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Efeito da tribocorrosão em ligas odontológicas; Effect of tribocorrosion in dental materials

Galo, Rodrigo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 27/05/2008 PT
Relevância na Pesquisa
398.64477%
A degradação de materiais metálicos odontológicos é um processo comum, que normalmente acontece devido à ação de solicitações mecânicas e/ou devido à degradação por parte do ambiente fisiológico em que o material está inserido (saliva humana). Adicionalmente, os materiais metálicos odontológicos estão muitas vezes sujeitos, nas zonas de contato com o elemento dentário ou nas zonas de contato metal/porcelana, a movimentos (devido essencialmente às cargas de mastigação) e a solicitações químicas (ambiente da cavidade bucal). Nestas condições, os materiais metálicos odontológicos estão inseridos num sistema de tribocorrosão, que suscita um processo de degradação complexo podendo levar à falha. No entanto, o filme passivo que naturalmente cresce na superfície metálica do material odontológico, pode ser danificado ou mesmo destruído durante a inserção da prótese, por abrasão do metal com o dente ou com outros materiais. Assim como os materiais dentários restauradores, os dentes estão sob exigências mecânica e química/eletroquímica, e possível efeito de sinergismo da ação combinada da corrosão e cargas mecânicas podem, em algumas circunstâncias, levar à degradação dos dentes e/ou de materiais restauradores. Neste trabalho é estudado o comportamento da corrosão e da tribocorrosão de materiais restauradores atualmente utilizados na prática odontológica (NiCr...

Tribocorrosion behavior of Ti-C-O-N nanostructured thin films (black) for decorative applications

Lima, P.; Araújo, M.; Mathew, M. T.; Rocha, L. A.; Pinto, A. M.; Chappé, J. M.; Ramos, M. D.; Marques, L.; Pierson, J. F.; Vaz, F.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
398.64477%
Abstract: In the past few years, tribocorrosion has become a focus of research because of its relevance in terms of the future in-service degradation mechanisms of materials. In the particular case of decorative coatings, tribocorrosion is certainly one of the most important issues, and sweat corrosion and human contact wear are two other factors that may act as material selection tools. Thus, the current study aimed to investigate the tribocorrosion behavior of a new class of thin films, the Ti-C-O-N system, which is being developed to be used as a surface decorative material due to its relatively dark appearance. The films were prepared by reactive magnetron sputtering. The influence of the structural features on the tribocorrosion behavior is discussed. Crown Copyright © 2013.

Tribocorrosion response of the Ti6Al4V alloys commonly used in femoral stems

Runa, M. J.; Mathew, M. T.; Rocha, Luís Augusto
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 85-93
ENG
Relevância na Pesquisa
384.55266%
In prosthesis, tribochemical reactions occur at the stem/bone interface. When coupled with micromotions it can lead to the loosening of the implant, osteolysis, release of metal ion and wear particles. The effect of these movements and the underlying mechanisms are quite unknown. This work investigates the tribocorrosion behavior of etched Ti6Al4V alloys under reciprocating sliding. Tests were performed in a phosphate buffer solution (PBS) containing proteins. A normal load of 1 N and anodic potentials of -0.1 and +0.5 V/SCE were applied. The destruction pathways of the top surface layers (adsorbed proteins, passive film) were studied. The results showed that the favorable/undesired effect of proteins in solution depends on the characteristics of the passive film under a mechanical stress. (C) 2013 Elsevier Ltd. All rights reserved.

Tribocorrosion behaviour of titanium in artificial saliva solutions

Vieira, A. C.; Ribeiro, A. R.; Rocha, L. A.; Celis, J. P.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2004 ENG
Relevância na Pesquisa
395.46266%
Dental implants are used to replace teeth lost due to decay, trauma or periodontal disease. In last years, the demand for such implants has increased exponentially due mostly to the ageing of the population and/or increased reliability of implant therapy. To choose a material for a particular rehabilitation treatment different characteristics must be considered such as mechanical strength, elastic properties, machinability, chemical resistance, etc. There is, however, one aspect that is always of prime importance; namely how the tissue at the implant site responds to the chemical disturbance imposed by the presence of a foreign material. In this work, commercially pure titanium (grade 2) was selected mainly due to its excellent corrosion behaviour and biocompatibility, that make this material one of the most used in dentistry. The tribocorrosion behaviour of the material in conditions simulating mastication, when in contact with artificial saliva solutions was investigated. Corundum was used as counterface material. The tests were performed, at MTM- KULeuven (Belgium), in a fretting machine specially adapted for tribocorrosion experiments. A normal load of 2 N was applied to the specimens and a displacement amplitude of 200µm at a frequency of 1 Hz. The number of cycles was varied between 5.000 and 10.000. In order to simulate different environmental conditions...

