Effect of surface modification on the corrosion resistance of Zr 2.5Nb as material for permanent implants

Zirconium is a potential material for permanent implants. In particular, surface modification induced by anodisation has proved to be effective to improve corrosion resistance while keeping good osseointegration. The combination of zirconium with niobium is supposed to develop a structure that presents a high corrosion resistance and continues having the mechanical resistance necessary for implants. The aim of the present work is to determine the viability of using anodised Zr-2.5Nb as implant material, and compare it with pure Zr. Electrochemical tests performed in the anodizing solution and in a simulated biological solution revealed that by anodising the materials a higher corrosion resistance is obtained. The improvement on the corrosion resistance is particularly noticeable in the case of the pure metal after a short period immersed in the simulated biological solution. But, after a long period of immersion, the alloy shows better performance.Fil: Farina, Silvia Beatriz. Universidad Nacional de San Martín; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Unidad de Actividad de Materiales (CAC); ArgentinaFil: Gomez Sanchez, Andrea Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Ceré, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Hybrid Epoxy-Alkyl Sol–Gel Coatings Reinforced with SiO2 Nanoparticles for Corrosion Protection of Anodized AZ31B Mg Alloy

AZ31B Mg alloys were anodized at different potentials using an alkaline electrolyte. Then, an epoxy-alkyl silane sol reinforced with SiO2 nanoparticles was prepared by sol–gel and deposited on top of the optimized anodic layers. 1-Methyl imidazole was added to the sol to promote a partial epoxy ring aperture and improve the condensation degree of the inorganic network. The results showed the curing temperature affects the inorganic polycondensation of the organic-inorganic network; this effect was analyzed by29 Si and13 C solid-state NMR spectroscopy. Electrochemical impedance spectroscopy in 3.5 wt% NaCl solution revealed that the corrosion resistance is enhanced by the anodized process obtained for Mg alloy anodized at 100 V/2 min. However, a quick deteri-oration of the oxide film with immersion time was evident, showing a reduction of the protection efficiency (ηE%) of 76.5% after 16 h/immersion. The deposition of an epoxy-alkyl coating improved the ηE% up to 98.6% after 72 h/immersion. The proposed hybrid coating used for post-sealing the porous anodized Mg alloy looks like a good alternative protective barrier to control the corrosion process of Mg alloys. A suitable compromise between cross-linking network and curing temperature is necessary to obtain a good barrier coating.Fil: Merino, Emilia. Consejo Superior de Investigaciones Científicas; España. Instituto de Cerámica y Vidrio de Madrid; EspañaFil: Durán, Alicia. Consejo Superior de Investigaciones Científicas; España. Instituto de Cerámica y Vidrio de Madrid; EspañaFil: Ceré, Silvia. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Castro, Yolanda. Instituto de Cerámica y Vidrio de Madrid; España. Consejo Superior de Investigaciones Científicas; Españ

Hybrid sol-gel coatings containing clay nanoparticles for corrosion protection of mild steel

The development of a new environment-friendly anticorrosive coating for mild steel substrate is afforded in this work. The combined use of cerium, as a self-healing agent, and clay nanoparticles, as improvers of the barrier properties, was considered to the development of new anticorrosive sol-gel coatings. Nanostructured hybrid films were synthesized by the sol-gel route from tetraethoxysilane (TEOS) and 3-glicidoxipropyl-trimetoxisilano (GPTMS) using laminar nanoclays (Laponite Na+0.7[Si8Mg5.5Li0.3H4O24]−0.7) to improve mechanical and barrier properties, and Ce(NO3)3?6H2O as a supplier of Ce(III) to provide an inhibiting effect in the event of coating failure. Carbon steel plates, AISI 1010, were used as substrates. Prior to the application of the coating, samples were treated with a phosphoric acid 2% v/v in order to improve coating adherence.In order to evaluate cerium effect, electrochemical behaviour of films containing Laponite and cerium salts (TGL-Ce) were compared with films containing only Laponite (TGL) by means of potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) measurements using a 0.35 wt% NaCl solution. Microstructural characterization and surface analysis of substrates and sol-gel coatings were performed by optical microscopy and by XPS techniques. The use of nanoclays allowed to achieve a significant improvement of the anticorrosive behaviour of the cerium doped coating at the same time that enhances the physical integrity of the coatings under immersion tests.Fil: Santana, Ianina Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Pepe, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Schreiner, Wido H.. Universidade Federal do Paraná; BrasilFil: Pellice, Sergio Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Ceré, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Effect of anodization on the surface characteristics and electrochemical behaviour of zirconium in artificial saliva

