Stage 1
The actual tendency in the domain of the advanced implant biomaterials was evaluated: the development of new alloys with non-toxic alloying elements (Nb, Zr, Ta) and good mechanical compatibility (high mechanical resistance, ductility, wear, fatigue and low elastic modulus very closed with that of the bone. For this project the new alloy Ti-Zr-Nb alloy was selected to assure a low Yioung's modulus and high corrosion resistance.
The problem of the controlled processing of the bioalloy surfaces evidenced the main methods used in present: physical, chemical and electrochemical methods. The advantages and drawbacks of these methods were studied.
The characterisation of the processed surfaces will be made by electrochemical, microscopically and spectroscopic methods.
The following electrochemical methods were selected: cyclic voltammetry (for the determination of the main electrochemical parameters); linear polarisation (for the obtaining of the corrosion rates); electrochemical impedance spectroscopy - EIS (for the obtaining of the impedance spectra and for the elaboration of the electric equivalent circuits); in time variation of the open circuit potentials and of the corresponding open circuit gradients (for the monitoring of the long-term behaviour and of the susceptibility to local and galvanic corrosion).
The following microscopic methods for the characterization of the processed surfaces were selected: scanning electron microscopy -SEM (surface topographical analysis, composition profile, crystalline structure and its orientation in space, details of the crystalline network, impurities, growth defects, vacancies, inclusions, fissures, dislocations, atom distribution at the grain boundary), electronic dispersive spectroscopy -EDS (identify the compounds on the surface), atomic force microscopy -AFM (three-dimensional topography, rugosity), Raman spectroscopy -RS (for the species present in the coating composition, molecular structure and non-polar bondings).
The following spectroscopic methods for the characterization of the processed surfaces were selected: X-Ray photoelectronic spectroscopy - XPS (structure and energetic levels of the species, of oxides and of surface compounds); Fourier transform infrared spectroscopy - FT-IR (chemical bondings, molecular structure, compound identification, electronic and vibration states, the length of the chemical bonds); X-ray diffraction -XRD (analysis of the crystalline structure, of the distance between the junction of the crystalline network).
The electrochemical methods are: anodisation with current source (the surface oxidation and the formation of the hydroxyapatite or of its some precursor, varying the main electrodeposition parameters) and cathodic potentiostatic electrodeposition (direct electrodeposition of hydroxyapatite, controlling the process parameters).
The chemical methods take into consideration the individual and/or sequential processing by different hydrothermal procedures in solutions having in view the obtaining of: optimal structure with functional groups, controlled porosity and rugosity.
The bacteriostatic method consists of the application of non-toxic oxides but with antibacterial activity by the sono-chemical method; the high intensity sonic waves or ultrasonic waves will produce cavities into the metallic substrate and by collision will introduce antibacterial nanoparticles in the substrate, assuring a powerful anchorage of the bacteriostatic nanoparticles to the surface.
Stage 2
The conceptual procedure for the electrochemical processing of the new Ti-Zr-Nb bioalloy surface by the method of the electrochemical anodic galvanostatic polarisation at high current and voltage that forms a thick compact film of protective oxides was elaborated.
SEM studies showed that the obtained coating has o structure with nanotubes very favourable for the cell adhesion and proliferation.
The experiment for the method of the controlled processing of new Ti-Zr-Nb bioalloy surface took into consideration the determination of the corrosion resistance of this alloy in comparison with un-covered alloy using the electrochemical method of the cyclic potentiodynamic and linear polarisation and the monitoring of the open circuit potentials and of the corresponding open circuit gradients. Ringer solutions and Carter-Brugirard artificial saliva of different pH values were used to simulate the severe functional conditions of an implant.
Corrosion resistance of the electrochemical processed bioalloy in Ringer solutions evidenced a nobler behaviour of the processed bioalloy than that of the un-processed one, indicating that the electrochemical processed alloy passivated easier, more rapid as result of the existence of the electrodeposited layer that improves the protective properties of the native passive layer by its thickening. The main corrosion parameters have better values for the electrochemical covered alloy than for that un-covered, proving a more resistant passive layer.
Corrosion resistance of the electrochemical processed bioalloy in artificial Carter-Brugirard saliva show a better behaviour of the processed alloy than of the un-processed one due to the beneficial effect of the electrochemical processing. In doped saliva, slightly unfavourable values resulted but the alloy remained in the passive, resistant state on the whole studied potential domain. The best electrochemical parameters were registered for the processed alloy in neutral Carter-Brugirard saliva.