Tribocorrosion studies on commercially pure titanium for dental applications

Rocha, L. A.; Ribeiro, A. R.; Vieira, A. C.; Ariza, E.; Gomes, J. R.; Celis, J. P.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /06/2005 ENG
Relevância na Pesquisa
395.46266%
Tribocorrosion refers to a complex degradation of materials occurring due to the interaction between a tribological process and a corrosive environment. From the tribological point of view, the interaction with the material may include sliding or abrasive wear, erosion, impact, fretting or fatigue processes. The environmental solicitation may result from temperature, humidity, liquids or gases in permanent or intermittent contact with the materials. Failure in the metallic part or of the metal/ceramic interfaces existing in dental restorations, such as crowns and bridges, are still relatively frequent. Also, excessive degradation of dental materials is sometimes observed in other dental materials. Most of the failures are due to the simultaneous action of mechanical (wear, fretting and fatigue) and chemical (saliva) solicitations. As a consequence, the investigation of the tribocorrosion mechanisms in such systems becomes essential. Regarding this aspect, in last years particular focus is being given to the exploitation of electrochemical methods as a tool for the investigation of the combined corrosion-wear degradation of the materials. Also, it is known that the mechanical contact geometry is of crucial importance regarding the degradation behaviour. In this work the tribocorrosion behaviour of commercially pure titanium in contact with artificial saliva solutions was investigated. Tests were conducted in a reciprocating sliding geometry with movement amplitudes varying from 200 m (fretting) up to 6 mm (wear)...

Repassivation of commercially pure Ti in different saliva solutions under tribocorrosion conditions

Vieira, A. C.; Rocha, L. A.; Ariza, E.; Gomes, J. R.; Celis, J. P.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2005 ENG
Relevância na Pesquisa
391.05668%
The surface of dental implants can undergo wear during insertion and implantation into hard tissue, or, in some conditions, during its lifetime. As a consequence, the passive film presented at the implant surface can be damaged or even totally destroyed. However, if the wear action stops the surface might regenerate, giving origin to a new passive film. As all the process occurs in the presence of a chemical aggressive environment, human saliva, the material is under tribocorrosion conditions. It is also possible to introduce the concept of tribo-electrochemistry which may include two main research areas: the tribocorrosion, where the mechanical solicitations in corrosive environments are studied, and the electrochemistry of film free surfaces, where repassivation kinetics is studied after the removal of the protective oxide film on a passive metal. The main aim of this work was to study the repassivation evolution of commercially pure Ti in artificial saliva solutions. Grade 2 commercial pure titanium samples were subjected to a small alternative sliding in a pin-on-plate tribometer against a corundum ball. At the same time, open-circuit potential (OCP) measurements were performed, before, during and after mechanical disruption of the passive film. Also...

Tribocorrosion behaviour of zrNxOy thin films for decorative applications

Ferreira, S. C.; Ariza, E.; Rocha, L. A.; Vaz, F.; Cunha, L.; Carvalho, P.; Rebouta, L.; Alves, E.; Goudeau, Ph.; Rivière, J. P.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /06/2005 ENG
Relevância na Pesquisa
384.55266%
The main aim of this work is the investigation of the tribocorrosion behaviour of single layered zirconium oxynitride, ZrNxOy, thin films in alternative linear regime of sliding and immersed in an artificial sweat solution at room temperature. The films were produced by rf reactive magnetron sputtering, using a pure Zr target at a constant temperature of 300º C. Two different sets of samples were produced. In the first set of films the substrate bias voltage was the main variable, whereas in the second set, the flow rate of reactive gases (oxygen/nitrogen ratio) was varied. The control of the amount of oxygen allowed the film properties to be tailored from those of covalent zirconium nitride to those of the correspondent ionic oxide. During the wear test both the open circuit potential and the corrosion current were monitored. Also, Electrochemical Impedance Spectroscopy (EIS) tests were performed before and after sliding in order to evaluate, in detail, the modification of the protective character of the coating introduced by the joint action of wear and corrosion. The modifications of the coating microstructure and/or chemical composition induced by the variation of the deposition parameters was also evaluated and correlated with the corrosion mechanisms occurring in each system.

