title: Effect of heat-treatment atmosphere on the bond strength of apatite layer on Ti substrate.
abstract: OBJECTIVE
  The purpose of this study was to investigate the bond strength of apatite layer on titanium (Ti) substrate coated by biomimetic method and to improve the bonding of apatite layer to Ti substrate by optimizing the alkali heat-treatment process.
  
  
  METHODS
  Ti plates pre-treated with an alkali solution of 10 M sodium hydroxide (NaOH) were heat-treated at 600 degrees C for 1h at different atmospheres: in air and in vacuum. A dense apatite layer formed on top of the sodium titanate layer after soaking the alkali and heat-treated Ti samples in simulated body fluid (SBF) for up to 3 weeks. The bond strengths of the sodium titanate layer on Ti substrate, and apatite layer on the sodium titanate layer, were measured, respectively, by applying a tensile load. The fracture sites were observed with a scanning electron microscope (SEM).
  
  
  RESULTS
  The apatite layer on the substrate after alkali heat-treatment in air achieved higher bond strength than that on the substrate after alkali heat-treatment in vacuum. It was found that the interfacial structure between the sodium titanate and Ti substrate has a significant influence on the bond strength of the apatite layer.
  
  
  CONCLUSIONS
  It is advised that titanium implants can achieve better osseointegration under load-bearing conditions by depositing an apatite layer in vivo on a Ti surface subjected to alkali and heat-treated in air.
authors.affiliation: Centre for Material and Fibre Innovation, Deakin University, Geelong, Victoria, Australia.
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Wang
authors.forename: Yuncang
authors.initials: Y
authors.lastname: Li
authors.forename: Jianguo
authors.initials: J
authors.lastname: Lin
authors.forename: Peter D
authors.initials: PD
authors.lastname: Hodgson
authors.forename: Cui'e
authors.initials: C
authors.lastname: Wen
mesh_terms: D000468:Alkalies / Q000737:chemistry; D001031:Apatites / Q000737:chemistry; D032701:Biomimetics; D001826:Body Fluids; D020099:Coated Materials, Biocompatible; D001840:Dental Bonding; D003799:Dental Stress Analysis; D006358:Hot Temperature; D008422:Materials Testing; D010087:Oxides; D013499:Surface Properties; D013718:Tensile Strength; D014025:Titanium
chemical_list: D000468:Alkalies; D001031:Apatites; D020099:Coated Materials, Biocompatible; D010087:Oxides; C471701:sodium titanate; D014025:Titanium