The Cold Spray Process: Cold spray, Gas dynamic cold spray, supersonic particle deposition, is a high-energy solid-state coating and powder consolidation process.  In Cold spray a high-pressure heated carrier gas, (nitrogen or helium) accelerates a metal powder through a supersonic nozzle.  The powder forms a coating (surface engineering) or free-standing component (Additive Manufacturing).

Bonding mechanism: Cold spray bonding is a combination of mechanical interlocking and metallurgical bonding from re-crystallization at high strained particle interfaces.

Compared with conventional thermal spray processes, cold spray has advantages:

  1. metal powder sprayed is not fused or melted.  The effect of heat on the coating and the substrate material is very low.
  2. The high kinetic energy of the metal powder sprayed and the high degree of  the metal powder deformation on impact with the substrate produces a homogenous and dense coating.
  3. The range of coating thicknesses varies from 100 micron up to 5 centimeters or more. 
  4. Metal coatings have the same physical and chemical properties as the properties of the base material. 

Cold Spray can create mixtures of metallic / nonmetallic materials to form a coating or free­-standing structure.   

Some Cold Spray Applications:

  • Corrosion-resistant coatings (zinc and aluminum),
  • Dimensional restoration and repair (nickel, stainless steel, titanium, and aluminum),
  • Wear-resistant coatings (chromium carbide – nickel chromium, tungsten carbide – cobalt, and tungsten copper),
  • Electromagnetic interference (EMI) shielding of components and structures,
  • High strength dissimilar material coatings for unique manufacturing solutions
  • Field repair of components and systems.

Characteristics of Cold Spray

Cold spray is an efficient method for the application of Metals, Metal Alloys, and Metal blends for numerous applications:

  • Extremely low heat input
  • Structural and mechanical properties of parent metal
  • No real limit on deposition thickness
  • High deposit efficiency typically > 80%
  • Bond strengths > 10 ksi
  • Coating Strengths > 40 ksi
  • Porosity commonly below 1%
  • Powder microstructure and properties are preserved
  • No oxide formation,
  • No alloy decomposition,
  • No carbon, or combustion product entrapment
  • Compressive residual stresses in coating