LARISSA OLIVEIRA BERBEL

LARISSA OLIVEIRA BERBEL

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Corrosion mechanism of Ti-6Al-4V morse taper dental implants connected to 316 L stainless steel prosthetic abutment
2022 - BERBEL, LARISSA O.; VIVEIROS, BARBARA V.G. de; MICELLI, ANA L.P.; NIGRO, FREDERICO; ROSSI, JESUALDO L.; COSTA, ISOLDA
The aim of this work was to investigate the effect of galvanic coupling between stainless steel AISI 316 L abutment type Morse taper and implant made of ASTM F1108–14 Ti-6Al-4V alloy. The assembly of the two alloys was carried out using mechanical imbrication by means of successive strikes at 0.05 J force onto the abutment inserted in the implant along the centerline. Corrosion attack at the interface of the alloys was evaluated according to the number of strikes used for joining the parts. Corrosion resistance was evaluated for the samples by open circuit potential measurements as function of time and scanning vibrating electrode technique (SVET) and scanning ion selective electrode technique (SIET) in phosphate buffer solution with pH adjusted to 3.0, and into which hydrogen peroxide was added to simulate tissue inflammatory conditions. Samples were evaluated at the cross and longitudinal sections. Results indicated that the number of strikes used in assembling affected corrosion susceptibility. The lowest amount of corrosion products was associated to the highest number of strikes used. The corrosion resistance was related to the characteristics of the crevice between the implant and the abutment.
Niobium- and titanium-based coating for the protection of carbon steel SAE 1020 against corrosion
2022 - HELLEIS, RODRIGO; MAIA, GUILHERME A.R.; CASTRO, ERYZA G. de; BERBEL, LARISSA O.; COSTA, ISOLDA; BANCZEK, EVERSON do P.
Purpose: The purpose of this paper is to evaluate the protection against corrosion of carbon steel SAE 1020 promoted by a niobium- and titanium-based coating produced from a resin obtained by the Pechini method. Design/methodology/approach: A resin was prepared with ammonium niobium oxalate as niobium precursor and K2TiF6 as titanium precursor. Carbon Steel SAE 1020 plates were dip coated in the resin and calcinated for 1 h at 600 ºC. Scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction were used to characterize the coating morphologically and structurally. Open circuit potential, electrochemical impedance spectroscopy, anodic potentiodynamic polarization and scanning vibrating electrode technique were used to evaluate the corrosion protection of the coating. Findings: The electrochemical analyses evidence slight protection against corrosion of the coating by itself; however, the needle-like crystal structure obtained may potentially provide a good anchorage site, suggesting the coating could be used as a pretreatment that may present similar application to phosphating processes, generating lower environmental impacts. Originality/value: Due to increasingly restrictive environmental laws, new environmentally friendlier surface treatments must be researched. This paper approaches this matter using a combination of niobium- and titanium-based coating, produced by a cleaner process, the Pechini method.
The corrosion behavior on AA2050-T84 and AA7050-T7451 welded and non-welded by FSW
2021 - VIVEIROS, BARBARA V.G. de; BERBEL, LARISSA O.; DONATUS, UYIME; COSTA, ISOLDA
In this work, the corrosion resistance of the AA2050-T84 and AA7050-T7451 alloys welded by FSW and non-welded was investigated using chloride solutions. The corrosion resistance, microstructure and microhardness were studied. Microhardness measurements at the cross section and at the top surface of the weld identified significant differences between the various zones resulting from FSW. Characterization of the corrosion resistance was carried out by electrochemical and immersion tests. Localized electrochemical techniques were used in this work, specifically scanning vibrating electrode technique (SVET) and scanning ion-selective electrode technique (SIET). The results showed that the most electrochemically active zone at of the welded alloys was the thermomechanically affected zone (TMAZ). This zone corresponds to the transition between the two alloys. In the top surface of the welded alloys, besides the TMAZ, the heat affected zone (HAZ) was also highly active corresponding to the transition between zones of the AA7050. This was due to the formation of hardening precipitates in the HAZ of the AA7050. In the cross-section, the high activity related to the TMAZ was due to the galvanic coupling between the two alloys where the AA7050 alloy acted as anodic zones, and the AA2050, as the cathodic ones. When the two alloys, AA2050 and AA7050, were exposed separately to 0.005 mol.L-1 NaCl or 3.5 (wt%) NaCl solutions, the AA2050 alloy showed higher electrochemical activity compared to the AA7050 alloy which was due to the higher content of active micrometric precipitates in the AA2050 alloy relatively to the AA7050. However, when the alloys were coupled, the AA2050 was cathodically protected by the AA7050 alloy.
