title: Effects of phosphates on microstructure and bioactivity of micro-arc oxidized calcium phosphate coatings on Mg-Zn-Zr magnesium alloy.
abstract: Calcium phosphate (CaP) coatings were prepared on Mg-Zn-Zr magnesium alloy by micro-arc oxidation (MAO) in electrolyte containing calcium acetate monohydrate (CH3COO)2Ca·H2O) and different phosphates (i.e. disodium hydrogen phosphate dodecahydrate (Na2HPO4·12H2O), sodium phosphate (Na3PO4·H2O) and sodium hexametaphosphate((NaPO3)6)). Scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray diffractometer (XRD) were employed to characterize the microstructure, elemental distribution and phase composition of the CaP coatings. Simulated body fluid (SBF) immersion test was used to evaluate the coating bioactivity and degradability. Systemic toxicity test was used to evaluate the coating biocompatibility. Fluoride ion selective electrode (ISE) was used to measure F(-) ions concentration during 30 days SBF immersion. The CaP coatings effectively reduced the corrosion rate and the surfaces of CaP coatings were covered by a new layer formed of numerous needle-like and scale-like apatites. The formation of these calcium phosphate apatites indicates that the coatings have excellent bioactivity. The coatings formed in (NaPO3)6-containging electrolyte exhibit thicker thickness, higher adhesive strength, slower degradation rate, better apatite-inducing ability and biocompatibility.
authors.affiliation: Key Laboratory for Liquid-Solid Structural Evolution & Processing of Materials, Ministry of Education, Shandong University, Shandong, Ji'nan 250061, People's Republic of China.
authors.forename: Y K
authors.initials: YK
authors.lastname: Pan
authors.forename: C Z
authors.initials: CZ
authors.lastname: Chen
authors.forename: D G
authors.initials: DG
authors.lastname: Wang
authors.forename: T G
authors.initials: TG
authors.lastname: Zhao
mesh_terms: D000085:Acetates / Q000737:chemistry; D000328:Adult; D000497:Alloys / Q000737:chemistry*; D000818:Animals; D001826:Body Fluids / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry; D002130:Calcium Phosphates / Q000138:chemical synthesis / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry; D005260:Female; D005459:Fluorides / Q000097:blood; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007101:Immersion; D007477:Ions / Q000097:blood; D008274:Magnesium / Q000737:chemistry; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010710:Phosphates / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry; D015032:Zinc / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
chemical_list: D000085:Acetates; D000497:Alloys; D017610:Calcium Compounds; D002130:Calcium Phosphates; D004573:Electrolytes; D007477:Ions; D010710:Phosphates; D014867:Water; C020243:calcium phosphate; D015040:Zirconium; D008274:Magnesium; D015032:Zinc; D005459:Fluorides; C120662:calcium acetate