Platinum Metals Rev., 2002, 46, (4), 182
ACT™ Platinum Coatings
ACT™ Platinum coatings are applied by a thermal spray deposition process. Platinum in wire or powder form is fed into an oxygen-propylene or plasma flame. The residence time within the heat source is carefully controlled to ensure that the Platinum is melted without vaporising it. A compressed gas stream fires the molten droplets onto the surface to be coated. The droplets ‘splat’ on impact and Solidify almost instantly. The large differential in thermal mass between the molten particles and the substrate means that the component normally experiences only a slight increase in temperature during the deposition process. A continuous feed of wire or powder ensures a uniform, even stream of thousands of droplets per second. Successive ‘splats’ build up to form the coating.
The thermal spray gun is controlled by a sophisticated multi-axis robot. The precise control of speed and motion obtainable ensures that even, reproducible coatings can be achieved. Coatings are applied in a purpose bulk coating booth which collects any ‘over-spray’ Platinum, thus minimising loss of metal,.
Correct preparation of the substrate material is vital to the integrity of the bond between substrate and coating. Great care is taken to ensure that the ceramic surface is in optimum condition to allow maximum adhesion of the coating. The substrate preparation methods allow the ceramic surface to be imperfect: minor defects can be rectified, but the number should be kept to a minimum.