title: Bone-like apatite layer formation on hydroxyapatite prepared by spark plasma sintering (SPS).
abstract: Hydroxyapatite (HA) compacts with high density and superior mechanical properties were fabricated by spark plasma sintering (SPS) using spray-dried HA powders as feedstock. The formation of bone-like apatite layer on SPS consolidated HA compacts were investigated by soaking the HA compacts in simulated body fluid (SBF) for various periods (maximum of 28 days). The structural changes in HA post-SBF were analyzed with scanning electron microscopy, grazing incidence X-ray diffraction and X-ray photoelectron spectroscopy. It was found that a layer consisting microcrystalline carbonate-containing hydroxyapatite was formed on the surface of HA compacts after soaking for 24h. The formation mechanism of apatite on the surface of HA compacts after soaking in SBF was attributed to the ion exchange between HA compacts and the SBF solution. The increase in ionic concentration of calcium and phosphorus as well as the increase in pH after SBF immersion resulted in an increase in ionic activity product of apatite in the solution, and provided a specific surface with a low interface energy that is conducive to the nucleation of apatite on the surface of HA compacts.
authors.affiliation: School of Mechanical & Production Engineering, Nanyang Technological University, 50, Nanyang Avenue, Singapore 639798, Singapore.
authors.forename: Y W
authors.initials: YW
authors.lastname: Gu
authors.forename: K A
authors.initials: KA
authors.lastname: Khor
authors.forename: P
authors.initials: P
authors.lastname: Cheang
mesh_terms: D001031:Apatites / Q000737:chemistry; D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry*; D001826:Body Fluids / Q000737:chemistry*; D018786:Bone Substitutes / Q000138:chemical synthesis / Q000737:chemistry*; D011232:Chemical Precipitation; D003460:Crystallization / Q000379:methods*; D017886:Durapatite / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D008968:Molecular Conformation; D013499:Surface Properties
chemical_list: D001031:Apatites; D001672:Biocompatible Materials; D018786:Bone Substitutes; D005740:Gases; D017886:Durapatite