This is a solid-state coating process. A high-speed gas jet is used to accelerate cold powder particles towards a surface where metal particles are deformed and consolidate on the surface upon impact.
The process takes place at a temperature much lower than the melting point of the spraying material. Cold spray coating is especially useful for applications where parts are sensitive to the temperature of the process. A low oxygen content powder is very important for this process.
Applications
Corrosion mitigation of sensitive materials
Surface restoration and sealing
Manufacture of sputtering targets
Fabrication of busbars on heated glass
Electrical and thermal conductive coatings
Biomedical and biocompatible materials on orthopaedic implants, prosthesis and dental implants
Advantages
Safety due to low temperature process
Gradient deposits
Suitable for many substrate materials
High density, low porosity coatings
Minimal substrate distortion even at very low thickness
Minimal surface preparation needed
Safer for the environment
Metastable alloys can be deposited
Thermal spray coatings
With this process, coated materials are melted or heated, then sprayed onto a surface. This is mainly used for so-called thick coatings (over 50 micrometers). Thermal spray coatings are mainly classified in 4 categories according to the source of energy used:
Flame spraying
Wire-arc spraying
Plasma spraying
High-velocity oxy-fuel coating spraying (HVOF)
Applications
Gas turbine technology
Electronics industry
Aircraft industry
Biomedical
Carbon fibres composites
Electronics
Energy
Advantages
Versatility, almost any metal, ceramic or plastic can be thermal sprayed
Cost effective mean to repair worn components and incorrectly machined parts
Rapidity, around 3 to 60 lb/hr depending on the material and spray system
Good for parts that require porosity
Technology offers good wear and heat resistance
Clearance and dimension control
Corrosion and oxidation resistance
Good electrical properties (resistance and conductivity)