ARL Center for Cold Spray - Advantages

ARL Center for Cold Spray

Cold spray offers several advantages over other coating systems and deposition processes. Being a low-temperature process, cold spray operates below the melting point of metals, requires no combustible fuels or gases, and results in very low porosity deposits. Its solid-state bonding feature, similar to explosive bonding, allows mechanical mixing of particles and substrate. High velocity impact results in plastic deformation of particles to disrupt oxide films, and provides compressive residual stresses. Low temperatures assure that the crystalline structure of the particles does not change. Low temperatures also assure that initially nano-structures particles result in nano-structured deposits. Cold spray can also be used to form high-density deposits, producing thick coatings of low oxide and porosity content and/or free-standing structures. These advantages are summarized as:


Collection of images showing: Mechanical Mixing at Interface, Cold Spray Can Produce Bulk Structural Materials to Theoretical Density, Cold Spray Can Be Used to Produce Components to Near-Net Shape, Near Net Shaped Charge Liners

Low Temperature Process

  • Below Melting Point of Metals
  • No Combustion Fuels, Gases
  • Nano-structured particles do not fuse by melting
  • Crystalline structures not altered

Solid State Bonding

  • Mechanical Mixing of Particles and Substrate
  • Similar to Explosive Bonding
  • Plastic Deformation of Particles Disrupt Oxide Films

High Density Deposits

  • Form Thick Coatings at High Deposition Rates
  • Low Oxide and Porosity Content (‹1%)
  • Form Free-Standing Structures
  • Compressive Residual Stresses

Comparison of Cold Spray and Thermal Spray:

The figure below presents the operating window for common of metal spray technologies. Compared to conventional thermal sprays, cold spray is characterized by the lowest temperature and highest velocity. The operating temperatures of conventional plasma, detonation and High Velocity Oxygen Fuel (HVOF) produce melted particles, which shrink upon cooling, leaving high tensile residual stresses. Since particles are not melted for cold spray, the resulting deposits exhibit moderate compressive residual stress. In addition, the crystalline structure of cold sprayed particles remains largely unchanged during deposition, unlike that of the melted and resolidified particles in conventional thermal sprays.

Comparison of Cold Spray and Thermal Spray

The figure below illustrates how operation at the conditions above affect the deposited material.

Slide of Flame Spray Sn & Steel Coating, 12.2% Porosity Slide of Cold Spray Sn Coating, 0% Porosity Slide of Cold Spray Al Coating, 0.83% Porosity

Last Update / Reviewed: May 19, 2015