Now showing 1 - 2 of 2
  • Publication
    Fabrication of calcium phosphate coating on pure magnesium substrate via simple chemical conversion coating: surface properties and corrosion performance evaluations
    The main objective of the current work was to fabricate calcium phosphate (CaP) coating on 99.9% purity magnesium, Mg substrate through simple chemical conversion method and evaluated the surface properties and corrosion performance of the coated substrates. The chemical conversion method was done by immersing the samples inside primary phosphating bath and followed by secondary treatment in alkaline solutions. The coated samples from the primary (PRI) and secondary (SEC) coating treatment were analyzed from morphological, topographical, and phase analysis aspects. The corrosion behaviour of the coatings inside simulated body fluid was assessed by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). The PRI and SEC coated were composed of dicalcium phosphate dehydrate (DCPD) and hydroxyapatite (HA), respectively. Both of the coatings improved the corrosion resistance of the Mg substrate. The corrosion potentials, Ecorr of the coated samples becomes nobler compared to the bare substrates. EIS shows that the polarization resistance, Rp is improved about 40 and 2 times fold for PRI and SEC compared to the uncoated samples. Furthermore, PRI shows better corrosion resistance compared to SEC due to lower porosity along with thicker and better coating coverage.
  • Publication
    Synthesis and process evaluation of calcium phosphate coatings depositions on pure magnesium via simple chemical conversion method
    (Universiti Malaysia Perlis (UniMAP), 2018-12)
    Mohd Amin Farhan Zaludin
    ;
    ; ;
    Azmi Rahmat
    ;
    Simple chemical conversion has been employed in order to coat calcium phosphates (CaP) on magnesium (Mg) substrate. The Mg substrates were coated in a primary phosphating bath before secondary treated with an alkaline solution of sodium hydroxide, NaOH. In this paper, the fabrication process of the coatings via simple chemical conversion method were discussed and evaluated in terms of electrochemical, phase analysis, and microstructural aspects. XRD diffractogram confirmed that the primary coating composed of dicalcium phosphate dehydrates (DCPD) and after the secondary treatment, the DCPD transformed into more stable hydroxyapatite, HA. The microstructural observations show that the coating is composed of flower-like shape crystallites. Besides, the potential-time curves of both primary and secondary coated samples suggests that the minimum deposition time for better coverage of the coatings is 30 minutes.