Northwest Mettech, North Vancouver, British Columbia, has developed a NanoFeed line of liquid and suspension feeders to enable delivery of submicron powders to thermal spray torches. The NanoFeed delivery systems provide the only efficient way to convey ultrafine powders to the torch. The powders are homogeneously suspended in an easy-to-transport liquid medium, which is then delivered to the torch at a precisely controlled rate. Nanofeed units may be either standalone or integrated with the spray system.
Integration of Mettech’s Axial III plasma system with NanoFeed suspension delivery device has resulted in new technology, Axial III Suspension Plasma Spray (SPS). Axial III SPS is capable of producing a large variety of unique nanostructured coatings with characteristics completely different from those deposited from powders of the same chemistry.
The uniqueness of Axial III SPS derives from its axial injection principle. This form of injection is the only one that allows nano-size (<1µm) particles and droplets to enter the plasma plume. Thermal barrier coatings (TBCs) for high temperature turbine components especially benefit from this capability. The photo shows an Axial III SPS-coated turbine blade on the right, uncoated on the left.
High end TBCs are generally produced by slow and very expensive vacuum process called electron beam physical vapor deposition (EB-PVD). Low end TBCs are thermally sprayed in atmosphere in the process called Atmospheric Plasma Spraying (APS).
Axial III SPS produces TBCs with equivalent properties to that of EB-PVD coatings, but at much lower operating and capital costs, whereas Axial III APS can economically coat the low end ones.
Other areas that can benefit from Axial III SPS are nano-ceramics and nano-cermets for power generation, fuel cells, and electronics.
