Now Playing: Thermal Spray Coatings The Processes
  • Description:  Longevity Coatings, Allentown, PA-based company, specializes in four main thermal spray coating processes. They are TWIN ARC. This process is often used for heavy coating build-up and salvage/repair applications, where very hard surfaces are required. In this example, we are rebuilding the journal surfaces of an agitator. Longevity’s computer-controlled system ensures coatings of consistency and repeatability. PLASMA (NON-TRANSFERRED ARC) Here, a nitrogen hydrogen plasma plume is used to deposit a plasma coating of chromium oxide to a shaft. Because of the extreme temperatures reached with plasma, often up to 30,000°F, this process is ideal for high melting point materials such as chromium oxide, aluminum oxide, other ceramics as well as refractory materials. DIFFUSION BONDING. This process produces a fully dense hard surfacing with a metallurgical bond. In this example, a nickel chromium hard-facing alloy coating is being applied. A post-treatment will bring the coating to its plastic state and it will be densified in the process. HVOF (HIGH VELOCITY OXYGEN FUEL). Today’s standard for applying carbide and metal coatings. In our version of HVOF, the gases go through a converging diverging nozzle, with gas velocities reaching near 8000 fps. Use of this extremely high velocity torch produces coatings with near wrought densities and unsurpassed bond strength—which is particularly crucial when applying tungsten carbide coatings. For more information, visit us at http//