Tribocorrosion behaviour of ZrOxNy thin films for decorative applications

Ferreira, S. C.; Ariza, E.; Rocha, L. A.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2006 ENG
Relevância na Pesquisa
384.55266%
The aim of this work is the investigation of the tribocorrosion behaviour of single layered zirconium oxynitride, ZrOxNy, thin films in 11 reciprocating sliding and immersed in an artificial sweat solution at room temperature. During the wear tests samples were kept under 12 potentiostatic control and the corrosion current were monitored. Also, Electrochemical Impedance Spectroscopy (EIS) tests were performed before 13 and after sliding in order to evaluate, in detail, the modification of the protective character of the coating caused by the joint action of wear and 14 corrosion. The modifications of the coating structure and microstructure and/or chemical composition originated by the variation of the deposition 15 parameters were also evaluated and correlated with the corrosion mechanisms occurring in each system

Tribocorrosion behaviour of titanium grade 2 in alternative linear regime of sliding in artificial saliva solutions

Ribeiro, Ana; Rocha, L. A.; Ariza, E.; Celis, J. P.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2005 ENG
Relevância na Pesquisa
391.05668%
The demand for metallic materials in medical and dental devices is large; metals and alloys are widely used as biomedical materials and are indispensable in the medical field. In particular, toughness, elasticity, rigidity, and, some times, electrical conductivity are essential properties for metallic materials used in medical devices. In dentistry, titanium is used for restorations, orthodontic wires, and dental implants. Materials implanted in the human body are intermittently stressed with loads, which are repeated in a tremendous amount of cycles. During mastication, dental implants are simultaneously subjected to corrosion by the oral environment and to the sliding-wear process by bite forces. Dental wear can be attributed to mastication where the teeth are worn by attrition and abrasion. The main aim of the present study was to investigate the tribocorrosion behaviour of titanium grade 2 in reciprocating sliding conditions in contact with artificial saliva solutions. Particular attention is given to the relationship between mechanical damage and the electrochemical behaviour of the material. Sliding-corrosion experiments were performed using a reciprocating ball-on-flat contact configuration and the open circuit potential was monitored during the test. Also electrochemical impedance spectroscopy was used to obtain a more detailed description of the corrosion mechanisms and to characterise the passive layer that forms on the titanium surface. To reproduce the oral environment around the dental implant...

Influence of the structural, physical and chemical characteristics of titanium surface oxide layers on its tribocorrosion behaviour in contact with an artificial saliva solution

Ribeiro, Ana; Maribondo, Rubens; Martinelli, A. E.; Celis, J. P.; Gomes, J. R.; Rocha, L. A.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /10/2005 ENG
Relevância na Pesquisa
401.0507%
Titanium has been widely used for dental implant applications because their attractive properties such as low Young modulus, good fatigue strength, excellent corrosion resistance and biocompatibility. However it cannot meet all clinical requirements. 1-2 When inserted in the oral environment, dental implants are submitted to a complex degradation phenomena occurring due to the interaction of tribological and corrosive phenomena which can result on its failure. In fact, most of the failures are a result of the combined action of mechanical solicitations (sliding or abrasive wear, erosion, impact, fretting or fatigue processes) and chemical solicitations as a consequence of contact with saliva, cells or bacteria. Consequently, dental implants become part of a tribocorrosion system, and the investigation of the tribocorrosion mechanisms in such systems becomes essential. 3 Recent work has shown that wear resistance of titanium might be improved selectively using the appropriate surface treatment, such as plasma oxidation, which is also often used to enhance the osseointegration process. 4-5 The main aim of this paper is to study the influence of the characteristics of the oxide layers obtained by plasma oxidation on the tribocorrosion behaviour of c.p. Ti intended for the fabrication of dental implants.The plasma oxidation treatment were performed at three different temperatures (300...

Wear, corrosion and tribocorrosion behavior of al-based composites reinforced with al-rich intermetallic compounds

