Navegando por Autor "Muller, Iduvirges Lourdes"

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Cell response and corrosion behavior of electrodeposited diamond-like carbon films on nanostructured titanium.
(2013) Manhabosco, Taíse Matte; Martins, Leo Anderson Meira; Tamborim, Silvia Margonei Mesquita; Ilha, Mariana; Vieira, M. Q.; Guma, Fátima Costa Rodrigues; Muller, Iduvirges Lourdes
Surface characteristics such as roughness and contact angle of flat and nanostructured titanium samples and diamond-like carbon films (DLC) electrodeposited on the nanostructured samples were evaluated. Also, the mechanical properties and the corrosion resistance of the samples were evaluated in phosphate buffered saline (PBS). Biocompatibility was assessed by analyzing an in vitro cell culture. Nanostructured samples presented better cell biocompatibility. DLC deposited onto nanostructured samples remained with nanostructured morphology, presented high hardness and improved corrosion resistance compared to bare titanium. The DLC films electrodeposited from acetonitrile presented higher corrosion resistance in PBS solution when compared to DLC films deposited from N,N-dimethylformamide.
Corrosion and cell viability studies of graphite-like hydrogenated amorphous carbon films deposited on bare and nitrided titanium alloy.
(2014) Santos, Adélia Moreira Marques dos; Batista, Ronaldo Junio Campos; Martins, Leo Anderson Meira; Ilha, Mariana; Vieira, Moema Queiroz; Miquita, Douglas Rodrigues; Guma, Fátima Costa Rodrigues; Muller, Iduvirges Lourdes; Manhabosco, Taíse Matte
This work presents a study of corrosion resistance and cell viability of carbon films on bare and nitride Ti–6Al–4V. Films deposited on bare alloy significantly improve the corrosion resistance. Unexpectedly, films deposited on nitrided alloy present delamination and cracking after 16 days. We associate film failure with the presence of pores combined with a weak film/substrate interaction that allows diffusion of ions at the interface. We found that films tend to diminish the osteoblastic cell viability and the observed variations on film roughness do not improve cell viability.
Corrosion, wear and wear–corrosion behavior of graphite-like a-C:H films deposited on bare and nitrided titanium alloy.
(2013) Manhabosco, Taíse Matte; Barboza, Ana Paula Moreira; Batista, Ronaldo Junio Campos; Neves, Bernardo Ruegger Almeida; Muller, Iduvirges Lourdes
This work presents a comparative wear, corrosion and wear–corrosion (the last one in a simulated physiological solution) study of graphite-like a-C:H (GLCH) films deposited on bare and nitrided Ti6Al4V alloy. Films, deposited by r.f. PACVD, presented low porosity and promoted high corrosion resistance. The friction coefficient of the films was very lowwith appreciablewear resistance at roomconditions. However, due to the simultaneous action of both load and the corrosive environment in wear–corrosion tests a marked reduction in the coating lifetime was observed. Unexpectedly, films deposited on the nitrided alloy presented a lifetime at least ten times shorter than that of films on bare alloy. We explain such a result in terms of film/substrate interaction. The weak GLCH/nitride alloy interaction facilitates fluid penetration between the film and the substratewhich leads to a fast film delamination. Such an interpretation is supported by force curve measurements, which show that the interaction between GLCH and nitrided alloy is four times weaker than that between GLCH and bare alloy.
Deposition of thin cobalt films onto silicon by galvanostatic and potentiostatic techniques.
(2009) Manhabosco, Taíse Matte; Muller, Iduvirges Lourdes
In this study, thin cobalt films were electrodeposited directly onto n-Si (100) using two different electrodeposition techniques: galvanostatic and potentiostatic. The morphological difference between galvanostatic and potentiostatic deposits was observed by atomic force microscopy (AFM) and X-ray diffraction (XRD). Analysis of the deposits by an alternating gradient field magnetometer (AGFM) showed the influence of the electrodeposition process on the magnetic properties of the film.
Electrodeposition of diamond-like carbon (DLC) films on Ti.
(2009) Manhabosco, Taíse Matte; Muller, Iduvirges Lourdes
Diamond-like carbon films (DLC) were deposited on titanium substrates in acetonitrile and N,N-dimethyl formamide (DMF) liquids by the liquid-phase electrodeposition technique at ambient pressure and temperature. The applied voltage between the electrodes was high (1200 V) due to the use of resistive organic liquids. The surface morphology was examined by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Corrosion performance of the coatings was investigated by potentiodynamic polararization tests in phosphate buffer saline solution. Raman spectroscopy analysis of the films revealed two broad bands at approximately 1360 cm_1 and 1580 cm_1, related to D and G-band of DLC, respectively. The coated Ti was tested in a ball-on-plate type wear test machine with Al2O3 balls. The films presented a low friction coefficient (about 0.1), and the films deposited from DMF presented the best wear resistance.
