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Formation of Zn-Ca-Ni tri cation's phosphate coating on steel and study that properties

Zarei, M ; Sharif University of Technology | 2009

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  1. Type of Document: Article
  2. Publisher: 2009
  3. Abstract:
  4. A new Zinc phosphating bath, which produces coatings at relatively lower temperatures within a reasonable time by using of chemical accelerators has been devised. Improvement of the bath performance by the addition of divalent cations like calcium, nickel has been studied. Bath formulation and operating conditions have been optimized by coating weight determinations. Stable samples of phosphating formulations with and without calcium and nickel salts were prepared and the structure and morphology of the phosphate coatings were determined by using X-ray diffraction (XRD) techniques, scanning electron microscopy. ASTMB117 salt spray test and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion resistance of the phosphated carbon steels in a 0.5 mol/lit NaCl electrolyte. XRD shows that the incorporation of calcium and nickel changes the structure of phosphate coatings from essentially phosphophylite - hopeite to scholzite - phosphonicollite-phosphophyllite - hopeite with considerable reduction in grain size and a substantial improvement in compactness as evidenced by scanning electron micrographs (secondary emission). The corresponding increase in corrosion resistance has been demonstrated by salt spray tests on painted phosphated panels
  5. Keywords:
  6. Bath formulation ; Coating weights ; Divalent cation ; Grain size ; Nickel salts ; Operating condition ; Phosphating ; Salt Spray test ; Scanning electron micrographs ; Structure and morphology ; XRD ; Zinc-phosphating ; Calcium ; Calcium alloys ; Calcium phosphate ; Carbon steel ; Corrosion resistance ; Electrochemical corrosion ; Electrochemical impedance spectroscopy ; Functional electric stimulation ; Nickel ; Nickel alloys ; Positive ions ; Protective coatings ; Scanning electron microscopy ; Sodium chloride ; X ray diffraction ; X ray diffraction analysis ; Zinc ; Phosphate coatings
  7. Source: TMS 2009 - 138th Annual Meeting and Exhibition, San Francisco, CA, 15 February 2009 through 19 February 2009 ; Volume 1 , 2009 , Pages 615-623 ; 9780873397384 (ISBN)
  8. URL: https://www.tms.org/meetings/annual-09/proceedings.aspx