Ferreira, S. C.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Dissertação de Mestrado
Publicado em 15/12/2006 ENG
Relevância na Pesquisa
298.64475%
Dissertação de Mestrado em Processamento e Caracterização de Metais; The objective of this research work was to study the degradation (corrosion and tribocorrosion) resulting from mechanical (wear) and electrochemistry (corrosion) interactions in Al/Al3Ti and Al/Al3Zr functionally graded materials (FGMs). The influence of the spatial distribution of the platelets on the corrosion and tribocorrosion behaviour was evaluated. The Al/Al3Ti and Al/Al3Zr FGMs were produced by centrifugal casting, originating samples in the form of rings that presented radial gradients of the reinforcements. The corrosion resistance of Al/Al3Ti and Al/Al3Zr FGMs was studied using electrochemical techniques namely, open circuit potential (OCP), potenciodynamic polarization and electrochemical impedance spectroscopy (EIS). Additionally, the tribocorrosion behaviour was evaluated in a pin-on-plate configuration, under reciprocating sliding. During the tribocorrosion tests, the samples were immersed in a 0.6 M NaCl solution, and the corrosion current was measured while the samples were under potentiostatic control. Through the integration of the current density curve vs. time, the electric charge was determined, allowing the electrochemical contribution to the overall degradation process to be distinguished from that arising from the mechanical wear. The synergic action mechanisms of the system were further explained based on scanning electron microscopy (SEM) analysis. The experimental results showed that the tribocorrosion degradation of these materials is governed essentially by mechanical processes. Finally...

TiCxOy thin films for decorative applications : tribocorrosion mechanisms and synergism

Mathew, M. T.; Ariza, E.; Rocha, L. A.; Fernandes, Ana C.; Vaz, F.
Fonte: Elsevier Publicador: Elsevier
Tipo: Pré-impressão
Publicado em 18/04/2008 ENG
Relevância na Pesquisa
401.0507%
Prova Tipográfica (In Press); Recently, tribocorrosion is widely accepted as an interdisciplinary area of research and such studies on various materials are gaining more attention by scientists and engineers due to its practical and economical significances in a wide range of applications. The main objective of the present work were to investigate the tribocorrosion behaviour of single layered titanium oxycarbide, TiCxOy, thin filmso on a reciprocating sliding tribometer, and in the presence of artificial sweat solution at room temperature, by considering the practical usage of such films as a decorative coating on various components. The films were produced by DC reactive magnetron sputtering, using C pellets incrusted in the Ti target erosion area. A gas atmosphere composed of Ar and O2 was used. The Ar flow was kept constant, and the oxygen gas flow varied from 0 to 10 sccm. During the wear tests both the open circuit potential and the corrosion current were monitored. Also, electrochemical impedance spectroscopy (EIS) tests were performed before and after sliding process. The modifications on the ‘‘native’’ coating microstructure and/or chemical composition induced by the variation of the deposition parameters were also evaluated and correlated with the wear–corrosion mechanisms occurring in each system. The corrosion studies...

Influence of pH and corrosion inhibitors on the tribocorrosion behaviour of titanium in different tribological geometries

Ribeiro, Ana Rosa Lopes Pereira
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Dissertação de Mestrado
Publicado em 11/04/2007 POR
Relevância na Pesquisa
301.0507%
Dissertação de Mestrado em Processamento e Caracterização de Materiais; Nos últimos anos, o titânio tem sido utilizado em aplicações dentárias, devido às suas óptimas propriedades mecânicas, resistência à corrosão e biocompatibilidade. Contudo a falha do componente metálico do implante e o desgaste dos materiais dentários continuam a ser um motivo de preocupação. Quando o implante dentário é colocado na cavidade oral, este é sujeito a solicitações mecânicas como resultado de micro-movimentos cíclicos na interface osso/implante ou implante/abutment ou mesmo abutment/porcelana e também solicitações químicas como consequência do contacto do implante com a saliva ou substâncias orgânicas. Podemos afirmar então que o implante está inserido num sistema de tribo-corrosão, consistindo este numa degradação do material devido a interacções mecânicas e corrosivas. Como consequência a investigação dos mecanismos de tribo-corrosão nestes sistemas tornaram-se essenciais. Neste trabalho, o estudo do comportamento tribo-corrosivo de titânio em contacto com saliva artificial foi investigado. Os testes foram realizados numa geometria de deslizamento linear alternativo, com diferentes amplitude de movimento (200 μm e 6 mm) e diferentes cargas aplicadas (2 e 10 N). Para simular a cavidade oral...

