TWI Frequently asked questions
by Suman Shrestha
The number of applications for HVOF sprayed coatings has been growing steadily in the last two decades because of increased use of surface engineering, together with a continual drive for improved coating performance and quality. Primarily developed for wear resistance and mainly used in the aerospace industry, HVOF sprayed coatings have now found applications in many industries. Principal applications are based on corrosion and wear protection, and repair of worn components, where HVOF spraying can offer a technically superior and commercially competitive solution.
Common applications for HVOF coatings include:
- Wear and corrosion protection, e.g. subsea pump internals, impeller wear rings, valve plugs and seats (WC-Co, WC-CoCr, WC-NiCr coatings), slurry pump internals, extruder dies and tips, valve balls and seats, wire drawing equipment,butterfly valve discs, rock drill internals, compressor blades, compressor stator vanes, bearing housings, glass plungers (NiCrSiB coatings), Corona rolls and Anilox rolls (alumina and chromia coatings).
Other, less common applications include:
- Medical, e.g. biocompatible hydroxyapatite coatings on orthopaedic and dental implants.
- Electronics, e.g. dielectric coatings for electrical insulation in power hybrid circuits and heating elements.
- Spray forming e.g. manufacture of thin walled hollow cylindrical objects from pre-shaped cores by spraying of WC/Co, NiCr alloy and stainless steel.
Some examples of HVOF coatings are illustrated below.
Printing rolls coated with alumina by HVOF spraying
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