Thermal Spray Processes: HVOF, HVAF, Plasma, Arc, Cold Spray

Thermal spray processes cover a family of methods that apply a protective coating by accelerating particles toward a surface and building up a layer, one pass at a time. That layer can fight abrasion, corrosion, heat, and general wear, depending on the material and the process used. In many shops, the same part may also need preparation work first, then finishing afterward, so the coating performs the way it should in real production. The goal is simple: keep components running longer, reduce downtime, and help parts stay within spec.

HVOF and HVAF

HVOF, short for High Velocity Oxygen Fuel, is known for producing very dense coatings with strong bond strength and low porosity. That matters when parts face aggressive wear, sliding contact, or harsh chemical exposure. HVAF, or High Velocity Air Fuel, is similar in concept, but it uses air instead of oxygen, which can reduce heat input and help control oxidation for certain materials. In practice, these processes are often chosen when you want high performance without adding a bulky coating thickness. Many teams lean on them for carbide-based coatings and other wear-focused blends used on rolls, shafts, and tooling surfaces.

Plasma Spray

Plasma spray uses a plasma jet to heat feedstock and propel it onto the part, making it a strong option for ceramics and other high-temperature materials. That flexibility is a big reason plasma is popular in applications where heat resistance, electrical insulation, or thermal barrier behavior is required. It can also be used with metals and cermets, though material choice and parameters matter a lot. Because plasma spray can handle a wide range of powders, it is often the “go-to” process when the coating requirement is more specialized than pure wear resistance. When designed correctly, the result is a functional surface that supports performance without forcing a full redesign of the component.

Arc Spray

Arc spray, sometimes called twin wire arc, melts two consumable wires with an electric arc and atomizes the molten material with compressed air. It is often selected when coverage speed and cost efficiency matter, especially on larger parts. Many facilities use arc spray for corrosion protection, dimensional build-up, and general-purpose metallic coatings. While it may not always match the density of HVOF class coatings, it can be a practical choice when the service environment and performance targets fit the process strengths. With the right surface prep and finishing plan, arc spray coatings can deliver reliable, repeatable results.

Cold Spray

Cold spray accelerates powder particles to very high speeds without fully melting them, which keeps heat input low. That helps when you want to limit thermal distortion, protect base metal properties, or avoid oxidation issues tied to high temperatures. Cold spray can be used for restoration, dimensional recovery, and certain corrosion protection needs, depending on material selection. It is also useful when the part cannot tolerate the heat of more traditional thermal spray methods. In real-world repair work, this can open doors for components that would otherwise be too risky to coat.

How We Help You Pick the Right Process

At A&A Coatings, we match the process to the problem, then back it up with solid prep and finishing so the coating performs as intended. Undercut pre-machining sets the stage for proper coating thickness and adhesion, while finishing services and roll grinding help hit the final dimensions and surface requirements. If you are weighing HVOF, HVAF, plasma, arc, or cold spray for a specific part, contact us to discuss your goals and request a quote.