The paper is focused on elaboration of ZrO2 films on pure zirconium via anodizing inphosphoric acid with and without fluoride at constant potentials of 30 V and 60 V. Thestructure and composition of the films were investigated using scanning electronicmicroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The composition ofthe oxides formed at both potentials can be identified as monoclinic ZrO2. In addition to Zrand O, the layers formed in phosphoric acid contain phosphorus originating from thephosphoric acid. When the phosphoric acid solution contains NaF, fluorine is alsoincorporated into the oxide layer. The oxides formed at a higher voltage have greaterroughness than those formed at 30 V. Anodized samples exhibit smaller current densitiesduring anodic polarization compared to the as-received zirconium covered with native oxide.Fil: Romonti, Daniela E.. Faculty of Applied Chemistry and Materials Science; RumaniaFil: Gomez Sanchez, Andrea Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Milošev, Ingrid. Jožef Stefan Institute; EsloveniaFil: Demetrescu, Ioana. Faculty of Applied Chemistry and Materials Science; RumaniaFil: Ceré, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Effect of anodized zirconium implants on early osseointegration process in adult rats: a histological and histomorphometric study

Since surface plays a key role in bioactivity, the response of the host to the biomaterial will determine the success or failure of the prosthesis. The purpose of this study is to make an exhaustive analysis of the histological and histochemical characteristics of new bone tissue around Zr implants anodized at 60 V (Zr60) supported by histomorphometric methods in a rat model. Fibrous tissue was observed around the control implants (Zr0) and osteoblasts were identifed on the trabeculae close to the implantation site that showed typical cytological characteristics of active secretory cells, regardless of the surface condition. The histomorphometrical analysis revealed a signifcant increase in cancellous bone volume, trabecular thickness and in trabecular number together with a decrease in trabecular separation facing Zr60. TRAP staining showed that there was a relative increase in the number of osteoclasts for Zr60. In addition, a larger number of osteoclast with a greater number of nuclei were detected in the tibiae for Zr60. This research demonstrated that the new bone microarchitecture in contact with Zr60 is able to improve the early stages of the osseointegration process and consequently the primary stability of implants which is a crucial factor to reduce recovery time for patients.Fil: Tano de la Hoz, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Katunar, Maria Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Gonzalez, Ariel. Universidad Nacional de Mar del Plata; ArgentinaFil: Gomez Sanchez, Andrea Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones y Transferencia de Villa María. Universidad Nacional de Villa María. Centro de Investigaciones y Transferencia de Villa María; Argentina. Universidad Tecnologica Nacional. Facultad Regional Villa Maria; ArgentinaFil: Díaz, Alcira Ofelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Ceré, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Electrochemical characterization of AISI 316L stainless steel in contact with simulated body fluid under infection conditions

Titanium and cobalt alloys, as well as some stainless steels, are among the most frequently used materials in orthopaedic surgery. In industrialized countries, stainless steel devices are used only for temporary implants due to their lower corrosion resistance in physiologic media when compared to other alloys. However, due to economical reasons, the use of stainless steel alloys for permanent implants is very common in developing countries. The implantation of foreign bodies is sometimes necessary in the modern medical practice. However, the complex interactions between the host and the can implant weaken the local immune system, increasing the risk of infections. Therefore, it is necessary to further study these materials as well as the characteristics of the superficial film formed in physiologic media in infection conditions in order to control their potential toxicity due to the release of metallic ions in the human body. This work presents a study of the superficial composition and the corrosion resistance of AISI 316L stainless steel and the influence of its main alloying elements when they are exposed to an acidic solution that simulates the change of pH that occurs when an infection develops. Aerated simulated body fluid (SBF) was employed as working solution at 37°C. The pH was adjusted to 7.25 and 4 in order to reproduce normal body and disease state respectively. Corrosion resistance was measured by means of electrochemical impedance spectroscopy (EIS) and anodic polarization curves.Fil: López, Damián Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Durán, Alicia. Instituto de Ceramica y Vidrio de Madrid; EspañaFil: Ceré, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Sol-gel coatings for protection and biofunctionalization of stainless-steel prosthetic intracorporeal devices in Latin-America

Latin-American researchers, collaborating with the international community, have contributed in the last decades to sol-gel knowledge related to the generation of coatings on metallic bioimplants. Sol-gel technology allows the formation of relatively thin (1–2 microns) adherent, flexible and compact coatings that can be used as protection against corrosive media and for post-functionalization. Regarding low carbon surgical grade stainless steel, the application of silica-based sol-gel coatings with different types of reinforcement and incorporating bioactive or antibacterial particles as a second phase, generates promising corrosion protection properties within physiological environments. In addition, they can prevent infections and stimulate bone formation/growth. This work explores the corrosion protection features provided by thin functionalized silica sol gel coatings to be used in orthopaedic devices.Fil: Ballarre, Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Ceré, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Bioactive coatings deposited on titanium alloys

