Estudo da viabilidade técnica para obtenção de superfície duplex em aço inoxidável martensítico AISI 410 através do processo de deposição a plasma por gaiola catódica

The technique of plasma nitriding by the cathode cage mainly stands out for its ability to produce uniform layers, even on parts with complex geometries. In this study, it was investigated the efficiency of this technique for obtaining duplex surface, when used, simultaneously, to nitriding treatment and thin film deposition at temperatures below 500°C. For this, were used samples of AISI 41 0 Martensitic Stainless Steel and performed plasma treatment, combining nitriding and deposition of thin films of Ti and/or TiN in a plasma atmosphere containing N2-H2. It was used a cathodic cage of titanium pure grade II, cylindrical with 70 mm diameter and 34 mm height. Samples were treated at temperature 420ºC for 2 and 12 hours in different working pressures. Optical Microscopy (OM), Scanning Electron Microscopy (SEM) with micro-analysis by Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM) and analysis of Vickers Microhardness were used to investigate coating properties such as homogeneity and surface topography, chemical composition, layer thickness, crystalline phase, roughness and surface microhardness. The results showed there is a direct proportionality between the presence of H2 in plasma atmosphere and the quantity of titanium in surface chemical composition. It was also observed that the plasma treatment at lowpressure is more effective in formation of TiN thin film

Diagnóstico das espécies ativas do plasma usado em tratamentos termoquímicos do titânio

Plasma diagnostics by Optical Emission Spectroscopy were performed for electrical discharge in three gas mixture respecting the combinations z N2 y Ar x H2, z N2 y Ar x O2 e z N2 y Ar x CH4, in which the indexes z and y systematically vary from 1 to 4 and x varies from 0 to 4, every one has dimension SCCM, resulting in 80 combinations. From the all obtained spectrums, the species CH (387,1 nm), N2+ (391,4 nm), Hβ (486,1 nm), Hα (656,3 nm), Ar (750,4 nm), O (777,4 nm) e O (842,6 nm) were analyzed because of their abundance and importance on the kinetic of reaction from the plasma to surface, besides their high dependences on the gases flows. Particularly interesting z, y and x combinations were chosen in order to study the influence of active species on the surface modification during the thermochemical treatment. From the mixtures N2 Ar O2 e N2 Ar CH4 were chosen three peculiar proportions which presented luminous intensity profile with unexpected maximum or minimum values, denominated as plasma anomaly. Those plasma concentrations were utilized as atmosphere of titanium treatment maintaining constant the control parameters pressure and temperature. It has been verified a relation among luminous intensity associated to N2+ and roughness, nanohardness and O atoms diffusion into the crystalline lattice of treated titanium and it has been seen which those properties becomes more intense precisely in the higher points found in the optical profile associated to the N2+ specie. Those parameters were verified for the mixture which involved O2 gas. For the mixture which involves CH4 gas, the relation was determinate by roughness, number of nitrogen and carbon atoms diffused into the titanium structure which presented direct proportionality with the luminous intensity referent to the N2+ and CH. It has been yet studied the formation of TiCN phases on the surface which presented to be essentially directly proportional to the increasing of the CH specie and inversely proportional to the increasing of the specie N2+

Efeito do tratamento por plasma na proliferação de fibroblastos e esterilização de membranas de quitosana

Chitosan is being studied for use as dressing due their biological properties. Aiming to expand the use in biomedical applications, chitosan membranes were modified by plasma using the following gases: nitrogen (N2), methane (CH4), argon (Ar), oxygen (O2) and hydrogen (H2). The samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle, surface energy and water absorption test. Biological Tests were also performed, such as: test sterilization and proliferation of fibroblasts (3T3 line). Through SEM we observed morphological changes occurring during the plasma treatment, the formation of micro and nano-sized valleys. MFA was used to analyze different roughness parameters (Ra, Rp, Rz) and surface topography. It was found that the treated samples had an increase in surface roughness and sharp peaks. Methane plasma treatment decreased the hydrophilicity of the membranes and also the rate of water absorption, while the other treatments turned the membranes hydrophilic. The sterilization was effective in all treatment times with the following gases: Ar, N2 and H2. With respect to proliferation, all treatments showed an improvement in cell proliferation increased in a range 150% to 250% compared to untreated membrane. The highlights were the treatments with Ar 60 min, O2 60 min, CH4 15 min. Observing the results of the analyzes performed in this study, it appears that there is no single parameter that influences cell proliferation, but rather a set of ideal conditions that favor cell proliferation