TiCxOy thin films for decorative applications : tribocorrosion mechanisms and synergism

Mathew, M. T.; Ariza, E.; Rocha, L. A.; Fernandes, Ana C.; Vaz, F.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /07/2008 ENG
Relevância na Pesquisa
398.64477%
Recently, tribocorrosion is widely accepted as an interdisciplinary area of research and such studies on the various materials is gaining more attention by the scientist and engineers due to its practical and economical significances. Hence the main objective of present work was to investigate the tribocorrosion behavior of single layered titanium oxycarbide, TiCxOy, thin films on a reciprocating sliding tribo-meter, and in the presence of artificial sweat solution at room temperature. Such films can be used as a decorative coating on various components. The films were produced by dc reactive magnetron sputtering, using C pellets incrusted in the Ti target erosion area. A gas atmosphere composed of Ar and O2 was used. The Ar flow was kept constant, and the oxygen gas flow varied from 0 to 10 sccm. During the wear tests both the open circuit potential and the corrosion current were monitored. Also, Electrochemical Impedance Spectroscopy (EIS) tests were performed before and after sliding in order to evaluate, in detail, the modification of the protective character of the coating introduced by the joint action of wear and corrosion. The modifications of the coating microstructure and/or chemical composition induced by the variation of the deposition parameters were also evaluated and correlated with the wear-corrosion mechanisms occurring in each system. The effect of hardness...

Mechanical and electrochemical deterioration mechanisms in the tribocorrosion of Al alloys in NaCl and in NaNO3 solutions

Vieira, A. C.; Rocha, L. A.; Papageorgiou, Nikolaos; Mischler, S.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Artigo de Revista Científica
Publicado em //2012 POR
Relevância na Pesquisa
391.05668%
Tribocorrosion of Al-Si-Cu-Mg alloys was investigated in 0.05 M NaCl and 0.1 M NaNO3 solutions under severe sliding and controlled electrochemical conditions. A simple galvanic coupling model was developed to analyze and quantitatively predict the evolution potential of the open circuit potential during tribocorrosion. According to this model and the obtained results, galvanic coupling was established in the NaNO3 solution within the wear track between passive and mechanically depassivated areas. In the NaCl solution, galvanic coupling was established between the whole depassivated wear track and the surrounding area. This difference was attributed to different mechanical properties of the passive surfaces.

Tribocorrosion behavior of Ti–C–O–N nanostructured thin films (black) for decorative applications

Lima, P.; Araújo, M.; Mathew, M. T.; Rocha, L. A.; Pinto, A. M. P.; Chappé, J. M.; Ramos, Marta M. D.; Marques, L.; Pierson, J. F.; Vaz, F.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2013 ENG
Relevância na Pesquisa
398.64477%
In the past few years, tribocorrosion has become a focus of research because of its relevance in terms of the future in-service degradation mechanisms of materials. In the particular case of decorative coatings, tribocorrosion is certainly one of the most important issues, and sweat corrosion and human contact wear are two other factors that may act as material selection tools. Thus, the current study aimed to investigate the tribocorrosion behavior of a new class of thin films, the Ti–C–O–N system, which is being developed to be used as a surface decorative material due to its relatively dark appearance. The films were prepared by reactive magnetron sputtering. The influence of the structural features on the tribocorrosion behavior is discussed.

Tribocorrosion behaviour of hot pressed CoCrMo−Al2O3 composites for biomedical applications

Doni, Z.; Alves, A. C.; Toptan, Fatih; Pinto, A. M. P.; Rocha, L. A.; Buciumeanu, Mihaela; Palaghian, L.; Silva, F. S.
Fonte: W. S. Maney & Son Publicador: W. S. Maney & Son
Tipo: Artigo de Revista Científica
Publicado em //2014 ENG
Relevância na Pesquisa
395.46266%
Alumina/alumina wear couple can lower the wear rates and thus metallic ion releasing on load bearing metallic implant materials. However, the low fracture toughness of ceramics is still a major concern. Therefore, the present study aims to process and to triboelectrochemically characterise the 5 and 10 vol.-%Al2O3 reinforced CoCrMo matrix composites. Corrosion and tribocorrosion behaviour of the composites were investigated in 8 g L21 NaCl solution at body temperature. Corroded and worn surfaces were investigated by a field emission gun scanning electron microscope equipped with energy dispersive X-ray spectroscopy. After tribocorrosion experi- ments, wear rates were calculated using a profilometer. Results suggest that Al2O3 particle addition decreased the tendency of CoCrMo alloy to corrosion under both static and tribocorrosion conditions. However, no significant influence on the corrosion and wear rates was observed in composites mainly due to increased porosity and insufficient matrix/ reinforcement bonding.