The modelling of the interface between bioalloy with processed and un-processed surface / human fluids was realised with the method of the electrochemical impedance spectroscopy (EIS); the interpretation of the Nyquist and Bode spectra permitted the formulation of the models for the alloy passivation process by equivalent electric circuits.
The modelling of the interface in Ringer solutions revealed a better behaviour of the processed alloy than that of the un-processed one. The film is formed by an inner, barrier layer and an outer porous layer. An electric equivalent circuit with two time constants was modelled: the first time constant illustrates the inner, barrier layer and the second time constant refers to the outer porous layer.
The modelling of the interface in artificial Carter-Brugirard saliva by impedance spectra revealed a thicker, resistant passive film for the covered alloy than for the un-covered one.
The human osteoblast and fibroblast cell adhesion and proliferation was analysed after 48 h, 96 h and 144 h of culture; the cell proliferation intensified on the processed alloy surface in comparison with un-processed alloy surface; the toxicity was zero for the both surfaces.
Stage 3
Green chemical method adapted to the specifical composition of Ti-15Nb-5Zr alloy conducted to the formation of a hydroxyapatite (HA) nanolayer on its surface.
SEM, AFM and XPS analyses showed that on the Ti-15Nb-5Zr alloy surface was deposited crystalline hydroxyapatite with important roughness; these qualities confer good bioactivity and osseointegration capacity to coating.
Electrochemical studies evinced a nobler behaviour of the covered alloy in comparison with bare one, by the nobler values of the corrosion and passivity potentials, more reduced values of the tendency to passivation and passive current density due to the protective, passive effect of the HA nanolayer deposited on the alloy surface.
Modelling of the bioalloy with nanostructured surface / simulated biological fluids interface indicates an insulating coating formed from two layers: a very compact, resistant layer represented by the native oxide passive film and a porous layer formed by the hydroxyapatite chemically deposited.
Corrosion resistance of the obtained coating demonstrate that for the coated alloy, corrosion current rate and total quantity of ions released into biofluids have values of 20 times lower than those of bare one, denoting better protective, barrier properties of the HA coating. Polarisation resistance that characterise the passive layer reaches values of M , namely, the coating is very insulating and very resistant.
Sonochemical method was designed and experimented. The proposed concept is new, does not exist on the commercial level and was realised at the laboratory level; it is a sonochemical process in a single stage assuring a long-term antibacterial protection.
Characterisation of the antibacterial coatings with original compositions (patentable), obtained by sonochemical method revealed uniform depositions of antibacterial nanoparticles (confirmed by XPS and SEM analysis) with typical dimensions 10 - 20 nm.
Surplus objective. An original composition Ti-15Zr-10Nb was established and the alloy has innovative properties: superior workability, mechanical properties and corrosion resistance suitable for a good implant material. Complete and complex characterisation regarding the microstructure, mechanical properties, electrochemical and corrosion behaviour in simulated biofluids for long-term was realised.
Dissemination
Scientific papers
1. J.M. Calderon Moreno, C. Vasilescu, S.I. Drob, M. Popa, P. Drob, E. Vasilescu, Electrodeposition, characterization and corrosion stability of nanostructured anodic oxides on new Ti-15Zr-5Nb alloy surface, J. Nanomater, 2013 ID 858935, 11 pages, impact factor 1,547 (2012)
2. J.M. Calderon Moreno, E. Vasilescu, P. Drob, C. Vasilescu, S.I. Drob, M. Popa, Surface and electrochemical characterization of a new ternary titanium based alloy behaviour in biofluids simulating severe conditions from the human body, Corros. Sci. 77, 52-63, 2013, impact factor 3,615 (2012)
3. J.M. Calderon Moreno, C. Vasilescu, S.I. Drob, E.I. Neacsu, M. Popa, Evaluation of the microstructural, mechanical and corrosion properties of a new ternary Ti-15Zr-5Nb alloy in simulated oral environment, Mater. Corros., DOI: 10.1002/maco.201307053, impact factor 1,208 (2012)
4. J.M. Calderon Moreno, C. Vasilescu, S.I. Drob, S. Ivanescu, P. Osiceanu, P. Drob, M. Popa, S. Preda, E. Vasilescu, Surface and electrochemical characterisation, microstructural and mechanical properties of a new Ti-Zr-Nb alloy for implant applications, manuscript submitted to ISI journal.
