Physicochemical Investigation of Pulsed Laser Deposited Carbonated Hydroxyapatite Films on Titanium

Abstract

Carbonated hydroxyapatite (CHA)-coated titanium can find wide applications as bone substitute implant in bone and dental surgery and orthopedics, promoting osseointegration with a host bone and ensuring biocompatibility and bioactivity. In this work, carbonated hydroxyapatite films were prepared on titanium substrates by pulsed laser deposition at different substrate temperatures ranging from 30 to 750 degrees C. The properties of films were investigated by scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray diffraction, and Fourier transform infrared spectroscopy. Vickers microhardness measurements of the composite film-substrate systems were performed, and the intrinsic hardness of films was separated from the composite hardness using a "law-of-mixtures" approach and taking into account the indentation size effect. The prepared CHA films are nearly stoichiometric with a Ca/P atomic ratio of 2.0-2.2. The films deposited in the 30-500 degrees C temperature range are about 9 microm thick, amorphous, having an average roughness of 60 nm. At higher temperature, 700-750 degrees C, the films are about 4 microm thick, show a finer surface morphology and an average roughness of 20 nm. At 750 degrees C the films are amorphous, whereas at 700 degrees C they are crystalline and textured along the (202) and (212) directions. The intrinsic hardness of the films increased with an increase in substrate temperature, being as low as 5 GPa at 30 degrees C and reaching a high value of 28 GPa at 700 degrees C. The rich information gained by the joint use of the mentioned techniques allowed a comprehensive characterization of this system.

Calcium orthophosphate deposits: Preparation, properties and biomedical applications

“…However, for plasma sprayed HA coatings on tungsten, the numerical values of Young's moduli in both tension and compression measurements evaluated by the cantilever beam bend test were found to be below 6 GPa [31]. Interestingly that hardness of the CaPO 4 deposits were found to increase with the substrate temperature increasing, being as low as 5 GPa at 30 °C and reaching a high value of 28 GPa at 700 °C [263].…”

“…The substrate heating is necessary to ensure the formation of a highly crystalline and phase pure deposits. In addition, to prepare deposits with the desired fine texture and roughness, the substrate temperature could be varied [125,263,285].…”

Improved bio‐implant using ultrafast laser induced self‐assembled nanotexture in titanium

“…[18][19][20] These techniques are able to create a porous structure on complex shapes, but do not produce a surface topography with the varied size scales shown to be beneficial in orthopaedic applications. Other laser technologies have been used to first pattern grooves and ridges onto silicon upon which biocompatible materials such as titanium were then coated.…”

“…16 Certain texture patterns have also been able to control cell growth, being more preferable to osteoblast adhesion than to other cell types. 17 The most common use of laser technology in texturing metal implants has been to create a porous structure by adding layers of small metal particles which are melted or [18][19][20] These techniques are able to create a porous structure on complex shapes, but do not produce a surface topography with the varied size scales shown to be beneficial in orthopaedic applications. Other laser technologies have been used to first pattern grooves and ridges onto silicon upon which biocompatible materials such as titanium were then coated.…”

Thermal expansion of type A carbonate apatite

“…into three types: type A substitutes the OH site named type A carbonate apatite (Ca 10 (PO 4 ) 6 CO 3 ), type B for the PO 4 site, and type AB for both OH and PO 4 sites [10]. Recently, Rau et al described a pulsed laser deposition of carbonate apatite on titanium for ensuring biocompatibility and bioactivity, of which thicknesses were controlled by the substrate temperatures below 750 • C [11]. Synthetic methods of type A carbonate apatite completely substituted by carbonate ions have not been established, which is disadvantage of the application for designing biomaterials.…”