Efeito antibacteriano de tecidos têxteis revestidos por prata através da técnica de deposição por plasma

In this study, it has been investigated the influence of silver film deposition onto 100% polyester woven and non-woven, on the survival of Escherichia coli and Staphylococcus aureus in contact with these surfaces. The treatment was performedin a chamber containing the working gas at low pressure (~ 10-2 mbar). Some process parameters such as as voltage: 470 V; pressure: 10-2 mbar; current : 0.40 A and gas flow: 6 and 10 cm3/min were kept constant. For the treatments with purêargon plasma using a flow of 6 and 10 cm3/min, different treatment times were evaluated, such as, 10 , 20, 30, 40, 50 and 60 minutes. Contact angle (sessile drop), measurements were used to determine the surface tension of the treated fabrics and its influence on the bacteria grow as weel as the possibilities of a biofilm formation. The formation of a silver film, as well as the amount of this element was verified byEDX technique. The topography was observed through scanning electron microscopy (SEM) to determine the size of silver grains formed on the surfaces of the fabric and assess homogeneity of treatment. The X-ray diffraction (XRD) was used to analyze the structure of silver film deposition. The woven fabric treatments enabled the formation of silver particulate films with particle size larger than the non-woven fabrics. With respect to bacterial growth, all fabrics were shown to be bactericidal for Staphylococcus aureus (S. aureus), while for the Escherichia coli (E. coli), the best results were found for the non-woven fabric (TNT) treated with a flow of 10 cm3/min to both bacteria

Superfícies de titânio modificadas termoquimicamente por plasma : avaliação da resposta biológica

This laboratory study involves the participation of a group with professionals from different areas that had contributed to the construction of a multidisciplinary knowledge, about biological response of titanium surfaces modified through thermochemical treatment by plasma. Thus, the crystalline phase was previously characterized in relation to the topography, roughness, molhability and nitrogen concentration in the samples surface. It s indispensable that materials implanted can influence in a good cellular response as well as promotes a bacteria action. Surfaces modified by plasma were exposed to different cultures such as: cellular (human osteoblastic) and bacteria (Staphylococcus epidermidis ATCC35984 and Pseudomonas aeruginosa ATCC 27853) in order to evaluate the biological response. It was evaluated the adhesion, proliferation, morphology and cellular preference of human ostheoblastic cells (HOST), as well as the formation of a biofilm and bacteria proliferation. It was still analyzed the bacteria selectivity ability in relation to the surfaces. The software Image Pro Plus was used to the counting of cells and bacteria adhered to the surface of disks. The results were submitted to the variance analysis (ANOVA), and then, by the Kruskal-Wallis test, using GraphPad Instat ® software, version 3.5 to Windows. The nitrided samples in spite of show a higher roughness and molhability showed a smaller bacteria growing and higher cellular proliferation, when compared to non treated samples, indicating that the treated material present a high efficiency to biomedical implants

Desenvolvimento de um sistema de automação para uma planta de inertização de resíduos por plasma

The traditional processes for treatment of hazardous waste are questionable for it generates other wastes that adversely affect people s health. As an attempt to minimize these problems, it was developed a system for treatment of hazardous waste by thermal plasma, a more appropriate technology since it produces high temperatures, preventing the formation of toxic pollutants to human beings. The present work brings out a solution of automation for this plant. The system has local and remote monitoring resources to ensure the operators security as well as the process itself. A special attention was given to the control of the main reactor temperature of the plant as it is the place where the main processing occurs and because it presents a complex mathematical model. To this, it was employed cascaded controls based on Fuzzy logic. A process computer, with a particular man-machine interface (MMI), provides information and controls of the plant to the operator, including by Internet. A compact PLC module is in charge of the central element of management automation and plant control which receives information from sensors, and sends it to the MMI

Desenho e Construção de um protótipo gerador de jato de plasma frio a pressão atmosférica para aplicações biomédicas

