5 Thermal Spray Coating Processes You Need to Know About

Thermal Spray Coatings are a great way to protect metal surfaces and to increase the performance of precision machinery. Thermal spraying is used for a variety of industries including aerospace, military, automotive, mining, and more.  Thermal spray coatings are applied through a variety of processes, each with its own advantages and benefits. In this article, we will discuss the five most common types of thermal spray processes and what you should know about each of them.

HVOF (High-Velocity Oxy-Fuel)

The first type of thermal spray coating is HVOF. HVOF, or high-velocity oxygen fuel, is a process that uses a specially designed torch to accelerate the coating material to a very high speed. The heated material is then shot from the torch and sprayed onto the substrate. Benefits of the HVOF thermal spray coating process include high deposition rates, excellent adhesion to the substrate, and very low porosity.

Flame Spray

Flame spray coatings use a flame to heat the coating material. Materials sprayed using this thermal spray method typically have a low melting point. The molten material is then expelled from the gun and sprayed onto the substrate. This process is often used to apply traction coatings or corrosion protection. It also requires fewer utilities and is easily set up for use in remote locations.

Arc Wire Spray

Arc spray is a thermal spray process that uses an electric arc to melt and spray the coating material. In a twin-wire system, this arc is struck at the merging tips of two oppositely charged wires made of the material to be sprayed.  At the intersection of these wires is a jet of compressed air.  As the heat from the arc melts the wire, the jet blows molten droplets forward onto the part.  Common applications for arc wire spray coatings include: repairing small areas on castings and fabricating new parts, roll resurfacing, exposed outdoor structure protection and more. Due to the wire feedstock, arc wire coatings can be deposited more quickly than other coatings and are especially useful when covering large areas.

Plasma Spray

The plasma spray coating process is the most common type of thermal spray coating. In this process, a gas is heated to tens of thousands of degrees by electric current and then passed through a narrow nozzle. The hot gas is then used to melt the coating material. The molten material is then ejected from the nozzle and sprayed onto the substrate. Plasma spray coatings are typically used to protect metal surfaces from corrosion and wear. The very high temperature of the plasma arc permits the spraying of high melting point materials such as ceramics, molybdenum, and tungsten. Because of their high melting point, thermal barrier coatings are applied using plasma spraying.

Spray and Fuse

The spray and fuse thermal spray coating method is a hybrid of thermal spraying and brazing. In this process, the coating material is applied by a conventional thermal spray process such as plasma or flame spraying. The coating material is then heated to its melting point either by a torch or furnace so that the coating particles flow together and wet into the substrate surface. Fused coatings are tougher and more durable than conventional thermal spray coatings and are typically non-porous. In many cases, the newer laser cladding process can provide a superior surface with less heat input to the substrate.

Identify The Right Process for the Coating You Need

Each of these thermal spray processes has its own benefits and applications. Hayden Corporation can help you identify the right thermal spray coating process for the coating you need. With our years of experience and wide range of coating materials, we can help you find the best way to protect your metal surfaces. Contact us today to learn more about our thermal spray coatings services.