Multifunctional sol-gel derived thin film based on nanocrystaline hydroxyapatite powders

Abstract

The aim of this work was to prepare bioactive hydroxyapatite coatings by sol-gel method and to study the effect of thermal treatment temperature upon the bioactivity and corrosion protection of these coatings on Ti6Al4V alloy. The application of (DTA/TGA) and (XRD) has provided valuable information about the phase transformation, mass loss, identification of the phases developed, crystallite size and degree of crystallinity. (SEM/EDX) has been applied to study the surface morphology of coated samples before and after immersion in simulated body fluid (SBF) to detect the biomimetic precipitation of the bonelike apatite. The obtained results show that all the prepared samples are ceramic nanocrystalline with crystal structure and composition like hydroxyapatite, with little deviations from that present in the human bone. The bioactivity of the studied samples is found to be closely related to the thermal treatments applied. That is, the bioactivity decreases as the temperature of the thermal treatment increase. Coatings from such prepared hydroxyapatite sol have been accomplished by dip-coating technique on non-toxic Ti6Al4V alloy for biomedical applications. The corrosion behaviour of the resulting hydroxyapatite coatings in a (SBF) has been studied by electrochemical impedance spectroscopy (EIS). The hydroxyapatite coated Ti6Al4V alloy displayed excellent bioactivity when soaked in the (SBF) and acceptable corrosion protection behaviour.

Triethylphosphite as a network forming agent enhances in vitro biocompatibility and corrosion protection of hybrid organic–inorganic sol–gel coatings for Ti6Al4V alloys

“…This method offers many advantages (high purity and homogeneity, low processing temperatures, reduced thickness, simple and cheap preparation) for the production of coatings on materials including Ti6Al4V implants. [8,9] Organic-inorganic hybrids based on siloxane bonded units prepared by a sol-gel route have unique properties that arise from the synergism between the properties of both components. [10] We have previously reported on the use of hydroxyapatite in organic-inorganic hybrids to improve biocompatibility and corrosion resistance, however, the combination of silane or mixture of silanes with a phosphorous precursor may be a more efficient method to increase the corrosion protection and bioactivity of metal coatings.…”

Influence of substrate composition on corrosion protection of sol–gel thin films on magnesium alloys in 0.6M NaCl aqueous solution

“…The inorganic-organic hybrid coatings were deposited on the AZ31 and AZ61 by using dip coating technique [25] with a withdrawal speed of 9 cm/min and holding time of 60 s. The coated MAPTMS/TMOS-AZ31and MAPTMS/TMOS-AZ61 alloys were then placed in a furnace for 2 h at 120 o C for curing. The rest of MAPTMS/TMOS sol was placed 12 hours at 120 o C and crushed to convert it into a powder form.…”

Controlled Rate Thermal Analysis (CRTA) as New Method to Control the Specific Surface in Hydroxyapatite Thin Coatings

“…The corrosion behavior of the HA ilm/Ti6Al4V system was evaluated by applying electrochemical impedance spectroscopy (EIS) [21,31,32]. These electrochemical measurements were performed using an AutoLab potentiostat/galvanostat PGSTAT30 equipped with a FRA2 frequency response analyzer module (EcoChemie, The Netherlands).…”

“…These impedance spectra can be ascribed to the typical behavior of porous thin ilms deposited on metal substrates with high corrosion resistance [21,31,32,46,47]. In the irst approach, the single electrical equivalent circuit EEC1 shown in Figure 10a can be used to describe the electrochemical behavior of these systems.…”