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Thin coating system
Keywords Sulzer Metco, Coatings, Thin film
Sulzer Metco reports that it has developed a new LPPS thin film process which makes it possible to plasma spray large areas with homogeneous, dense and thin coatings quicker and more economically than ever before. This, it is believed, has advantages where conventional thin film technologies are too expensive or where conventional thermal coating technology has reached its limitations.
Like conventional low-pressure plasma spray processes, the LPPS Thin Film process is conducted within a pressure controlled chamber (giving protection from contamination and oxidation), with effective cleaning and heating of the substrate. However, in this case, the vertical vacuum chamber is modified with higher power capacity to allow the plasma plume to be extended up to 2.5 metres with simultaneous broadening of the plume. This allows the molten powder particles to be distributed homogeneously over a wider area more quickly and thinly, but the high deposition capability of the new system provides a coating with a very dense microstructure. An area of 0.7 x 0.7 metres can reportedly be given a high quality A1203 coating, 10mm thick, in less than one minute, with a porosity of only 1 per cent or less. There is thought to be almost no limit to the materials that can be applied, provided that they have the correct particle size distribution.
According to Sulzer Metco the speed of the process and reduction in use of materials to achieve the required coating provides significant cost savings.
These characteristics are said to make it possible to consider applying plasma coatings for components where it was not feasible or economic before. These might include components needing electrical (probably also thermal) isolation or conductance; diffusion and barrier coatings; catalytic coatings; or coatings with optical properties (reflection, absorption, transmission), as well as graded and bond coatings.
Details available from: Sulzer Metco. Tel: +44 (0) 1252 525336.