Development of Novel Cooling and Temperature Monitoring for High Velocity Oxygen Fuel (HVOF) Coating Applications

Temperature control is a major concern during High Velocity Oxygen Fuel (HVOF) processing in the aerospace industry. Typically, temperature must not exceed 300oF to prevent heat damage/ tempering of the substrates for steel alloys, and even lower temperature requirements for aluminum and titanium alloys. Shop air cooling has traditionally been the most widely utilized temperature control cooling medium when applying HVOF coatings to aircraft components such as airframe, engine/propeller, and landing gear components, because it is readily available in the shop environment. However, in many cases shop air has proven to be inadequate for controlling substrate temperatures. Consequently, longer off-part dwell times to allow for component cooling has become common practice – resulting in significant powder and gas consumption – both of which cost money. Additionally, the traditional temperature monitoring system has been a continuous reading single point infrared gun aimed at a single location on the component being sprayed. Although this is a widely accepted method in the HVOF community, it’s only good for measuring localized areas, whereas part temperature will vary along the length of the components particularly for parts with complex geometries. This compounds the temperature issues and makes optimization of temperature control very difficult.