First insight on the impact of an osteoblastic layer on the bio-tribocorrosion performance of Ti6Al4V hip implants

Runa, M. J.; Mathew, M. T.; Fernandes, Maria Helena; Rocha, Luís Augusto Sousa Marques da
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 341-351
ENG
Relevância na Pesquisa
395.46266%
In uncemented Ti6Al4V hip implants, the bone-stem interface is subjected to cyclic loading motion driven by the daily activities of the patients, which may lead to the complete failure of the implant in the long term. It may also compromise the proliferation and differentiation processes of osteoblastic cells (bone-forming cells). The main objective of this work is to approach for the first time the role of these organic materials on the bio-tribocorrosion mechanisms of cultured Ti6Al4V alloys. The colonized materials with MG63 osteoblastic-like cells were characterized through cell viability/proliferation and enzymatic activity. Tribocorrosion tests were performed under a reciprocating sliding configuration and low contact pressure. Electrochemical techniques were used to measure the corrosion kinetics of the system, under free potential conditions. All tests were performed at a controlled atmosphere. The morphology and topography of the wear scar were evaluated. The results showed that the presence of an osteoblastic cell layer on the implant surface significantly influences the tribocorrosion behavior of Ti6Al4V alloy. It was concluded that the cellular material was able to form an extra protective layer that inhibits further wear degradation of the alloy and decreases its corrosion tendency.

Understanding growth mechanisms and tribocorrosion behaviour of porous TiO2 anodic films containing calcium, phosphorous and magnesium

Oliveira, Fernando Gabriel; Ribeiro, Ana Lúcia Roselino; Perez, Geronimo; Archanjo, Braulio Soares; Gouvea, Cristol de Paiva; Araujo, Joyce Rodrigues de; Campos, Andrea Porto Carreiro; Kuznetsov, Alexei; Almeida, Clara Muniz da Silva de; Maru, Marcia Mar
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 1-12
ENG
Relevância na Pesquisa
398.64477%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); The growth of the dental implant market increases the concern regarding the quality, efficiency, and lifetime of dental implants. Titanium and its alloys are dominant materials in this field thanks to their high biocompatibility and corrosion resistance, but they possess a very low wear resistance. Besides problems related to osteointegration and bacterial infections, tribocorrosion phenomena being the simultaneous action between corrosion and wear, are likely to occur during the lifetime of the implant. Therefore, tribocorrosion resistant surfaces are needed to guarantee the preservation of dental implants.This work focused on the incorporation of magnesium, together with calcium and phosphorous, in the structure of titanium oxide films produced by micro- arc oxidation (MAO). The characterization ofmorphology, chemical composition, and crystalline structure of the surfaces provided important insights leading to (1) a better understanding of the oxide film growth mechanisms during the MAO treatment; and (2) a better awareness on the degradation process during tribocorrosion tests. The addition of magnesium was shown to support the formation of rutile which improves the tribocorrosion properties ofthe surfaces.

Non-stationary Analysis Applied to Tribocorrosion Signals; Análise não Estacionária Aplicada a Sinais de Tribocorrosão

Marco André A. Kappel; Universidade do Estado do Rio de Janeiro; Danillo Pedro Silva; Universidade do Estado do Rio de Janeiro; José María Sánchez-Amaya; Universidad de Cádiz; Roberto P. Domingos; Universidade do Estado do Rio de Janeiro; Ivan Napole
Fonte: Revista Virtual de Química Publicador: Revista Virtual de Química
Tipo: ; Formato: binary/octet-stream
Publicado em 18/09/2015 PT
Relevância na Pesquisa
395.46266%
Significant part of electrochemical and mechanical tribocorrosion signals can be non-stationary. These signals include electrochemical potential and current, and friction force. Thus, in this case, traditional analysis techniques in the frequency domain, such as the Fourier transform technique, are not suitable for the efficient signal interpretation. Techniques such as the Short-Time Fourier Transform (STFT) are typically applied in time-frequency domain to make a detailed signal analysis. However, since the method is based on choosing a fixed length window, it is not possible to simultaneously obtain the highest resolution in both time and frequency. The current paper adopted a technique to find a dynamically variable size for the window in order to efficiently analyze non-stationary signals. This procedure was applied to tribocorrosion signals of commercially pure titanium rubbed against an alumina sphere of 4.0 mm in 0.9% m/v NaCl medium. The method directly analyzes the signal in the time domain by computing the kurtosis of small centered intervals of the signal. In practice, kurtosis can detect abrupt changes in data distribution by adapting the time-frequency resolution when it is necessary. The variable STFT results are adequate for the investigation of tribocorrosion friction force and electrochemical potential/current because they present a plot in time-frequency domain without the need of a preconditioning stage...