Protective coatings deposition methods

The above analysis of coating deposition methods visualizes that Cl impregnated in coating compositions requires specific technological operations. These technologies, equipment and methodology have rightfully occupied a place in rust protection means of metal ware. 

For forming a protective layer, dependent on the nature of the material, a vacuum vapor deposition method, a sputtering method, a plasma polymerization method, a chemical vapor deposition method or a coating method, can be applied. ... 

Aqueous deposition methods are used to apply conversion coatings for decorative and protective reasons. These conversion coatings are formed by immersing the substrate metal in an aqueous solution of chromic acid, chromate or dichromate salts. For the deposition to occur activating ions such as sulfate, nitrate, chloride, or fluoride must be added. Then as hydrogen is generated by the attack of the activating ions some of the chromium ions are reduced to form a hydrated chromium chromate which is deposited on the substrate surface. 

The substrate independent nature of iCVD enabled to encapsulate a paper-based photovoltaic (PV) array by deposition of a p(PFDA) layer to protect the device and extend its lifetime. Since no solvents are involved in the deposition method, the polymer electrodes were gently coated with the hydrophobic polymer. The coated array was folded and submerged into a water bath during the operation without affecting the performance of the device [65]. 

Special attention must be paid to solving specific problems in sol-gel processing or coat-ing/metal systems. A clear example are the aluminium alloys used in the aircraft industry which, together with the low curing temperatures needed to avoid the loss of mechanical properties, demands high protection from potential substitutes for the current protection systems. Alternatively, new sol-gel deposition methods should be developed so that the coating process can be implemented on an industrial scale. 

Protection of niobium and its alloys from oxidation in air is accomplished by coating, e.g. with zinc deposited by holding in zinc vapour at 865°C or coating with a layer of chemically stable oxide, nitride or silicide. Silicide coatings applied by pack cementation, fused slurry or by electrolytic methods have been found to be one of the most effective means of preventing oxidation of the metal. 

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