5. C. Vasilescu, S. I. Drob, P. Osiceanu, M. Anastasescu, J.M. Calderon Moreno, Chemical deposition and characterisation of bioactive coating on new ternary alloy surface, manuscript under preparation.
6. S.I. Drob, C. Vasilescu, P. Osiceanu, J.M. Calderon Moreno, Characterisation of new anodic oxidized titanium base alloy for dental applications, manuscript under preparation.
Scientific communications
1. J. M. Calderon Moreno, M. Popa, N. Stanica, Synthesis, structure and magnetic behavior of single-phase BiFeO3 powders from a polymeric precursor, 2nd International Advances in Applied Physics & Materials Science Congress, 26-29 April 2012, Antalya, Turkey, paper No 248.
2. M. Popa, E. Vasilescu, P. Drob, J. M. Calderon Moreno, C. Vasilescu, S. I. Drob, Electrochemical characterisation of a new advanced implant alloy in simulated physiological fluids, 2nd International Advances in Applied Physics & Materials Science Congress, 26-29 April 2012, Antalya, Turkey, paper no 184.
3. J. M. Calderon Moreno, M. Popa, C. Vasilescu, S. I. Drob, Characterization of mechanical and anticorrosive properties of a new titanium based alloy, 3rd International Advances in Applied Physics & Materials Science Congress, 24-28 April 2013, Antalya, Turkey, paper No. 134.
Stage 4
Evaluation and optimization of new chemical coating methods: morphological and structural stability over time, corrosion resistance in simulated physiological solutions of different pH values (7.58, 8.91), especially the susceptibility to localized or galvanic corrosion .
Monitoring by periodic morpho-structural analysis of coating morphology and microstructure (SEM) and its composition (EDX) .
After 500 hours of immersion in neutral and alkaline Ringer solution, the entire surface is coated, additional spherical formations being deposited; acting as nuclei for growth of bone cells, favoring metallic implant anchorage to human bone, therefore the coating is bioactive.
EDX spectra show the presence of phosphorus and calcium in large amounts on the surface, as well as oxygen, the main components of HA .
Assessment of the susceptibility to localized and galvanic corrosion from the variation in time of the open circuit potential, and of the open circuit potential gradients.
Open circuit potentials moves in time toward more electropositive values due to growth and thickening of the film on the surface; the HA coating has superior protective properties and provides long-term stability.
Galvanic corrosion does not occur even for the long-term (500 h) on the alloy coated with HA.
Evaluation and optimization of bacteriostatic ZnO nanocoatings was performed by long-term monitoring (500 hours of immersion in Ringer solution) of the morphology, structure, corrosion resistance and electrochemical behaviour in severe operating conditions.
SEM images showed a stable microstructure with ZnO nanoparticles sized below 30 nm. EDX spectrum detected the presence of Zn lines with lower intensities than the as-deposited original coating, namely, the ZnO nanoparticles were partly dissolved in physiological solutions, thus acting as antibacterial factor.
Monitoring the corrosion resistance of the bacteriostatic coating show an improvement of the values for all corrosion parameters for the processed antibacterial alloy due to the effect of ZnO antibacterial coating to inhibite the alloy corrosion by reducing the effective active areas on the alloy surface, acting as an effective passive layer .
The decrease in the corrosion current, corrosion rate, ion release and the increase of the polarization resistance indicates the increase of corrosion resistance over time.
Monitoring of the alloy behaviour processed with ZnO highlights a nobler behaviour of the processed alloy, proven by more favourable values of the main electrochemical parameters.
Sonochemical ZnO nanoparticles deposited on the surface of the alloy Ti-15Zr-5Nb substantially increased the corrosion resistance of the alloy, maintaining and improving over time the resistance of the alloy, confering a nobler behaviour guaranteed for 500 hours till now.
