Hydroxyapatite Coatings on Ti Plate via Chemical Bath Deposition

摘要

In recent years, the use of bioactive calcium phosphate coatings for biological fixation of load-bearing implants has been attracting much attention. Many techniques have been used to produce calcium phosphate, especially hydroxyapatite (HAP) coatings on metallic substrates. In this paper, a simple wet-chemical method, chemical bath deposition is reported to prepare calcium hydroxyapatite coatings on a Ti plate at relatively low temperature (95℃). The method is based on chelating calcium ions with a complex reagent and then increasing the temperature to dissociate the calcium ions, which induces the precipitation of HAP. EDTA is chosen as the complexion agent. At 60-95℃ the Ca(EDTA)~(2-) complex thermally dissociates and releases free calcium ions. Substrates used in this research are Ti plates with 0.2 mm in thickness. The substrates were gritted by metallographic Al_2O_3 paper and then treated in a solution of 2mol/dm~3 KOH at 95℃ for 1 hour. The HAP coatings were performed in a chemical bath that was heated from 60℃ to 95℃. XRD data indicated that the coatings are highly crystalline. FTIR and EDX analyses revealed that the coatings consist of Ca-deficient apatite. SEM micrographs of the coatings show that the coating is composed of evenly small crystal grains. The surface was uniform without apparent pores or agglomerates.