Article

Application of Magnetron Sputtering for Producing Bioactive Ceramic Coatings on Implant Materials

Shandong University School of Mechanical Engineering Shandong Jinan 250061 P.R. China
Bulletin of Materials Science (Impact Factor: 1.02). 11/2008; 31(6):877-884. DOI: 10.1007/s12034-008-0140-z

ABSTRACT

Radio frequency (RF) magnetron sputtering is a versatile deposition technique that can produce thin, uniform, dense calcium
phosphate coatings. In this paper, principle and character of magnetron sputtering is introduced, and development of the hydroxyapatite
and its composite coatings application is reviewed. In addition, influence of heat treatment on magnetron sputtered coatings
is discussed. The heat treated coatings have been shown to exhibit bioactive behaviour both in vivo and in vitro. At last, the future application of the bioactive ceramic coating deposited by magnetron sputtering is mentioned.

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    • "RF Sputtering of Ca/P glasses including pyrophosphates and hydroxyapatite have been explored by a number of authors from as early as 1993. RF sputtering has been found to be an appropriate coating method, producing uniform , thin coatings, with superior adhesion strengths [16] [17] [18] [19] [20]. Yamashita et al. produced a range of binary Ca/P glass coatings with Ca:P ratios of 1.67, 1.0 and 1.5 via sputtering, which were subsequently crystallised by heating to form thin film apatites of hydroxyapatite, pyrophosphate and tri-calcium phosphate [21]. "
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    ABSTRACT: Phosphate based glass (PBG) coatings of up to 2.6 μm thick have been applied by RF magnetron sputtering for their potential in promoting osseointegration and potential as ion delivery systems for biomaterials. The processing behaviour of PBG under ion bombardment have been investigated, notably the phenomena of preferential sputtering. The relative sputtering yields for the elements within quaternary and quinternary glass oxides have been found to be dependent upon the chemical bonding and momentum exchange interactions at the surface, subsurface layers of the target material. This led to preferential sputtering in the order, P < Fe < Ca < Mg < Na, based on the absolute changes from 6 target compositions to their respective coating compositions, showing a reduction in P2O5 and Fe2O3 of between 10.3-15.2, 0.2-0.6 mol% respectively and an increase in MgO, CaO, and Na2O of 4.8-6.0, 0.1-3.8, and 3.0-6.9 mol% respectively. The order primarily corresponded to the relative dissociation energies of the network modifying ions bound to oxygen of (818.0 or 1227.0 for Fe), 928.0 for Ca, 788.0 for Mg, and 257.0 kJ mol− 1 for Na. The deposition rates from targets T1-T6 varied between 1.59-1.93 nm min− 1 at a constant pressure of 1.05 Pa. Increasing the pressure from 0.28 to 1.87 Pa led to improved stoichiometric transfer from target to coating.
    No preview · Article · Jun 2015 · Thin Solid Films
    • "To prevent these drawbacks, the magnetron sputtering technique can be used, because it offers a flexible approach to surface improvement of metal implants. This technique facilitates the deposition of dense and well-adhered films with controlled elemental composition [19] by selecting appropriate values of the deposition parameters (discharge power, gas flow rate, working pressure, substrate temperature, deposition time, substrate bias voltage) [9]. In order to obtain HAP coatings with the best bioactivity properties it is required a good control of the morphology, surface roughness, and crystallinity of the coatings [9]. "
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    ABSTRACT: Hydroxyapatite (HAP) ceramics belong to a class of calcium phosphate-based materials, which have been widely used as coatings on titanium medical implants in order to improve bone fixation and thus to increase the lifetime of the implant. In this study, HAP coatings were deposited from pure HAP targets on Ti6Al4V substrates using the radio-frequency magnetron sputtering technique at substrate temperatures ranging from 400 to 800 °C. The surface morphology and the crystallographic structure of the films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion resistance of the coatings in saliva solution at 37 °C was evaluated by potentiodynamic polarization. Additionally, the human osteosarcoma cell line (MG-63) was used to test the biocompatibility of the coatings. The results showed that all of the coatings grown uniformly and that the increasing substrate temperature induced an increase in their crystallinity. Corrosion performance of the coatings was improved with the increase of the substrate temperature from 400 °C to 800 °C. Furthermore, all the coatings support the attachment and growth of the osteosarcoma cells with regard to the in vitro test findings.
    No preview · Article · May 2015 · Applied Surface Science
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    • "the same, has an open pore-like structure; a consequence of the competing anodising and acid solution processes [17] "
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    ABSTRACT: In this study, the fabrication and characterization of Al/Al2O3 nanotubular arrays on Ti-6Al-4V substrate were carried out. To this end, aluminum thin films were deposited as a first coating layer by direct current (DC) magnetron sputtering with the coating conditions of 300 W, 150 °C and 75 V substrate bias voltage. Al2O3 nanotube array as a second layer was grown on the Al layer by electrochemical anodisation at the constant potential of 20 V within different time periods in a electrolyte solution. For annealing the coated substrate, plasma treatment (PT) was utilized under various conditions to get the best adhesion strength of coating to the substrate. To characterize the coating layers, micro scratch test, Vickers hardness and field emission of scanning electron microscopy (FESEM) were used. Results showed that after the deposition of pure aluminum on the substrate the scratch length, load and failure point were 794.37 μm, 1100 mN and 411.43 μm, respectively. After PT, the best adhesion strength (2038 mN) was obtained at RF power of 60 W. With the increase of the RF power from 60 to 80 W, a reduction in adhesion strength was observed (1525.22 mN). From the microstructural point of view, a homogenous porous structure with an average pore size of 40-60 nm was formed after the anodisation for 10-45 min. During PT, the porous structure was converted to dense alumina layer when the RF power rose from 40 to 80 W. This led to an increase in hardness value from 2.7 to 3.4 GPa. Based on the obtained data, the RF power of 60 W was the optimum condition for plasma treatment of Al/Al2O3 nanotubular arrays on Ti-6Al-4V substrate.
    Full-text · Article · Dec 2014 · Applied Surface Science
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