Effect of pulsed and spray multipass MAG welding on the corrosion resistance of 316L stainless steel
2021 - SILVA, JEFFERSON; REIS, SUELLEN; MAIA, ELOA L.; TERADA, MAYSA; BUGARIN, ALINE; BERBEL, LARISSA; ANDRADE, RAYANNE A.; GUILHERME, LUIS H.; COSTA, ISOLDA
In this study, the corrosion resistance of the ASTM A-240 TP 316L stainless steel submitted to a multipass metal active gas (MAG) welding was investigated. The stainless steel was MAG welded in two modes of metal transfer: pulsed and spray with protective gas (98% Argon and 2% Oxygen). The microstructure and corrosion resistance of base metal (BM) and fusion-zone (FZ) were characterized by scanning electron microscopy (SEM), ferritescope test, and anodic polarization tests. All zones were passive in the test solution (NaCl 1.0 mol L-1) followed by passive film breakdown with a potential increase. The BM showed a higher tendency to film breakdown comparatively to the FZ. The FZ in the spray process presented a passive film with higher breakdown resistance than the pulsed FZ.
Corrosion of dental implants made of Ti-6Al-4V connected to 316L SS in agressive environment
2021 - BERBEL, LARISSA O.; VIVEIROS, BARBARA V.G. de; MICELLI, ANA L.; NIGRO, FREDERICO; ROSSI, JESUALDO L.; COSTA, ISOLDA
Implants made of dissimilar alloys, such as Ti-6Al-4V, connected to abutment of stainless steel (SS), are being considered for application as dental implants leading to galvanic corrosion. Body fluids are corrosive electrolytes that contain aggressive ions, such as chlorides, leading to localized attack at weak points of the passive film on materials used for implants fabrication. Another reason of apprehension concerning corrosion is the method of joining the different materials. This might lead to small gaps between the two materials and promote crevice conditions that stimulate localized corrosion. In this study, the corrosion resistance of a Morse taper dental implants made of Ti-6Al-4V alloy in contact to a prosthetic abutment of 316L, with the two parts joined by mechanical forces consisting of strikes, using different numbers of strikes (3, 5 and 7), was studied. The study was carried out by SVET technique in phosphate buffer solution (PBS) with an addition of H2O2 and pH adjust to 3 to simulate inflammatory conditions. The results showed high electrochemical activity at the interface between the two alloys. SVET maps showed that the Ti alloy acted as anode whereas the 316L SS as cathode. At the interface of the dissimilar alloys, large amounts of corrosion products accumulated showing the effect of the galvanic corrosion. This was mainly observed for the samples with 3 strikes for joining both alloys. The electrochemical activity was the lowest for the dental implant mounted with 5 strikes. SVET maps and SEM images showed a strong effect of crevice corrosion for the implants joined by lowest number of strikes among the testes.
Comparing the corrosion behaviour of AA2050 and AA7050 aluminium alloys by scanning vibrating electrode and scanning ion-selective electrode techniques
2022 - VIVEIROS, BARBARA V.G. de; DONATUS, UYIME; ALENCAR, MAICON C. de; BERBEL, LARISSA O.; COSTA, ISOLDA
The susceptibility to localised corrosion of the high strength alloys, AA2050-T84 and AA7050-T7451, used in the aerospace industry, was investigated in this study by localised electrochemical techniques, specifically, scanning vibrating electrode technique (SVET) and scanning ion-selective electrode technique (SIET), in 0.005 mol L−1 NaCl solution. The study was initially carried out using both alloys individually and then, coupling the two alloys and evaluating the effect of galvanic coupling between them. The results revealed that the AA2050-T84, being nobler than the AA7050-T7451, presented higher corrosion current density values when tested in isolation and the depth of corrosion penetration was significantly deeper in the AA2050-T84 alloy than in the AA7050-T7451. However, galvanic coupling of the two alloys resulted in cathodic protection of the AA2050-T84 alloy and a reduction in corrosion current densities on both alloys.
Avaliação da resistência à corrosão da liga Ti-6Al-4V para implantes dentários em ambientes aerados e deaerados
2021 - BERBEL, LARISSA O.
O titânio e suas ligas são amplamente utilizados na odontologia, principalmente como implantes dentários, devido à sua biocompatibilidade e elevada resistência à corrosão. A resistência à corrosão do titânio ocorre pela formação de um filme fino de óxido passivo de TiO2 em contato com o oxigênio. Esta camada é aderente e estável na superfície, e capaz de atuar como barreira protetora entre o substrato e o meio corrosivo. No entanto, a literatura associa a peri-implantite a grandes aumentos de produtos de corrosão de titânio e suas ligas ao redor de implantes em presença da inflamação em comparação com implantes em pessoas saudáveis. Assim, é importante a identificação dos fatores presentes no microambiente peri-implantar que possam reduzir a resistência à corrosão do titânio. O objetivo deste estudo foi investigar e simular condições inflamatórias in vitro a fim de determinar quais fatores afetam a resistência à corrosão de implantes dentários fabricados com a liga Ti-6Al-4V em solução tampão de fosfato (PBS) utilizada para simular o efeito dos fluidos corpóreos. Foram investigados os efeitos do peróxido de hidrogênio, presente em infecções orais, da albumina, a deaeração do meio (para simulação das condições de pO2 reduzida durante a inflamação) e de íons fluoreto, em solução de PBS com pH ajustados para 3,0, 4,5 e 7,0. Também foi investigada a resistência à corrosão de implantes com conexão do tipo cone Morse de Ti-6Al-4V conectado a um pilar protético de aço inoxidável 316L por meio da avaliação da influência do efeito da conexão mecânica por batidas (3, 5 e 7) no mecanismo de corrosão. A avaliação da resistência à corrosão da liga de titânio foi realizada por técnicas eletroquímicas e caracterização da superfície (MEV). Os resultados mostraram que as condições mais favoráveis ao ataque corrosivo da liga Ti-6Al-4V são a presença no meio de um forte oxidante (H2O2), do pH ácido (pH 3,0), seja em presença ou ausência de fluoreto, presença de proteína e deaeração do meio fisiológico. As condições mais agressivas são típicas de situações presentes em infecções peri-implantares e de condições de fresta. O estudo da conexão pilar-implante mostrou que na junção entre um implante de Ti-6Al-4V e o pilar protético de aço inoxidável 316 L, a condição de fresta entre as interfaces foi o fator predominante no mecanismo de corrosão prevalecendo sobre o efeito de acoplamento galvânico.