Original results
- Original contributions on the long-term morpho- structural evolution (by SEM and EDX methods) of hydroxyapatite (HA) coating deposited by green chemistry method on the surface of the new alloy Ti-15Zr-5Nb
- Demonstration of the long-term stability of HA nanocoating (SEM and EDX)
- Scientific novelties on the evolution in time of the morphology and structure of ZnO bacteriostatic coatings deposited by an original sonochemical method on the surface of the alloy Ti-15Zr-5Nb
- Bank of original data on long-term corrosion resistance of the antibacterial processed alloy Ti-15Zr-5Nb
- Innovative electrochemical properties of the alloy Ti-15Zr-Nb with the antibacterial surface functionalized sonochemically with ZnO nanoparticles
Dissemination
ISI Articles
1. C. Vasilescu, M. Popa, S. I. Drob, P. Osiceanu, M. Anastasescu, J. M. Calderon Moreno, Deposition and characterization of bioactive ceramic hydroxyapatite coating on surface of Ti-15Zr-5Nb alloy, Ceram. Int., 40 (9 Part B), 14973-14982, 2014, indice impact 2,086 (2013)
2. J. M. Calderon Moreno, C. Vasilescu, S. I. Drob, S. Ivanescu, P. Osiceanu, P. Drob, M. Popa, S. Preda, E. Vasilescu, Microstructural and mechanical properties, surface and electrochemical characterisation of a new Ti-Zr-Nb alloy for implant applications, J. Alloy Compd., 612, 398-410, 2014, indice impact 2,726 (2013)
3. J. M. Calderon Moreno, C. Vasilescu, S. I. Drob, E. I. Neacsu, M. Popa, Evaluation of the microstructural, mechanical and anti-corrosive properties of a new ternary Ti-15Zr-5Nb alloy in simulated oral environment, Mater. Corros., 65 (7), 703-714, 2014, indice impact 1,508 (2013)
Articles in Proceedings
1. J. M. Calderon Moreno, P. Drob, C. Vasilescu, S. I. Drob, M. Popa, E. Vasilescu, Oxide nanolayers grown on new ternary Ti based alloy surface by galvanic anodizing - characteristics and anticorrosive properties, Proceedings of 19th International Corrosion Congress, 2014, Ed. International Corrosion Council, USA, P-17, 1-9.
Stage 5
In vitro studies for short and long term showed that the un-treated Ti-15Zr5Nb alloy and the same alloy subjected to chemical treatment can be successfully used for bone implants, the treated alloy presenting a better osteoconductive activity.
From the cyclic potentiodynamic polarization curves for Ti-15Zr5Nb alloy covered with hydroxyapatite (HA) resulted more favourable in time values for the all electrochemical parameters, namely, the alloy passivity is better due to HA layer that thickened, compacted over time.
The main corrosion parameters, corrosion current densities and corrosion rates decreased in time, fact that signify the thickening of the coating and the increasing of its corrosion resistance; polarization resistances have very high values, order of M , values that increase in time, namely, the deposited layer improves its insulating, protective properties by the incorporation of calcium and phosphor ions from the solution.
Nyquist impedance spectra as capacitive semicircles have bigger values of their curvature radii in time, indicating the thickening of the HA coating, the improvement of its stability and corrosion resistance.
Bode impedance spectra for the HA covered Ti-15Zr5Nb alloy evince three phase angles: the higher phase angle characterize the barrier layer and the lower phase angle, the porous layer, the both layers belonging to the passive film; the three phase angle, with the lowest value indicates the porous HA layer where take place diffusion and deposition processes of ions or compounds from the solution, which thickened over time the initial HA deposition. The values of those three phase angles increase in time, that meaning that the thickening both of the passive film and of the HA coating.
An electric equivalent circuit containing three time constants was modelled: the first time constant signifies the barrier layer of the passive film; the second time constant represents the porous layer of the passive film; the third time constant identifies tha porous layer of HA.
The electrical parameters of the fitted equivalent circuit improve their values in time, both in neutral and alkaline Ringer solution: the resistances of the passive film have higher values in time, namely, this film becomes more resistant; the resistance of the HA coating has lower values than the other resistances, due to its porous character; the slow over time increase of the HA layer resistance show the thickening of the coating, this remaining porous, susceptible to interact with the humanfluid. In time variation of the capacities denotes a more resistan passive film and a more porous HA layer.
Original results
- Original contributions regarding the determination of in vitro biocompatibility of the Ti-15Zr5Nb alloy surface processed by chemical method.
- Scientific novelties referring to the long term stability of the chemical processed surface, from the electrochemical studies.
- The demonstration of the over time thickening both of the passive film and of the HA coating.
- Original data bank related to the long term monitoring of the main electrochemical and corrosion parameters.