Research for better performance materials in biomedical applications are constants. Thus recent studies aimed at the development of new techniques for modification of surfaces. The low pressure plasma has been highlighted for its versatility and for being environmentally friendly, achieving good results in the modification of physic chemical properties of materials. However, it is requires an expensive vacuum system and cannot able to generate superficial changes in specific regions. Furthermore, it is limits their use in polymeric materials and sensitive terms due to high process temperatures. Therefore, new techniques capable of generating cold plasma at atmospheric pressure (APPJ) were created. In order to perform surface treatments on biomaterials in specific regions was built a prototype capable of generating a cold plasma jet. The prototype plasma generator consists of a high voltage source, a support arm, sample port and a nozzle through which the ionized argon. The device was formed to a dielectric tube and two electrodes. This work was varied some parameters such as position between electrodes, voltage and electrical frequency to verify the behavior of glow discharges. The disc of titanium was polished and there was a surface modification. The power consumed, length, intensity and surface modifications of titanium were analyzed. The energy consumed during the discharges was observed by the Lissajous figure method. To check the length of the jets was realized with Image Pro Plus software. The modifications of the titanium surfaces were observed by optical microscopy (OM ) and atomic force microscopy (AFM ). The study showed that variations of the parameters such as voltage, frequency and geometric position between the electrodes influence the formation of the plasma jet. It was concluded that the plasma jet near room temperature and atmospheric pressure was able to cause modifications in titanium surface

Influência da superfície do titânio nitretado a plasma em diferentes atmosferas na ativação de plaquetas sanguíneas

This study aimed to analyze the biological response of titanium surfaces modified by plasma Ar + N2 + H2. Titanium disks grade II received different surface treatments Ar + N2 + H2 plasma, constituting seven groups including only polished samples used as standard. Before and after treatment the samples were evaluated in terms of topography, crystal structure and wettability, using atomic force microscopy, X-ray diffraction, Raman spectroscopy and testing of the sessile drop, respectively. Rich plasma (PRP) was applied to the surfaces modified in culture plates. Images obtained by scanning electron microscopy of the adhered platelets were analyzed to verify the behavior of platelets in the different experimental conditions. We verified that the adition of H2 on plasma atmosphere resulted in more rough surfaces, with round tops. These surfaces, in contrast to that surfaces treated with high concentration of N2, are less propense to platelet aggregation and, consequently, to the formation of thrombus when applied in biomedical devices.

Estudo da viabilidade técnica para obtenção de superfície duplex em aço inoxidável martensítico AISI 410 através do processo de deposição a plasma por gaiola catódica

The technique of plasma nitriding by the cathode cage mainly stands out for its ability to produce uniform layers, even on parts with complex geometries. In this study, it was investigated the efficiency of this technique for obtaining duplex surface, when used, simultaneously, to nitriding treatment and thin film deposition at temperatures below 500°C. For this, were used samples of AISI 41 0 Martensitic Stainless Steel and performed plasma treatment, combining nitriding and deposition of thin films of Ti and/or TiN in a plasma atmosphere containing N2-H2. It was used a cathodic cage of titanium pure grade II, cylindrical with 70 mm diameter and 34 mm height. Samples were treated at temperature 420ºC for 2 and 12 hours in different working pressures. Optical Microscopy (OM), Scanning Electron Microscopy (SEM) with micro-analysis by Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM) and analysis of Vickers Microhardness were used to investigate coating properties such as homogeneity and surface topography, chemical composition, layer thickness, crystalline phase, roughness and surface microhardness. The results showed there is a direct proportionality between the presence of H2 in plasma atmosphere and the quantity of titanium in surface chemical composition. It was also observed that the plasma treatment at lowpressure is more effective in formation of TiN thin film

Diagnóstico das espécies ativas do plasma usado em tratamentos termoquímicos do titânio

