In Combustion Wire Flame spraying, the feedstock material in the wire form is melted in the flame and atomised using compressed air to form fine spray. Flame spray uses the chemical energy of combusting fuel gases to generate heat. A stream of air then atomizes the molten material and propels it toward the workpiece. When the spray contacts the prepared surface of a substrate material, the fine molten droplets rapidly solidify forming a coating. Oxyacetylene torches are the most common, using acetylene as the main fuel in combination with oxygen to generate flame. Spray rates for materials such as stainless steel is in the range of 0.5 to 9 kg/h (1 to 20 lb/h). Again, lower melting point materials such as zinc and tin alloys spray at much higher rates. Substrate temperatures often range from 95 to 205 °C (200 to 400 °F) because of the excess energy input required for flame melting. In most thermal spray processes, less than 10% of the input energy is actually used to melt the feedstock material.
 
 

Characteristics of Wire Flame Spraying Process Coatings

  • The subjects to be sprayed are not affected by high temperature, which keeps the dimensional stability and morphological stability, causes no cracks, no strength reduction.
  • The coating with broad range of its thickness is available.
  • The coating contains harder particles than those of original materials and hard ingredients including metal oxide, nitride, carbide and etc., which provide high level of wearing resistance.

Common Materials Sprayed

  • Zinc and aluminium for anti-corrosion cathodic coatings on steel
  • Nickel/aluminium composite wire for bond coats and self-bonding coatings
  • Molybdenum for bond coats
  • Molybdenum for hard bearing applications, excellent resistance to adhesive wear, used on piston rings, synchro mesh cones and journals.
  • High Chromium steel for many applications requiring hard and wear resistant coating
  • Bronzes, Babbitt for bearing applications
  • Stainless Steels, Nickel and Monel for anti-corrosion and wear
  • Aluminium, nickel/aluminium for heat and oxidation resistance