Metal powders are used in a wide range of coating technologies and industries, just a selection are described below.
Thermal & Cold Spraying
Applying a metallic coating by thermal spray involves impacting the substrate with softened or molten particles of metal via a heat source such as plasma, combustion flame or HVOF (High velocity oxygen fuel). The particles adhere to the surface and form a continuous coating which can provide improved wear resistance, thermal conductivity, EMI/RFI shielding, anti-corrosive properties etc. to the substrate. Powders such as aluminium, zinc, copper and their alloys are typically used, spherical powders (spherical copper, spherical bronze etc.) provide good flow properties although irregular particles can also be used. Tight control of particle size distribution ensures consistent coating performance.
Cold spray coating by accelerating particles to high speed via a carrier gas is useful for oxygen sensitive coating materials such as copper and aluminium.
Tin, zinc or aluminium powders are used either individually or in combination to mechanically plate fasteners such as nuts, bolts and rivets. The plating process involves tumbling the components with glass beads, catalysts and reagents to prepare the surface before adding the metallic powder and ‘cold welding’ the coating to the component.
Paints and Inks
Metallic flake powders in particular are used extensively in a wide range of paints and inks for both decorative and functional uses.