How does cold gas spraying work?
Cold gas spraying is the most recent method in the field of thermal spraying.
In comparison to conventional thermal spray processes, cold gas spraying offers special advantages, because the spraying material is neither fused nor melted during the process. Thus, the thermal influence on the coating and the substrate material is minimized.
The high kinetic energy of the particles and the high degree of deformation during the impact on the substrate that is connected with it, allows the manufacturing of homogenous and very dense coatings. The range of coating thicknesses varies from just a few hundredths of a millimeter up to several centimeters.
There are mainly metallic coatings produced, which physical and chemical properties barely differ from the properties of the base material.
With the latest system technology of Impact Innovations GmbH a process gas - preferably nitrogen or helium - is put into a spray gun with a pressure of up to 50 bar (725 psi) and is heated up to a maximum temperature of 1100 °C (2012 °F) in the gun housing.
The subsequent expansion of the heated and high pressurized gas in a convergent-divergent nozzle down to ambient pressure results in the acceleration of the process gas up to supersonic speed and, at the same time, in the cooling down of the gas to a temperature below 100 °C (373 °F).
The spray powders are injected in the convergent section of the nozzle by using a powder feeding unit and carrier gas and are accelerated to a particle speed of up to 1200 m/s in the main gas stream.
In the highly focused spray jet particles impinge the - in most cases untreated - surface of the component, deform the particles and form a strongly adhesive/cohesive and low-oxide coating.
Learn more in this video:
Particle velocity as a measure of layer quality and efficiency
What can be coated by cold gas spraying?