corrosion and temperatures below 1,200 °F (650 °C). Chromium oxide is very hard and resists chemical attack, so it is often used where wear and corrosion occur together.

Corrosion resistance and prevention

Nickel-chromium and cobalt-chromium alloys deposit with very low porosity, less than 1%, which limits corrosive attack through connected pores. Oxide ceramics are also widely used on metal substrates. Galvanic coatings go a step further: they are sacrificial, corroding in place of the substrate, and are an effective alternative to paint for long-term protection.

Wear plus corrosion

Carbides with corrosion-resistant metal binders, and oxide ceramics, many of which are both hard and corrosion resistant.

Electrical conductivity

Copper, aluminum, molybdenum and their alloys are the most popular conductors. For high temperatures, iron-chrome-aluminum, molybdenum disilicide or graded coatings are often the choice. Conductive coatings can go on almost any substrate, from polymers and composites to ceramics.

Other uses

Dielectric coatings (ceramics and polymers), EMI/RFI shielding (aluminum, copper, tin, zinc and their alloys), thermal barriers (oxide ceramics such as yttria-stabilized zirconia), and hard chrome replacement (metals and carbides).

Material consistency

Advanced coating materials are costly and difficult to handle, and not every coater is willing or able to apply them. Exotic materials such as tungsten carbide, molybdenum and chrome carbide have unusual properties that must be taken into account. Two suppliers’ tungsten carbide can share a composition yet behave differently, depending on how the powder was made. That’s why we require suppliers of ceramic and tungsten carbide powders to meet our own specifications and to certify every shipment.

Substrates

Base materials accept coatings differently. Thermal expansion, corrosion, flash oxidation and other factors all affect how a coating performs on a given substrate.

Thermal spraying puts little heat into the part. Most of the heat stays in or near the spray gun, the part sits several inches away, and the tiny droplets carry little thermal energy. That makes it possible to coat heat-sensitive materials such as carbon fiber composites, plastics, thin metals and even paper.