Navegando por Autor "Radi, Polyana Alves"
Agora exibindo 1 - 5 de 5
Resultados por página
Opções de Ordenação
Item Produção e caracterização de revestimentos à base de carbono em cerâmica e aço visando aplicações biomédicas(2021-08-06) Vieira, Lúcia; Silva, Newton Soares da; Ramirez Ramos, Marco Antonio; Radi, Polyana Alves; Martins, Gislene Valdete; Vieira, Angela Aparecida; São José dos CamposA expectativa de vida vem aumentando ao longo dos anos devido ao avanço da medicina, assim o número de idosos vem crescendo, e consequentemente vem aumentando as preocupações com as doenças relacionadas com a idade, como osteoporose, artrose, bradicardia, problemas bucais e entre outros. Dessa forma, a procura por implantes ósseos e dentários vem aumentando bem como o desenvolvimento de novos materiais para serem usados como matéria prima para novos implantes tais como: cerâmica, metais e polímeros. Porém alguns desses materiais tem um custo elevado e outros podem causar problemas a longo prazo como por exemplo, a metalose. A metalose consiste em uma degradação do material quando exposto ao fluído corpóreo e é uma das causas responsáveis por quase todas as cirurgias de substituição de prótese. Esta degradação consiste no desprendimento de íons metálicos da prótese e no acúmulo desses íons sobre os tecidos moles do corpo, levando a uma necrose do tecido ou a um crescimento tumoral. Portanto, são apresentados neste trabalho algumas considerações importantes para obtenção e caracterização de filmes e revestimentos de alótropos de carbono. Estes materiais podem ser utilizados como filme ou revestimento para a proteção de materiais implantáveis, bem como para aumentar a vida útil dos implantes. Para este estudo foram produzidos e caracterizados alótropos de carbono na forma de filmes e revestimentos de carbono. Foram produzidos filmes de DLC depositados à plasma utilizando reator “Plasma Enhanced Chemical Vapor Deposition” (PECVD) e magnetron sputtering em cerâmica MgAl2O4. Foram depositados também, revestimentos de carbono contendo fases de grafite microcristalino via laser cladding em SS316L. Foram realizadas teste biológicos, caracterização mecânica e microestrutural dos filmes obtidos. Os resultados demonstraram a formação de filme de DLC via PECVD em cerâmica com e sem prata sendo melhor probabilidade estatística do filme de DLC+Ag para aplicação biomédica. No revestimento obtido por laser cladding em amostra SS316L foi observada a formação fases de grafite microcristalino e aumento da resistência mecânica do material com o revestimento e melhor probabilidade estatística de osseointegração com a incorporação de TiO2. Com as caracterizações e teste biológico foi possível selecionar o filme e revestimento com melhor probabilidade estatística para aplicação biomédica.Item SiOx Top Layer on DLC Films for Atomic Oxygen and Ozone Corrosion Protection in Aerospace Applications(Universidade Federal de São Carlos) Ferreira, Leandro Lameirão; Radi, Polyana Alves; Silva Sobrinho, Argemiro Soares da; Vieira, Lucia; Leite, Douglas Marcel Gonçalves; Recco, Abel Andre Candido; Reis, Danieli Aparecida Pereira; Massi, MarcosEvery year, billions of dollars are invested in research and development for space applications, including new systems, new technologies, and new materials. DLC (Diamond-Like Carbon) is a promising material for use in these applications, but its use faces a technological barrier, since it is severely etched by atomic oxygen and ozone. In this study, SiOx-DLC thin films were deposited as a top layer of diamond-like carbon (DLC) films on Ti-6Al-4V substrates to increase resistance against corrosion by atomic oxygen and ozone as well as meet the requirements for use in Low Earth Orbit (LEO) satellites. The corrosion resistance of the films was evaluated using oxygen plasma, and the tribological and mechanical properties were investigated. The SiOx-DLC top layer reduced the corrosion rate two orders of magnitude and increased the critical load from 16.2 ± 1.5 N to 18.4 ± 0.4 N.Item Tribocorrosion studies on DLC films with silver nanoparticles for prosthesis applications(IOP Publishing) Radi, Polyana Alves; Vieira, Lúcia; Leite, Priscila Maria Sarmeiro Corrêa Marciano; Trava-Airoldi, Vladimir Jesus; Massi, Marcos; Reis, Danieli Aparecida PereiraMetals and their alloys are very important for orthopedic applications, and the basic requirements for a successful implant are chemical stability, mechanical