Siloxane-poly(methyl methacrylate) (PMMA) hybrid was synthesized based on the sol-gel method and applied to Ti-6Al-4V through dip-coating. The structural feature of the hybrid was subjected to Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TG); its morphological properties were analyzed through scanning electron microscope (SEM), energy dispersive spectrometry (EDS), atomic force microscopy (AFM) and contact angle. The electrochemical behavior and corrosion resistance of both the hybrid coating and the uncoated substrate were investigated based on electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). Results showed homogeneous coating formation due to the rigid hybrid network formed during polymerization, hydrolysis and condensation reactions. This outcome suggested interaction between the organic (methyl methacrylate (MMA)) and inorganic (tetraethyl orthosilicate (TEOS)) phases, which was favored by the coupling agent (3-(trimethoxysilyl)propyl methacrylate (TMSM)). The S0M (PMMA-SiO2 hybrid Ti-6Al-4V coated alloy) film presented regular topography and adherence to the substrate. Electrochemical simulated body fluid (SBF) tests showed that the hybrid coating presented better barrier properties (168 h of the immersion time) than the uncoated substrate, fact that makes it an interesting material for anti-corrosive applications in biomaterials.

Los materiales híbridos a base de siloxano y PMMA se constituyen por una red de silicona, a la que están enlazadas cadenas de polimetilmetacrilato. Su estabilidad y adherencia permiten su aplicación en láminas de estaño para aumentar la resistencia a la corrosión. En este trabajo se recubrió una lámina de estaño con una película híbrida a partir de un sol que consta de los precursores alcóxidos: 3-trimetoxisililpropilmetacrilato (TMSM) y polimetilmetacrilado (PMMA). Se evaluó la influencia de la adición de tetraetoxisilano (TEOS). Se evaluó la morfología de los filmes por SEM y ángulo de contacto. Se evaluó el comportamiento electroquímico con medidas de potencial a circuito abierto, polarización potenciodinámica e impedancia electroquímica. Los resultados muestran que la película con mayor adición de TEOS tuvo mayor espesor; sin embargo, el TEOS intensificó la densificación. Así, se formaron grietas que comprometieron la resistencia a la corrosión.

Siloxane - poly (methylmethacrylate)-based materials are systems formed by a silicon network, to which chains of poly (methylmethacrylate) are linked by covalent bonds or by physical interactions. Their stability and adherence allow their application on substrates like tin plate in order to increase the corrosion resistance. The aim of this work is to coat tin plate with a hybrid film obtained from a sol consisting of alkoxide precursors: 3 - (trimethoxysilylpropyl) methacrylate (TMSM) and poly (methyl methacrylate) PMMA. Effect of tetraethoxysilane (TEOS) addition was evaluated. Morphology was evaluated by SEM and contact angle. Electrochemical behavior was evaluated by open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Results showed that siloxane-PMMA film obtained with a higher addition of TEOS had higher thickness. However, intense densification caused by TEOS addition promoted crack formation, thereby compromising the corrosion resistance.

Titanium and its alloys have been widely used in implants and prostheses. However, the clinical success of these biomaterials can be compromised due to failures that can occurs by loss cohesion of tissue, fracture or allergic reactions caused by the presence of dissolved metallic ions or detached solid particles by mechanical factors. Some results presented on the literature have been showed that the surface roughness of the titanium implants affects the osseointegration rate and biomechanical fixation. The present work aims to study the current density effect on the electrochemical treatment of Ti to obtain nanostructured surfaces. The samples were mechanically sanded and electrochemical treatment on acid solution. After the electrochemical treatment the samples were characterized by atomic force microscopy, profilometry and wettability tests. Preliminary results showed that is possible to control the morphology of nanostructured surfaces by electrochemical treatment parameters control.

O emprego do titânio e outras ligas como implantes e próteses têm tido grande repercussão clínica nos últimos anos. No entanto, apesar do êxito clínico, esses biomateriais têm apresentado problemas devido a falhas que podem ocorrer pelo desgaste, fratura ou por reações alérgicas ocasionadas pela presença de íons metálicos dissolvidos ou partículas sólidas desprendidas do implante por fenômeno mecânico. Há inúmeros relatos na literatura demonstrando que a rugosidade da superfície de implantes de titânio afeta a taxa de osseointegração e fixação biomecânica. Nesse contexto, o presente trabalho tem por objetivo estudar o efeito da densidade de corrente no processo de tratamento eletroquímico do Ti visando à obtenção de superfícies nanoestruturadas. Para isso as amostras de Ti foram lixadas mecanicamente e submetidas um processo de tratamento eletroquímico em solução ácida. Nessa etapa do estudo variou-se a densidade de corrente, mantendo fixos os demais parâmetros. Após o processo de tratamento eletroquímico as amostras foram caracterizadas por microscopia de força atômica, perfilometria e ensaios de molhabilidade. Resultados preliminares mostraram que é possível controlar a morfologia de superfícies nanoestruturadas a partir do controle da densidade de corrente.

