Phosphating of Carbon Steel in Concentrates, Containing in Various Ratios Zinc and Manganese Phosphates

Phosphating, originally intended mainly to protect metals from corrosion using relatively thick layers, is known to be one of the most important and widely used forms of metal surface pretreatment. Its range of applications nowadays has expanded considerably, including as solid lubricants in wire drawing, calibration and cold forming of metals, for electrical insulating coatings, as a sublayer prior to the application of varnish and polymer coatings, etc. The results obtained when phosphating low carbon steel in phosphate concentrates with different ratios of the zinc and manganese phosphates, contained therein, are presented in the proposed work. The main parameters characterizing the phosphate concentrates – density, pH, electrical conductivity, total and free acidity have been determined. The influence of temperature and concentration of phosphating solutions on the mass/thickness of the coatings and on the dissolved metal of the substrate, depending on the duration of the phosphating process, was investigated. The structure, elemental and phase composition of the phosphate coatings obtained have been determined by various physical – analytical methods.