Degradation and crystalline reorganization of hureaulite crystals during the manganese phosphating of a high strength steel

Effect of Surface Pretreatment on Quality and Electrochemical Corrosion Properties of Manganese Phosphate on S355J2 HSLA Steel

“…This dissolution leads to an increase of the bath pH value by the hydrogen evolution reaction (HER); (2) massive precipitation of very fine phosphate particles; (3) phosphate crystallization and growth; and (4) reorganization of the crystals, i.e., high rate dissolution and re-precipitation of the phosphate in the coating that reduce the exposed area and coating porosity. This mechanism was originally Coatings 2016, 6, 46 3 of 9 observed in the zinc phosphating process, but can be theoretically adopted for manganese phosphating also [11,16]. Dissolution of ultrafine low carbon steel wool helps to add Fe 2+ ions to the phosphate solution, reduces the first stage of phosphating causing the dissolution of substrate surface and supports the second phosphating stage.…”

“…Excellent corrosion resistance and anti-galling properties are the results of uniform crystal size distributions and high coating weight [11]. As revealed by accelerated corrosion tests, manganese phosphate demonstrates the best corrosion resistance compared to zinc and iron phosphates [12].…”

“…As revealed by accelerated corrosion tests, manganese phosphate demonstrates the best corrosion resistance compared to zinc and iron phosphates [12]. Manganese phosphate coating can be used on high strength steels for the oil and gas extraction industry [11]. Sufficient quality of phosphate coatings is reached by proper control of process and material parameters including: composition of the metal, structure of the metal surface, surface preparation, pH, bath chemical composition, time, temperature, etc.…”

“…Sufficient quality of phosphate coatings is reached by proper control of process and material parameters including: composition of the metal, structure of the metal surface, surface preparation, pH, bath chemical composition, time, temperature, etc. [8,13] There are many studies focused on corrosion properties of various phosphate coatings on various steels [8,[10][11][12]14,15] but no deeper research is performed on how sandblasting influences the electrochemical properties of manganese phosphate on HSLA steels. For these reasons, the aim of this study is to investigate this phenomenon.…”

Effect of combined surface treatment on quality and electrochemical corrosion properties of manganese phosphate on hsla steel domex 700

“…Relatívne vysoká plošná hmotnosť vrstiev MnP má za následok zvýšenie odolnosti voči korózií a vykazuje aj dobrú oteruvzdornosť, čo je dôvodom použitia mangánatého fosfátu na povrchu vysokopevných ocelí [14]. Analýza prierezu mangánatého fosfátovania vytvoreného na oceli pri teplote ~ 90 °C ukazuje, že povlak je zložený z dvoch vrstiev: z vonkajšej vrstvy bohatej na Mn a vnútornej vrstvy bohatej na Fe [14][15][16]. Niekoľko vedcov uvádza, že bez ohľadu na chemické zloženie povlaku, najmä pomer Mn/Fe, obe vrstvy (vonkajšia aj vnútorná) vykazujú rovnaký röntgenový difraktogram [14][15][16][17].…”