Here are just a few examples of the many materials used by Longevity Coatings for thermal spray coatings:
WC-CO • WC-NI • WC-NI-CR • WC-NI-CR-MO • CRC-NI-CR • CRC-WC-NI-CR-MO • And many more
Chromium oxide • Aluminum oxide • Yttrium oxide • Titanium dioxide • Stabilized zirconia • And many more
Super-alloys • Austenitic stainless • Refractory metals • Copper • Bronze White metals • And many more
Thermal Spray Coatings: Materials & Substrates
Thanks to advances in processing technology and material developments, the benefits of thermal spray coatings are now available for an almost unlimited variety of industrial applications—for wear resistance, corrosion resistance, electrical conductivity, dielectric uses, EMI/RFI shielding, thermal barriers and as a chrome plating alternative.
Coating materials (feedstock)
The types of materials that can be used to produce coatings vary widely. To begin with, almost all metals can be thermal sprayed as coatings. Even materials with high melting points, such as metal oxides (ceramic) can be thermal sprayed since some thermal spray processes generate temperatures as high as 30,000 °F (> 16,500 °C) In general, if a material melts, in all likelihood it can become a thermal spray coating.
But many of today’s advanced coating materials are costly and difficult to handle; for this reason, not all coatings companies are willing or able to apply them. For example, some of the earth’s most exotic alloys—e.g. Tungsten carbide, Molybdenum, Chrome Carbide, etc.– have unusual properties which must be taken into consideration. Tungsten carbide is another example. Unformed tungsten carbide from two different suppliers may have the same composition, but may have different properties– depending on the process used to produce the raw material. To ensure quality, uniformity and product consistency, Longevity Coatings requires suppliers of ceramics and tungsten carbide raw materials to adhere strictly to our own specifications and to certify each shipment.
Not only do coatings materials have their own unique characteristics; the same is true for base materials (substrates), which accept coatings in different ways. Thermal expansion rates, metal corrosion issues, flash oxidation and many other pertinent concerns are carefully evaluated during the consultation process to avoid unwanted results
While thermal spray processes are capable of producing very high temperatures, the energy of the processes themselves have little or no impact on the materials being coated; that is, the target substrate. Most of the heat generated by the process energy is in or near the thermal spray device while the substrate is typically several inches from the device. Although the sprayed droplets hit the substrate at high temperatures, the droplets are so small that their overall thermal energy content is low. These characteristics make it possible to coat even heat-sensitive materials like carbon fiber composites, plastics, thin metals and paper.
Thermal spray coatings have proved beneficial in other industrial applications as well, including: Dielectric (ceramics and polymers coatings); EMI/RFI shielding (various pure metals as well as metal alloys such as aluminum, copper, tin, and zinc); thermal barrier coatings (oxide ceramics, such as yttria-stabilized zirconia (YSZ) and other metal alloys); hard chrome plating alternatives (metals, carbides).
At Longevity Coatings, our state-of-the-art equipment enable us to apply these top quality materials to your exotic components, allowing you to benefit from their unique properties. We take into consideration many factors, which include expected service conditions (operating temperatures and environmental medium) and life cycle requirements.
The most familiar objective of thermal spray coatings is to confer wear resistance on a part or product. Some of the materials Longevity Coatings commonly uses for this purpose are high melting point ceramics such as carbides and metal oxides.
One of the most popular of these is tungsten carbide, which offers exceptionally high hardness (maximum74 HRC hardness) and excellent resistance to corrosion and to extreme temperatures below 650°C (1200°F). Also utilized frequently are oxides such as chromium oxide, which are very hard and resistant to chemical attack—a combination that makes them a good solution in service conditions characterized by both wear and corrosive attack. Several metals and even some plastics are also used as wear resistant coatings.
Corrosion Resistance & Prevention
Another common use for thermal spray coatings is to confer corrosion resistance on a substrate. Among the materials often specified for this purpose are nickel-chromium and cobalt-chromium alloys which, when deposited as coatings, have very low porosity levels (less than 1%) and can, thereby, lessen corrosive attack through porous connections. Oxide ceramics coatings are also often applied to many metal substrates for corrosion resistance.
Sometimes thermal spray coatings are used to prevent, rather than resist, corrosion. An example of this are galvanic coatings, made from materials like iron and steel alloys. Galvanic coatings are often described as “sacrificial” coatings because their express purpose is to corrode while forestalling the corrosive attack on the underlying substrate. This technology has been used as an effective alternative to paint when long-term protection is desired.
Wear + Corrosion Resistance
Some service conditions require protection against both wear and corrosive attack. Appropriate feedstock for this application are carbides with corrosion resistant metal binders; and oxide ceramics, many of which are hard and corrosion- resistant.
Electrically Conductive Coatings
Thermal spray coatings are often used to facilitate electrical conductivity. Electrical conductivity exists at some level in most materials. For the most part, electrically conductive coatings require low resistivity; accordingly, copper, aluminum, molybdenum and their alloys are among the most popular conductors. For high temp applications, iron-chrome-aluminum, molybdenum-disilicide or gradated coatings are often the materials of choice.
Electrically conductive thermal spray coatings can be applied to almost any substrate—from polymers and composites to ceramics. Considerations that must be taken into account are power levels and coating/substrate interactions under power and at temperature.