Eletropolimerização pulsada para confecção de camadas transportadoras de cargas foto-geradas em dispositivos fotovoltaicos orgânicos.
(2014) Yoshioka, Nathália Akemi; Rocha, Hugo Leonardo Ramos; Cazati, Thiago; Manhabosco, Taíse Matte; Muller, Iduvirges Lourdes
Neste trabalho, filmes de polianilina (PAni) depositados por eletropolimerização potenciostática pulsada foram utilizados como camada transportadora em dispositivo orgânico fotovoltaico de heterojunção. Os filmes de PAni foram depositados sobre eletrodo de óxido de índio e estanho (ITO) utilizando-se potenciais pulsados de 1,0 V e 1,5 V em solução ácida contendo 0,1 M de monômero anilina. Os filmes apresentaram coloração esverdeada, uniforme e sem descontinuidades. A morfologia dos filmes de PAni foi analisada por imagens de microscópio de força atômica (AFM) e sua estabilidade foi verificada através de curvas de voltametria cíclica. Análise de espectroscopia de absorção ultravioleta-visível (UV-Vis) evidenciou a obtenção de filmes poliméricos no estado condutor (base esmeraldina). Os filmes de PAni depositada por eletropolimerização potenciostática pulsada sob diferentes tensões foram utilizados como camada transportadora de cargas em dispositivos fotovoltaicos de heterojunção à base de polímeros conjugados. As eficiências de conversão de energia (η) dos dispositivos com estrutura ITO/PAni/MDMO-PPV_PCBM/Al foram determinadas através da curva densidade de corrente-tensão (J-V) e comparadas com os dispositivos construídos sem a camada de PAni com estrutura ITO/MDMO-PPV_PCBM/Al, e observou-se que os dispositivos contendo filmes de PAni apresentaram eficiência cerca de 4 vezes maior.
Tribocorrosão da liga Ti6Al4V em solução Salina Tamponada com Fosfato.
(2009) Manhabosco, Taíse Matte; Muller, Iduvirges Lourdes
The tribocorrosion behavior of Ti6Al4V alloy was investigated in a Phosphate Buffered Saline (PBS) solution by a reciprocating wear, using alumina ball as the counterface material, at different normal forces and sliding velocities. Dry wear experiments were performed in order to compare with the tribocorrosion experiments at open circuit potential and under anodic polarization. Dry wear induced a superior damage on the counterface, forming larger and shallower wear tracks compared with those experiments performed in PBS solution. The anodic current was increased by wear; however the volume of oxidized metal in tribocorrosion experiments correspond to a relative low percentage of the wear track volume.
Tribocorrosion of diamond-like carbon deposited on Ti6Al4V.
(2009) Manhabosco, Taíse Matte; Muller, Iduvirges Lourdes
Tribological and corrosion properties of Ti6Al4V alloy both bare and coated by diamond-like carbon (DLC) were investigated in PBS solution. The films obtained by a PACVD technique present high hardness, good corrosion and wear resistance and lower friction coefficient compared to bare alloy. Tribocorrosion tests on bare alloy showed that when wear stops, the alloy rapidly passivates. DLC films present superior wear resistance under dry conditions. However, film life is greatly reduced during tribocorrosion tests
Tribological, electrochemical and tribo-electrochemical characterization of bare and nitrided Ti6Al4V in simulated body fluid solution.
(2011) Manhabosco, Taíse Matte; Tamborim, Silvia Margonei Mesquita; Santos, C. B. dos; Muller, Iduvirges Lourdes
Tribological, electrochemical and tribo-electrochemical behaviour of bare and nitrided Ti6Al4V alloy was studied. Scanning Electron Microscopy (SEM), X-ray diffraction and microhardness profile were used to characterize the nitrided Ti6Al4V. The anticorrosive properties of nitrided Ti6Al4V in phosphate buffer saline solution (PBS), simulating the body environment, were evaluated by Electrochemical Impedance Spectroscopy (EIS). Nitriding increased the alloy resistance to corrosion and to dry wear. Resistance to tribocorrosion in PBS at the open circuit potential (OCP) for the nitrided alloy was also significantly increased compared to the bare alloy; nevertheless at an anodic potential this influence became less important.