A study on corrosion resistance of ISO 5832-1 austenitic stainless steel used as orthopedic implant
2020 - BRAGUIN, L.N.M.; SILVA, C.A.J. da; BERBEL, L.O.; VIVEIROS, B.V.G. de; ROSSI, J.L.; COSTA, I.; SAIKI, M.
The ISO 5832-1 austenitic stainless steel used as biomaterial is largely applied in the area of orthopedics, especially in the manufacture of implants, such as temporary or permanent replacement of bone structures. The objective of this study was to evaluate the localized corrosion resistance of the ISO 5832-1 stainless steel used in orthopedic implants by electrochemical tests in two different solutions. The results of this study are of great interest to evaluate the corrosion of metallic implants that can result in the release of corrosion products into bodily fluids causing possible adverse biological reactions. The determination of the chemical elements in the composition of the ISO 5832-1 stainless steel was performed by neutron activation analysis (NAA). The samples for electrochemical tests were grinded with silicon carbide paper up to #4000 finishing, followed by mechanical polishing with diamond paste. The open circuit potential measurements and anodic polarization curves were obtained in solution of 0.90 wt. % of NaCl and of simulated body fluid (SBF). The results indicated that the ISO 5832-1 stainless steel presented a high resistance to crevice corrosion in simulated body fluid solution but high susceptibility to this form of corrosion in the chloride solution.
Study of ph effect on AZ31 magnesium alloy corrosion for using in temporary implants
2020 - SILVA, CAIO A.J. da; BRAGUIN, LILIAN N.M.; BERBEL, LARISSA O.; VIVEIROS, BARBARA V.G.; ROSSI, J.L.; SAIKI, M.; COSTA, I.
Currently, magnesium alloys are gaining great interest for medical applications due to their degrading properties in the human body ensuring a great biocompatibility. These alloys also provide profitable mechanical properties due similarities with human bone. However, a difficulty in applying these materials in the biomaterials industries is the corrosion prior to cell healing. The effect of the chemical composition of Mg alloys on their corrosion behavior is well known. In this study, samples of AZ31 magnesium alloy were cut into chips for elemental chemical analysis by neutron activation analysis (NAA). Concentrations of the elements As, La, Mg, Mn, Na, Sb and Zn were determined in the AZ31 alloy. Visualization tests of agar corrosion development in various media, of 0.90% sodium chloride solution (mass), phosphate buffer saline (PBS) and simulated body fluid (SBF) were performed. Visualizations of the effect of agar gel corrosion revealed pH variation during the corrosion process due to the released into the cathode. The highest released of hydroxyl ions occurred in NaCl solution compared to PBS and SBF solutions indicating that NaCl solution was much more aggressive to the alloy compared to the others.
Study of corrosion of AA 3003 aluminum in biodiesel, diesel, ethanol and gasoline media
2020 - SOARES, M.; BERBEL, L.O.; VIEIRA, C.; OLISZESKI, D.C.S.; FURSTENBERGER, C.B.; BANCZEK, E.P.
The contact between fuels and various metals used in vehicles make them susceptible to corrosion. Aluminum is a metal widely used in automotive components owing to its corrosion resistance as well as mechanical properties. The ABNT 14359 standard establishes a method for determining fuel corrosion; however, it is restricted to copper and fossil fuels. In this standard, corrosion is assessed qualitatively by visual comparison of patterns, which can lead to uncertain results. The methodology used in this study involves the immersion of metallic materials in fuels for a specific period of time for further analysis by scanning electron microscopy (SEM), and electrochemical analysis by electrochemical impedance spectroscopy (EIS) and anodic potentiodynamic polarization (APP). The results indicated that aluminum alloy AA 3003 is suitable for use in the production of vehicle components that will be in contact with biodiesel, diesel, ethanol, or gasoline, since no serious case of corrosion occurred.