- Original scientific results on the in time variation of the electrical parameters for the electric equivalent circuit.
Disemination
ISI Articles
1. M. Popa, C. Vasilescu, S.I. Drob, J. Hmeljak, A. Coer, J.M. Calderon Moreno, Long-term corrosion behaviour and biocompatibility testing of titanium based alloy covered with nano-crystalline hydroxyapatite, Mater. Corros. 66(6) 562-572, 2015. impact factor 1,373 (2014)
Scientific communications
1. M. Popa, C. Vasilescu, S. I. Drob, P. Osiceanu, M. Anastasescu, J. M. Calderon Moreno, Characterisation and stability of ceramic biomimetic nanolayers obtained on surface of a new bioalloy, XXII International Symposium on Bioelectrochemistry and Bioenergetics, 2015, Malmo, Sweden, s3-018.
2. J. M. Calderon Moreno, S. I. Drob, C. Vasilescu, P. Osiceanu, E. Vasilescu, Deposition and properties of bacteriostatic nanocoating by sonochemical method, XXII International Symposium on Bioelectrochemistry and Bioenergetics, 2015, Malmo, Sweden, s3-017.
3. M. Popa, C. Vasilescu, S. I. Drob, J. M. Calderon Moreno, Characterization of bioactive hydroxyapatite coating on ternary Ti-Zr-Nb alloy surface, EUROCORR 2015, European Corrosion Congress, Graz, Austria, p. 86..
4. J. M. Calderon Moreno, C. Vasilescu, S. I. Drob, M. Popa, Corrosion modeling of a new Ti-Zr-Nb alloy in Ringer's solutions simulating severe functional conditions, EUROCORR 2015, European Corrosion Congress, Graz, Austria, p. 40.
Stage 6
The biocompatibility and antibacterial properties of bare and coated Ti-15Zr-5Nb alloys were evaluated.
Determination of bacteriostatic properties focused on the analysis of the effectiveness of the obtained antimicrobial surfaces containing antibacterial agent (ZnO), on the alloy Ti-15Zr-5NB. The coated alloy exhibited a strong antibacterial biofilm activity .
The nanostructured anti-biofilm coating of ZnO has been tested against Gram-positive and Gram-negative bacteria, which are known for their ability to grow as biofilms on implants: S. aureus ATCC 6538, E. faecalis ATCC 29212 and E. coli ATCC 8739. The ability of bacterial growth inhibition was demonstrated against S. aureus and E. faecalis biofilms after 6 h and against E. coli biofilm after just 1 hour contact.
Determination of biocompatibility include the analysis of toxicity of the alloys on MC3T3-E1 cells, the analysis of cell viability and proliferation, assessment of cell adhesion and morphology and evaluation of cell differentiation after 3 and 6 weeks.
The coated alloy demonstrated good biocompatibility and cell response, promoted the proliferation of MC3T3-E1 preosteoblasts. Furthermore, a higher potential to induce extracellular matrix mineralization was displayed in comparison to the bare alloy.
The ability to inhibit corrosion of the metal substrate in biofluid has been demonstrated by the improvement of all the corrosion parameter values for the alloy processed with antibacterial coating compared to the unprocessed alloy; this is due to the corrosion inhibition effect of the ZnO nanostructured coating, acting effectively as a passive layer by reducing the effective active areas on the surface of the alloy.
Long-term monitoring of the electrochemical behavior (1000h) of the antibacterial surface showed that electrochemical parameters for the antibacterial protected alloy decreased very little with time, implying that the process of dissolution of ZnO nanoparticles occurs slowly. All electrochemical parameters for the unprocessed alloy present worse values than the values for the protected antibacterial alloy surface, which indicates a nobler electrochemical behavior of the antibacterial protected alloy.
For evaluation and optimization of the three coating methods (electrochemical anodization, HA coating by green chemical method, antibacterial ZnO coating by sonochemical deposition), a database on the protective capacity of functionalized surfaces was developed which allows specialists in biomaterials appreciate and compare anticorrosive performance of the new alloy Ti-15Zr-5NB compared to other alloy implants.
Altogether, these findings indicate that the ZnO coated Ti-15Zr-5Nb alloy represents a promising alloy for use in orthopedic implants, with both good biocompatibility and good antibacterial properties, showing improved resistance to microbial colonization and long-term corrosion resistance.
