Technology file

High velocity oxyfuel spraying

- the versatile, high deposition rate thermal spraying process for dense, high performance coatings

High velocity oxy-Fuel (HVOF) spraying can be used to deposit metal, cermet, ceramic, and polymer coatings from 50µm to 2mm thick which are characterised by low porosity and high adhesion.

HVOF spraying employs higher flow rates and pressures compared with conventional flame spraying. These factors combined with internal combustion within the HVOF gun allows a supersonic flame (with characteristic shock diamonds) to be produced.

HVOF systems employ gas fuels such as propylene, hydrogen and acetylene (TopGun and Diamond Jet) or liquid fuels such as kerosene (JP5000). Particle speeds of between 400-800 m s-1 are generated allowing dense coatings to be produced (compared to flame, plasma and arc spraying). The benefits of HVOF spraying include:

  • A wide variety of coating materials can be sprayed
  • Coating thickness of 50µm to 2mm may be deposited
  • Low heat input to substrate
  • Low porosity coatings
  • High adhesion coatings compared to other spray processes
  • Less risk of thermal degradation of material due to shorter dwell time in the flame (compared to flame & plasma)
  • Commercial process, over 80 systems in UK (>1000 global)
  • Used for new parts and reclamation e.g. hard chromium replacement.

HVOF Expertise and Resources

Established in 1990, TWI's thermal spraying group supports many industry sectors with its expertise in high velocity oxyfuel (HVOF) spraying.

The group has experience in spraying a wide variety of materials and undertake work to develop HVOF spraying for different materials and applications. TWI has 4 HVOF systems incorporated in its two thermal spraying booths:

  • JP5000,
  • Diamond Jet Hybrid (DJ2600 & DJ2700)
  • TopGun
  • HVwire
JP5000 Diamond Jet
JP5000 Diamond Jet
Top Gun HVT wire
Top Gun HVT wire

TWI also has extensive testing and characterisation facilities for assessment of thermal spray coatings and evaluating coating performance. We can also offer advice on process & materials selection.

Applications

Project work and consultancy has included applications such as:

Links:

What types of coating can I apply with HVOF spraying?
What are the advantages of HVOF spraying?
What are the disadvantages of HVOF spraying?
What are the most common applications for HVOF spraying?
What types of HVOF spraying equipment are available?
What types of metal powder are used with HVOF spraying?
What types of carbide powder are used with HVOF spraying?
Are HVOF coatings an alternative to hard chrome plating?

All TWI's confidential consultancy and project work is conducted to ISO 9001 quality standard

For immediate support or to discuss your requirements, please contact Surfacing: surfacing@twi.co.uk

Why not search the site for more information on high velocity oxyfuel (HVOF) spraying

Copyright © 2008 TWI Ltd
Information and advice from TWI and its partners are provided in good faith and based, where appropriate, on the best engineering knowledge available at the time and incorporated into TWI's website in accordance with TWI's ISO 9001:2000 accredited status. No warranty expressed or implied is given regarding the results or effects of applying information or advice obtained from the website, nor is any responsibility accepted for any consequential loss or damage.