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.
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.
Effect of implant cleaning on titanium particle dissolution and cytocompatibility
2021 - KOTSAKIS, GEORGIOS A.; BLACK, RACHEL; KUM, JASON; BERBEL, LARISSA; SADR, ALI; KAROUSSIS, IOANNIS; SIMOPOULOU, MARA; DAUBERT, DIANE
Background Peri-implantitis treatments are mainly based on protocols for teeth but have not shown favorable outcomes for implants. The potential role of titanium dissolution products in peri-implantitis necessitate the consideration of material properties in devising treatment protocols. We assessed implant cleaning interventions on (1) bacterial removal from Ti-bound biofilms, (2) Ti surface alterations and related Ti particle dissolution, and (3) cytocompatibility. Methods Acid-etched Ti discs were inoculated with human peri-implant plaque biofilms and mechanical antimicrobial interventions were applied on the Ti-bound biofilms for 30 seconds each: (1) rotary nylon brush; (2) Ti brush; (3) water-jet on high and (4) low, and compared to sterile, untreated and Chlorhexidine-treated controls. We assessed colony forming units (CFU) counts, biofilm removal, surface changes via scanning electron microscopy (SEM) and atomic force microscopy (AFM), and Ti dissolution via light microscopy and Inductively-coupled Mass Spectrometry (ICP-MS). Biological effects of Ti particles and surfaces changes were assessed using NIH/3T3 fibroblasts and MG-63 osteoblastic cell lines, respectively. Results Sequencing revealed that the human biofilm model supported a diverse biofilm including known peri-implant pathogens. WJ and Nylon brush were most effective in reducing CFU counts (P < 0.01 versus control), whereas Chlorhexidine was least effective; biofilm imaging results were confirmatory. Ti brushes led to visible streaks on the treated surfaces, reduced corrosion resistance and increased Ti dissolution over 30 days of material aging as compared to controls, which increase was amplified in the presence of bacteria (all P-val < 0.05). Ti particles exerted cytotoxic effects against fibroblasts, whereas surfaces altered by Ti brushes exhibited reduced osteoconductivity versus controls (P < 0.05). Conclusions Present findings support that mechanical treatment strategies selected for implant biofilm removal may lead to Ti dissolution. Ti dissolution should become an important consideration in the clinical selection of peri-implantitis treatments and a necessary criterion for the regulatory approval of instruments for implant hygiene.
Modifications of titanium and zirconium alloy surfaces for use as dental implants
2020 - LEITE, DANIELA M.C.; ALENCAR, MAICON C. de; MUCSI, CRISTIANO S.; ARAUJO, JOAO V.S.; TAVARES, LUIZ A.; BERBEL, LARISSA O.; ARANHA, LUIS C.; ROSSI, JESUALDO L.
The use of dental implants of titanium and its alloys has proved to be effective, through well established and documented parameters, both in the dimensions and in the manufacturing processes and also in the surgical techniques. There are clinical situations where there is a need to reduce the diameter of the implants, below 3.75 mm in diameter. In the current state of art of the implant technology it is desirable that these also have surfaces capable of decreasing the period of osseointegration. In the present work, to improve the mechanical strength of the material, an alloy of 80% of Ti and 20% of Zr % in mass was proposed and elaborated, aiming its use as biomaterial. Physical, chemical, microstructural and mechanical characterization was carried out. The surfaces of the treated samples were observed using: scanning electron microscopy (SEM); semi quantitatively chemically analyzed using dispersive energy spectroscopy (EDS: wettability of the samples was determined and, finally, the roughness was measured using optical profilometry. For the conditions used in the present work, it was concluded, that the best surface treatment for the TiZr 80/20 alloy was acid etching with 1% vol. hydrofluoric acid for 5 minutes, as this treatment presented the most prominent results of wettability and roughness simultaneously.
Estudo do comportamento frente à corrosão da liga de magnésio AZ31 de uso em implantes temporários utilizando soluções simuladoras de fluidos corpóreos
2019 - SILVA, C.A.J.; BRAGUIN, L.N.M.; VIVEIROS, B.G.; BERBEL, L.O.; ROSSI, J.L.; COSTA, I.; SAIKI, M.
Atualmente, ligas de magnésio estão ganhando grande interesse para aplicações médicas devido a sua propriedade de degradação no corpo humano, principalmente para aplicações de interesse como stents cardiovasculares e próteses ortopédicas. Estes implantes temporários fornecem uma estabilidade mecânica necessária para o reparo e corroem completamente após o tempo de vida útil e fim do tratamento. Contudo, uma dificuldade na aplicação destes materiais na indústria de biomateriais é a corrosão antecipada e precoce à cura celular. Amostras da liga de magnésio AZ31 foram cortadas em lascas e a técnica escolhida para análise química elementar foi a Análise por Ativação com Nêutrons (NAA). Irradiações de curta e longa duração foram realizadas nas amostras juntamente com padrões sintéticos no reator IEA-R1 em um fluxo de nêutrons térmicos abaixo de 4,0x1012 n cm-2s-1. Concentrações dos elementos As, La, Mg, Mn, Na, Sb e Zn foram determinadas na liga AZ31, calculadas pelo método comparativo. Para os ensaios de corrosão, as amostras foram limpas com álcool etílico, acetona e água purificada MilliQ por agitação ultrassônica, e, em seguida foram lixadas com lixas de SiC com granulometria de #500, #800, #1200, #2000 e #4000. Testes de visualização em ágar-ágar e imersão foram realizados em solução de cloreto de sódio 0,90 % (massa), solução tampão de fosfato (PBS) e solução simuladora de fluidos corpóreos (SBF) utilizando fenolftaleína como indicador ácido-base. A observação das superfícies das amostras, antes e após exposição às soluções, foi realizada por microscopia óptica (MO) e microscopia eletrônica de varredura (MEV). A superfície também foi observada após remoção dos produtos de corrosão por desmutting e irradiação para análise quantitativa pela técnica NAA. Visualizações em gel ágarágar revelaram aumento do pH local proveniente da liberação de íons hidroxila da reação catódica e menor liberação de íons ocorreu em SBF em comparação às soluções de NaCl e PBS. As micrografias da superfície evidenciaram a formação instantânea de uma camada de produtos de corrosão após uma hora de ensaio e o desmutting revelou microcavidades caracterizadas por pites.