Las películas hibridas actúan como una barrera entre el substrato y el medio, reduciendo la velocidad de entrada del agua, electrolito, oxígeno y la penetración deiones agresivos hasta el metal, disminuyendo la velocidad de corrosión del substrato. Los principales factores que influyen en la resistencia a la corrosión de las películas híbridas son: el tiempo de curado, la concentración del baño, el pH de la solución de hidrólisis y el tiempo de hidrólisis. En este trabajo, se realizaron las pruebas con cuatro diferentes tiempos de hidrólisis (1, 3, 24 y 48 horas), el acero galvanizado fue revestido con una película híbrida obtenida a partir de un sol constituido por los precursores alcohoxidos 3-(trimetoxisililpropil) metacrilato (TMSPMA) y Tetraetoxisilano (TEOS) con adición de nitrato de cerio [0,01 M]. La caracterización de las películas fue realizada por MEB, perfilometria, ángulo de contacto, polarización y espectroscopia de impedancia electroquímica. Los resultados muestran que el tiempo de hidrólisis interfiere en la obtención de la película híbrida y consecuentemente en las propiedades protectoras de la película.

The hybrid films act as a barrier layer between the substrate and the environment. This kind of coating reduces the electrolyte permeability, decreasing the corrosion rate of the substrate. However, many variables influenced the corrosion resistance of hybrid coating. The main factors that influence the thickness of the films are: temperature, curing time, the concentration alcooxide precursors on the bath, the pH of the hydrolysis and the hydrolysis time. In this study, the galvanized steel was coated with and hybrid film obtained from precursors consisting of a sol alcooxide 3-(trimetoxisililpropil) methacrylate (TMSPMA) and tetraethoxysilane (TEOS) with cerium nitrate addition [0,01 M]. The hydrolysis time was varied in four levels of (1, 3, 24 and 48 hours). The characterization of the films was performed by SEM, profilometry, contact angle determination, polarization and electrochemical impedance spectroscopy measurements. Results showed that the hydrolysis time presented influence on the hybrid film properties and consequently on the protection.

Galvanized steel was coated with a hybrid film obtained from a solution formed by silane precursor 3-(trimethoxysilyl) methacrylate (TMSPMA) and tetraethoxysilane (TEOS) with addition of cerium. The use of hybrid organic-inorganic layers represents an environmentally friendly alternative to improve resistance against corrosion of a series of metallic materials. Three immersion times (2, 10 and 15 minutes) were used and the films were characterized by scanning electron microscope evaluating film wetability was at the same time. The electrochemical behavior of the coatings obtained was evaluated by open circuit potential, potentiodynamic polarization and electrochemical impedance. The results showed the effect of immersion time in the solution on the film uniformity and consequently on the corrosion resistance of these films.

Acero galvanizado fue revestido con una película híbrida a partir de una solución formada por los precursores silanos 3-(trimetoxisililpropil) metacrilato (TMSPMA) y tetraetoxisilano (TEOS) con adición de cerio. El uso de capas hibridas orgánico-inorgánico representa una alternativa ambientalmente aceptable para mejorar la resistencia de una serie de materiales metálicos frente a los procesos corrosivos. Se emplearon tres tiempos de inmersión (2, 10 y 15 minutos) y se caracterizaron las películas mediante microscopia electrónica de barrido, evaluando también el carácter hidrofóbico de las películas. El comportamiento electroquímico de los revestimientos obtenidos fue determinado por el monitoreo del potencial de circuito abierto, polarización potenciodinámica e impedancia electroquímica. Los resultados que se obtuvo evidenciaron el efecto del tiempo de permanencia dentro de la solución en la uniformidad de la película y consecuentemente sobre la resistencia a la corrosión del mismo.

This work presents a study on the behavior of silane films Gamma-Aminopropyl triethoxysilane and N-(beta-aminoethyl)-gamma-Aminopropyl trimethoxysilane, obtained by dip-coating process on galvanized steel. The films were cured by thermal and ultraviolet irradiation cure processes. The substrates and zinc-based coatings are usually employed as surface treatment to improve the corrosion resistance but they employ hexavalent chromium that has a high degree of toxicity. Polymer films containing organofunctional silanes have been studied as an alternative to the passivation of zinc-based substrates. The silane coatings were evaluated by electrochemical tests and contact angle. The film morphology was characterized by scanning electron microscopy. The results showed that the films obtained presented a homogeneous coverage and that the influence of silane employed in the formulation was evident, as well as the cure parameters.

Se presenta un estudio del comportamiento de películas de silanos Gamma-Aminopropyl tirethoxysilano y del N-(Beta-Aminoethyl)-Gamma-Aminopropyl trimethoxysilano aplicados por el proceso de revestimiento por inmersión (dip-coating) sobre el acero galvanizado. Se usan los mecanismos de curado térmico y curado por irradiación ultravioleta. Los substratos y revestimientos a base de zinc reciben normalmente un tratamiento de superficie para mejorar la resistencia a la corrosión, pero usan cromo hexavalente que presenta un elevado grado de toxicidad. Las películas poliméricas conteniendo silanos organofuncionales surgen como alternativa para la pasivación de substratos a base de zinc. Los revestimientos de silano obtenidos fueron evaluados a partir de ensayos electroquímicos y ángulos de mojabilidad y la morfología fue caracterizada por microscopía electrónica de barrido. Los resultados muestran que las películas elaboradas presentan una cobertura homogénea y que el tipo de silano empleado tiene influencia en la formulación y en los parámetros de curado.