Disemination
Patent A / 00055/ 26.01.2016
Sonochemical procedure for antibacterial nano-coating applied on the new ternary Ti alloy surface with application in orthopaedic implantology, J. M. Calderon Moreno, M. Popa, C. Vasilescu, S. I. Drob, A. Cimpean, V. Mitran
ISI Articles
J. M. Calderon Moreno, C. Vasilescu, S. I. Drob, P. Osiceanu, V. Mitran, A. Cimpean, G. G Parcalabioru, M. C. Chifiriuc, M. Popa,. ZnO coating of Ti-5Zr-5Nb alloy, antibiofilm activity, cell response and corrosion resistance in simulated body fluid, submitted for publication.
Scientific communications
1. S. I. Drob, J. M. Calderon Moreno, C. Vasilescu, P. Osiceanu, M. Anastasescu, M. Popa, Chemical treatment of new Ti-Zr-Nb alloy surface by applying hydroxyapatite coating, 19th Topical Meeting of the International Society of Electrochemistry, 17-20 April 2016, Auckland, New Zealand, s1-017.
2. J. M. Calderon Moreno, S. I. Drob, C. Vasilescu, P. Osiceanu, M. Popa, E. Vasilescu, Deposition and properties of bacteriostatic nanocoating by sonochemical method, 6th Baltic electrochemistry Conference, Helsinki, 15th - 17th June 2016, , Book of Abstract, p. 60.
3. M. Popa, C. Vasilescu, S. I. Drob, P. Osiceanu, M. Anastasescu, E. Vasilescu, J. M. Calderon Moreno, Characterisation and stability of ceramic biomimetic nanolayers obtained on the surface of a new bioalloy, 6th Baltic electrochemistry Conference, Helsinki, 15th - 17th June 2016, Book of Abstract, p. 81.
4. J.M. Calderon Moreno, S.I. Drob, C. Vasilescu, P. Osiceanu, M. Popa, E. Vasilescu, Deposition and properties of bacterioastatic nanocoating by sonochemical method, 13th International Conference on Nanosciences & Nanotechnologies, NN 16, 5-8 July 2016, Thessaloniki, Greece, Book of Abstracts, p. 138.
5. M. Popa, C. Vasilescu, S.I. Drob, P. Osiceanu, M. Anastasescu, J.M. Calderon Moreno, Characterisation and stability of ceramic biomimetic nanolayers on the surface of a new bioalloy, 13th International Conference on Nanosciences & Nanotechnologies, NN 16, 5-8 July 2016, Thessaloniki, Greece, Book of Abstracts, p. 137.
6. J. M. Calderon Moreno, S. I. Drob, C. Vasilescu, E. Vasilescu, P. Osiceanu, M. Popa, In-situ Sonochemical Synthesis and Deposition of Bacteriostatic ZnO Nanocrystallite Coatings for Biological/Medical Applications, 2nd Zing Nanocrystals Conference, 2-5 August Dublin, Irlanda, Book of Abstracts, p 37.
7. M. Popa, C. Vasilescu, S. I. Drob, P. Osiceanu, M. Anastasescu, E. Vasilescu, J. M. Calderon Moreno, Deposition of Ceramic Biomimetic Nanocrystal Layer on a New Biomedical Alloy Surface, 2nd Zing Nanocrystals Conference, 2-5 August Dublin, Irlanda, Book of Abstracts, p 36.
8. J.M. Calderon-Moreno, C. Vasilescu, S. I. Drob, S. Ivanescu, P. Osiceanu, M. Popa, S. Preda, E. Vasilescu, Characterization of a new Ti-Zr-Nb alloy for implant applications, ROMPHYSCHEM 16, 21-23 Sept. Galati, Book of Abstracts, p. 26
Original results
- Sonochemical deposition of ZnO antibacterial coatings for the first time on a biomedical alloy, the new alloy Ti-15Zr-5Nb.
- Scientific contributions on the ability of inhibition of both bacterial growth and corrosion of the metal substrate in biofluids.
- Monitoring of the long term (1000 h) electrochemical behavior of the alloy Ti-15Zr- 5Nb with antibacterial coating.
- Modeling of the interface uncoated or coated alloy / biofluid.
- Original databank on the protecting capacity of the Ti-15Zr- 5Nb alloy coated with (a) titanium oxide by electrochemical method, (b) hydroxyapatite by green chemical method, (c) ZnO antibacterial coating using a sonochemical method.