Plasma diagnostics by Optical Emission Spectroscopy were performed for electrical discharge in three gas mixture respecting the combinations z N2 y Ar x H2, z N2 y Ar x O2 e z N2 y Ar x CH4, in which the indexes z and y systematically vary from 1 to 4 and x varies from 0 to 4, every one has dimension SCCM, resulting in 80 combinations. From the all obtained spectrums, the species CH (387,1 nm), N2+ (391,4 nm), Hβ (486,1 nm), Hα (656,3 nm), Ar (750,4 nm), O (777,4 nm) e O (842,6 nm) were analyzed because of their abundance and importance on the kinetic of reaction from the plasma to surface, besides their high dependences on the gases flows. Particularly interesting z, y and x combinations were chosen in order to study the influence of active species on the surface modification during the thermochemical treatment. From the mixtures N2 Ar O2 e N2 Ar CH4 were chosen three peculiar proportions which presented luminous intensity profile with unexpected maximum or minimum values, denominated as plasma anomaly. Those plasma concentrations were utilized as atmosphere of titanium treatment maintaining constant the control parameters pressure and temperature. It has been verified a relation among luminous intensity associated to N2+ and roughness, nanohardness and O atoms diffusion into the crystalline lattice of treated titanium and it has been seen which those properties becomes more intense precisely in the higher points found in the optical profile associated to the N2+ specie. Those parameters were verified for the mixture which involved O2 gas. For the mixture which involves CH4 gas, the relation was determinate by roughness, number of nitrogen and carbon atoms diffused into the titanium structure which presented direct proportionality with the luminous intensity referent to the N2+ and CH. It has been yet studied the formation of TiCN phases on the surface which presented to be essentially directly proportional to the increasing of the CH specie and inversely proportional to the increasing of the specie N2+

Efeito do tratamento por plasma na proliferação de fibroblastos e esterilização de membranas de quitosana

Chitosan is being studied for use as dressing due their biological properties. Aiming to expand the use in biomedical applications, chitosan membranes were modified by plasma using the following gases: nitrogen (N2), methane (CH4), argon (Ar), oxygen (O2) and hydrogen (H2). The samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle, surface energy and water absorption test. Biological Tests were also performed, such as: test sterilization and proliferation of fibroblasts (3T3 line). Through SEM we observed morphological changes occurring during the plasma treatment, the formation of micro and nano-sized valleys. MFA was used to analyze different roughness parameters (Ra, Rp, Rz) and surface topography. It was found that the treated samples had an increase in surface roughness and sharp peaks. Methane plasma treatment decreased the hydrophilicity of the membranes and also the rate of water absorption, while the other treatments turned the membranes hydrophilic. The sterilization was effective in all treatment times with the following gases: Ar, N2 and H2. With respect to proliferation, all treatments showed an improvement in cell proliferation increased in a range 150% to 250% compared to untreated membrane. The highlights were the treatments with Ar 60 min, O2 60 min, CH4 15 min. Observing the results of the analyzes performed in this study, it appears that there is no single parameter that influences cell proliferation, but rather a set of ideal conditions that favor cell proliferation

Efeito antibacteriano de tecidos têxteis revestidos por prata através da técnica de deposição por plasma

In this study, it has been investigated the influence of silver film deposition onto 100% polyester woven and non-woven, on the survival of Escherichia coli and Staphylococcus aureus in contact with these surfaces. The treatment was performedin a chamber containing the working gas at low pressure (~ 10-2 mbar). Some process parameters such as as voltage: 470 V; pressure: 10-2 mbar; current : 0.40 A and gas flow: 6 and 10 cm3/min were kept constant. For the treatments with purêargon plasma using a flow of 6 and 10 cm3/min, different treatment times were evaluated, such as, 10 , 20, 30, 40, 50 and 60 minutes. Contact angle (sessile drop), measurements were used to determine the surface tension of the treated fabrics and its influence on the bacteria grow as weel as the possibilities of a biofilm formation. The formation of a silver film, as well as the amount of this element was verified byEDX technique. The topography was observed through scanning electron microscopy (SEM) to determine the size of silver grains formed on the surfaces of the fabric and assess homogeneity of treatment. The X-ray diffraction (XRD) was used to analyze the structure of silver film deposition. The woven fabric treatments enabled the formation of silver particulate films with particle size larger than the non-woven fabrics. With respect to bacterial growth, all fabrics were shown to be bactericidal for Staphylococcus aureus (S. aureus), while for the Escherichia coli (E. coli), the best results were found for the non-woven fabric (TNT) treated with a flow of 10 cm3/min to both bacteria