One of the ways to minimise corrosion products release from metallic implants to the surrounding tissue consists in applying a protective coating which may be functionalised with a bioactive material, able to generate a natural bonding to the living tissue. This work describes the development of a double layer coating obtained by the sol-gel technique containing bioactive glass, glass-ceramic or hydroxyapatite particles in hybrid methyl-triethoxisilane (MTES) and tetraethilorthosilicate (TEOS) sol on titanium alloy (ASTM F 67). Samples were electrochemically evaluated in a simulated body fluid (SBF). The application of the coating on the titanium alloy shows an improvement in the corrosion resistance in the tested period of time. This improvement could be due to the reaction of the particles with the physiological medium, which nucleates the formation of calcium phosphate crystals, and blocks the porosity of the coating.Fil: García, C.. Universidad Nacional de Colombia; ColombiaFil: Ceré, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Durán, A.. Instituto de Ceramica y Vidrio de Madrid; Españ

Oxygen reduction on Cu–Zn alloys

The reduction of oxygen on brass type Cu77Zn21Al2 in contact with 0.1 mol L-1 borax at pH 9.2 with and without chlorides was investigated and compared with the results on spectroscopic Cu. The surface film was characterized in situ by means of reflectance spectroscopy and by electrochemical impedance in the potential range negative to the open circuit potential. The main parameters associated to the kinetics of the oxygen reduction reaction were analyzed with a rotating disc electrode. The results show that within the potentials studied, a porous film was formed on brass while no significant spectral features were observed, except at -1.2 V where zinc oxo-hydroxides grow in chloride-free solutions and dissolve when chlorides are present in the system. The number of electrons exchanged for brass was close to 4 in both solutions, showing that oxygen is predominantly reduced to hydroxyl ions, with a reaction order equal to one. The residual presence of oxides on the surface results in Koutecky-Levich plots with slopes dependent on the applied potential and interfere with the calculation of the Tafel slope.Fil: Procaccini, Raul Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Ceré, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Vazquez, Marcela Vivian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Caracterización de Películas Superficiales Sobre Aleaciones de Cobre: Influencia Sobre la Reducción de Oxígeno

La corrosión es un fenómeno de permanente interés e importancia tecnológica siempre vigente, por las pérdidas económicas que ocasiona, tanto directas como indirectas. Estudiando los procesos que participan de la corrosión de un material se contribuye a mantenerla bajo control. La reducción de oxígeno es la semi-reacción catódica dominante en medios acuosos aireados y su estudio reviste interés debido a la importancia de esta reacción en la tecnología de celdas de combustión y en la protección y deterioro de metales. La información relativa al mecanismo de esta reacción sobre metales corroíbles es escasa. Este trabajo apunta a investigar la reducción de oxígeno en soluciones de buffer bórico - borato de sodio pH 7.7 aireado sobre aleaciones de cuproníqueles UNS 720 y UNS 706 y cobre puro. Se propone avanzar en la investigación de la relación entre la composición de la aleación y la cinética de la reacción de reducción sobre materiales pre-reducidos y oxidados en condiciones controladas. Se estudian las composiciones características de las películas pasivas formadas in situ sobre los diversos materiales bajo estudio en soluciones aireadas en condiciones de potencial controlado mediante la técnica de espectroscopía de reflectancia diferencial. Se utilizan además otras técnicas electroquímicas experimentales de aplicación in situ que incluyen, voltametrías y técnicas hidrodinámicas como electrodo de disco rotante para caracterizar los parámetros cinéticos de la reacción de reducción de oxígeno.Corrosion phenomena are of permanent interest and of technological importance due to the direct and indirect economic losses it conveys. Studying the processes that participate in the corrosion of a material contributes in keeping it under control. Oxygen reduction is the dominant cathodic reaction in aerated aqueous media. The mechanism of this reaction is interesting to study because of the importance of this reaction in the technology of fuel cells and in the protection of materials. Information on the mechanism of this reaction on corrodible metals is scarce. In this work, oxygen reduction on copper and copper-nickel alloys UNS 72000 and UNS 70600 in aerated borax-borate buffer solution of pH 7.7 is investigated. The goal is to advance in the investigation of the relationship between alloy composition and the kinetics of the reduction reaction on pre-reduced and oxidized materials under potentiostatic control. The compositions of the passive films formed in situ on the different materials in controlled conditions are studied using differential reflectance spectroscopy. Other in situ techniques that include voltammetry and electrochemical hydrodynamic techniques such as rotating disc are used to characterize the kinetic parameters of the oxygen reduction reaction.Fil: Brizuela, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Ceré, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Vazquez, Marcela Vivian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin