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Is it possible to thermally spray onto non metallic surfaces?
Yes, metal spray coatings can also be applied onto non metallic substrates such as concrete, plastics, carbon fibre reinforced plastics, graphite, glass, foams.
What is the maximum substrate temperature during thermal spray processing?
Substrate temperature can be controlled by adequate process application method (feeds, speeds, cooling, etc...). The substrate temperature is usually limited to 160 degC. For some sensitive applications it can be controlled to 60 degC if required.
What is the component size limitation for thermal spray processing?
Most of the thermal spray processes are carried out in air. Therefore the process operating window is governed by the size of manipulation equipment and booth size.
Can thermal spray coatings be applied as a electrolytic hard chromium plating replacement alternative?
High Velocity Oxygen-Fuel ( HVOF ) thermal spray coating technology can be used to apply metal alloy coatings and ceramic/metal such as tungsten carbide/cobalt/chromium (WC-CoCr) coatings showing high density and very good adhesion to substrate material. Extensive research & development programs initiated by Aerospace & Defence organisations has led to recognition of HVOF tungsten carbide coatings as one of the most successful candidates for hard chrome plating replacement. The evaluation proved equivalent or better performance of HVOF coatings in comparison to electrolytic hard chrome plating under wear, fatigue, corrosion, fluid leakage testing. These findings led to specification of HVOF coatings for use in landing gear of latest aircraft designs such as Aibus A380, Boeing 787, F34, X-45, Airbus A350.
What is typical surface finish of thermal spray coating?
In as-sprayed condition surface roughness of thermal spray coatings is defined by many factors such as starting powder grain size, material chemistry, process used, etc... Typical roughness of as-sprayed coating can be measured between 3 - 15 micrometers Ra. Most coatings such as HVOF tungsten carbides or plasma sprayed ceramics can be finished by diamond grind to achieve 0.4 micrometers Ra. Further enhancement of surface characteristics can be achieved by lapping, honing or diamond super polishing. These methods allow finishes of 0.025 - 0.2 micrometers Ra.