behavior, and biocompatibility in body fluids and tissues. For prosthesis applications, the corrosion resistance of metals is one of the major prerequisites to avoid impairment of the material properties due to degradation. The combined action of corrosion and wear on the material is called tribocorrosion and DLC (Diamond-Like Carbon) films have been extensively studied to increase prosthesis biocompatibility and to protect from corrosion. Additionally, DLC coatings can prevent the prosthesis to release toxic elements due to plastic deformation and corrosion. This paper is about tribocorrosion studies on DLC and DLC-Ag (DLC containing silver nanoparticles) on Ti-6Al-4V substrates. These films were obtained by PECVD (Plasma Enhanced Chemical Vapor Deposition) using hexane as a precursor. The tribocorrosion behavior of uncoated and coated samples was investigated in the reciprocating mode in Ringer's lactate solution. From the polarization test results, the protective efficiency of the film was calculated. Silver nanoparticles improved the corrosion resistance of the films. The protective efficiency was 15 and 19% for DLC and DLC-Ag films, respectively.Item Tribocorrosion Susceptibility and Osseointegration Studies of Silicon–Carbon–Titanium Oxide Coatings Produced on SS316L by Laser Cladding(Springer Nature Link) Vieira, Angela Aparecida; Manfroi, Lucas Augusto; Lobo, Larissa Zamboni; Santos, Thaisa Baesso; Silva, Silvelene Alessandra da; Vasconcelos, Getúlio; Radi, Polyana Alves; Silva, Newton Soares da; Vieira, LuciaMetallic implants are frequently exposed simultaneously to cyclic micromovements and a corrosive medium at the interface between implant and bone, constituting a tribocorrosive environment. Ions from natural body fluids can increase the release of debris in the wear zone. This debris can penetrate soft or hard tissue, leading to implant failure and metallic contamination of the tissues around the prosthesis. Surface modification of implants has been studied to improve the lifespan of metallic implants in the body. In this work, a CO2 laser was used to irradiate silicon carbide with and without anatase titanium oxide (TiO2), in order to produce protective coatings for improving the tribocorrosion and osseointegration performance of stainless steel (SS316L). Tribocorrosion resistance and osseointegration tests were performed using simulated body fluid (SBF), in order to understand the behavior in this environment. Chemical composition and hardness analyses showed that the coatings were effective in improving passivation of the surface, when compared to bare SS316L. Osteoblasts were well dispersed on these surfaces, displaying improved proliferation and viability, compared to the SS316L sample. A statistically significant increase of cell viability was observed when the surface was covered with a low silicon content coating.Item Wear Rate, Tribo-Corrosion, and Plastic Deformation Values of Co-Cr-Mo Alloy in Ringer Lactate Solution(MDPI) Silva, Raimundo Nonato Alves; Neto, Rui; Vieira, Angela Aparecida; Leite, Priscila Maria Sarmeiro Corrêa Marciano; Radi, Polyana Alves; Silveira, Carolina Hahn da; Santos, Marcos Dantas dos; Viana, Filomena; Vieira, LúciaThis study investigates the tribocorrosion performance of a cast Co-Cr-Mo alloy prepared using casting and electromagnetic stirring (EMS) at specific frequencies. The tribocorrosion behaviour of the alloy was evaluated when exposed to Ringer’s lactate solution to optimize the EMS parameters and improve its properties. The research focuses on biomedical implant applications and explores how EMS affects alloy wear and corrosion resistance. As did the friction coefficient and wear volume, the wear rate of samples produced with EMS frequencies of 75 Hz and 150 Hz decreased. These improvements are attributed to the ability of EMS to refine grain size and homogenize the microstructure, thereby increasing the resistance to tribocorrosion. Techniques such as scanning electron microscopy (SEM) and profilometry were used for surface and wear analysis, while mechanical properties were evaluated through instrumented indentation tests. The findings confirm that EMS improves the alloy’s durability and tribocorrosion resistance, making it highly suitable for demanding biomedical applications such as joint replacements. This highlights the importance of advanced manufacturing techniques in optimizing biomedical alloys for simulated body conditions.