Potential of HVAF Spray Processes

The High Veloicty Air Fuel spray process abbreviated as HVAF is a high velocity flame spray process using air as the oxidizing gas. The concept behind this process is the use of particle temperatures below or around their melting point but high particle velocities such that plastic deformation at impact becomes possible and coating formation occurs. In this contribution a short historic survey is given and the typical structures and properties of HVAF coatings are compared with those of HVOF coatings. While coating quality was very high from the beginning of HVAF development, significant improvements in the deposition efficiency have occured with equipment developments over the last 10 years. Both HVAF and HVOF can produce dense coatings but their microstructural features and properties are different.