Phosphate Films Modified by Organic Compounds

Anti-corrosive films can be produced on copper and its alloys by immersion in certain phosphonic acid, RP0(0H 2, solutions. Copper phosphonate salts are formed which increase the solderabiUty and tarnish resistance of the surface. They are superior to copper phosphate films. Metal phosphonate films are useful in some dental products [20] (see below). 

The phosphating process can be carried out with almost non-aqueous liquids. These liquids contain -0.1% HjO and are based on homogeneous mixtures of phosphoric acid and an organic solvent such as methylene chloride with a solubilising agent [21]. 

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