Thermal spray consists of a group of processes where a feedstock material in powder or wire form is heated to a molten or semi-molten state, atomized and propelled toward a prepared substrate to form a coating.
Thermal spray application
Many types of thermal spray processes exist, including plasma spray, detonation gun, wire arc spray, flame spray, high-velocity oxygen fuel and high-velocity air fuel.
In industrial environments, technological advancements have made thermal spray more robust and affordable than ever before. Arc wire spray (Figure 1) offers the highest deposition rates at the lowest equipment costs, combined with excellent corrosion protection properties, sacrificial anode effect for cathodic protection and great adhesion values.
The arc wire spray method is used to apply zinc and aluminum coatings for corrosion control as well as engineered coatings (hard-facing/machine element coatings) for abrasion resistance, chemical resistance, lubricity, rebuilding original dimensions and wear resistance. Engineered coating offerings include aluminum bronze, Babbitt, carbides, high-nickel alloys, stainless steel and many more.
Arc wire thermal spray has the following advantages:
- Highest deposition rates among all thermal spray methods.
- No pre-heating or heat treatment is required after coating.
- No risk of thermal distortion.
- No risk of metallurgical degradation of the substrate.
- A wide range of coatings can be applied.
- No dilution of the coating by the substrate material.
- Fast turn times and superior lifecycles.
- Superior corrosion protection and bonding (adhesion).
- Operating temperature range of -50 degrees Fahrenheit to 1,000 degrees Fahrenheit and above.
- Provides sacrificial anode effect on steel.
Boiler tubes being sprayed with chromiumcarbide
Thermal spray can be used in many industrial applications such as CUI; cyclical services (ambient to 1,000 degrees Fahrenheit and above); piping; pipe valves; tanks; vessels; flare stacks; silencers; chemical reactors; heat exchangers; sheet pilling; fenders; and antislip, anti-skid, and wear- and corrosion-resistant applications.
Thermal spray coatings also have clear advantages over traditional painting:
- Thermal spray coatings last much longer.
- A variety of different materials are available (everything from metals and alloys to plastics and ceramics).
- Thermal spray coatings can be engineered to have the greatest corrosion resistance or other characteristics needed for the specific condition.
- Thermal spray coatings are more efficient and contain no VOCs. They can be applied with little to no waste.
- Thermal spray coatings cost less in the long run. Properly applied thermal spray coatings will serve significantly longer without any maintenance, compared to traditional paint. Cost savings from reduced downtime during repainting and maintenance processes are significant.
BHI Energy offers thermal spray applications as a complement to our industry-leading weld overlay services. In cases where structural integrity of the equipment is not compromised (no metal buildup required), we recommend our clients consider a thermal spray approach for their equipment protection needs.
For more information, visit www.bhienergy.com or email alex.kleiman@bhienergy.com.
