ABSTRACT Introduction: Surface treatment is an important technique to increase adhesion between implants and bones, improving its mechanical characteristics and consequently the patient’s comfort. Objectives: Ni-Cr alloys were the object of study in this work, with the purpose of analyzing and evaluating the effect of thin films deposition of titanium nitride via plasma, on its surface and comparing with cathodic cage (CC) and hollow cathode (HC) methods, for dental applications. Methods: Eighteen samples were prepared and the experiment was conducted in two steps: the pre-sputtering (1h, 350 °C, gases: Ar and H) and sputtering (4h, 450 °C, gases: Ar, Ni, and H). To characterize and compare the samples with those of reference, the Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Vickers Microhardness and wettability tests were used. Results: The results presented by SEM showed that during the surface treatment using CC, voids were formed, and using HC, the samples showed a more homogenous behavior. In microhardness tests, using a 25gf load, it was possible to observe that the HC method allowed an increase of 87% when compared to the reference and treated samples. Significance: Lastly, it can be concluded that both methods are suitable for Ni-Cr alloy surface treatment, and the HC technique, a method already used by dental professionals, presents better results due to the formation of a thicker film layer.

We investigate the structural, optical, thermal-optical, and electronic properties of TiNx thin films utilizing a variety of experimental techniques, including spectroscopic ellipsometry, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, thermal lens spectroscopy, and UV-VIS spectroscopy. Our experimental results indicate a remarkable metallic character in the TiNx thin films deposited under lower N2 flow during treatment, as well as an increase in reflectance in the infrared region and thermal diffusivity as the partial N2 flow is reduced, which is consistent with previous experimental studies. The microscopic origin of these trends is explained in terms of the atomic structure of the system, where Ti atoms contribute free carriers that interact with IR radiation and N atoms create imperfections in the lattice, causing greater scattering of phonons, respectively. The experimental results also indicate that the roughness of the films produced with a lower N2 partial flow was lower than that of the films with a higher N2 partial flow. To explain the deviation of optical properties from the ideal case, surface oxidation is also investigated. This facilitates the coating of smarting windows with TiNx thin films. structural thermaloptical, thermaloptical thermal-optical techniques ellipsometry spectroscopy microscopy UVVIS UV VIS treatment reduced studies system lattice phonons respectively case investigated

Molybdenum trioxide (MoO3) thin films are generally deposit on metallic surfaces to increase their tribological performance. In this manuscript, MoOx coatings were for the first time deposited on plasma nitrided surfaces. Vickers microhardness tests, X-ray diffractometry, and micro abrasive wear tests characterized the samples. It was investigated the effect of temperature in hardness and tribological properties of austenitic stainless steel surfaces. When the temperature of plasma nitriding increases, the coating thickness and the nitrogen diffusion on the treated surface also increases, favoring the hardness of the coatings. After MoOx deposition, the predominant MoO3 phase with monoclinic and orthorhombic unit cells was observed. MoOx coatings after plasma nitriding demonstrated the highest wear resistance.

Abstract AISI D6 tool steel and AISI 304 stainless steel are among the most widely used material in the industry. However, this application field can still be expanded through the coatings deposition. In this regard, the objective of this work was to evaluate the impact of coatings application by cathodic cage technique using Hastelloy’s cathodic cage, on corrosion resistance of these steels. Two treatment temperatures were compared. The samples were characterized by Optical Microscopy, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X-Ray Diffraction with the application of the Rietveld routine and corrosion test. The results showed the formation of multiphase layers that contributed to corrosion potentials reduction for treatments at 400 °C, being more effective when applied on AISI D6. It was observed that the corrosion resistance is influenced by the temperature, which was attributed to the precipitation of chromium nitride and iron oxide at 450 ºC.

RESUMO A crescente necessidade de aumentar a produtividade do setor industrial, impulsiona o desenvolvimento de novos aços e novos tratamentos que possam melhorar o desempenho e a vida útil de ferramentas de corte, conformação e estampagem. Tratamentos de superfície assistidos por plasma destacam-se nesse contexto. Trabalhos anteriores têm demonstrado que esses revestimentos são eficientes no aumento da dureza, na resistência ao desgaste e na resistência a corrosão de diversos tipos de aços. Nesse sentido, amostras e ferramentas de aços AISI M2 e D2 termicamente tratadas foram submetidas aos processos de nitretação a plasma convencional, em gaiola catódica e tratamento duplex com o objetivo de avaliar o efeito desses tratamentos em ferramentas de conformação buscando a viabilidade da aplicação do método no setor industrial com a redução do custo de fabricação na conformação e estampagem de pregos. Ensaios de microdureza Vickers, análise por MEV e Difração de Raios-X (DRX) possibilitaram identificar propriedades mecânicas, camada de compostos e as fases presentes, respectivamente. O desempenho das ferramentas baseou-se na quantidade de pregos produzida em kg. O custo produtivo foi determinado em função da produtividade, do preço de aquisição da ferramenta e do preço da nitretação. O uso da nitretação a plasma se mostrou viável para os dois aços, destacando-se o fato de que as ferramentas de aço D2 nitretadas a 480ºC por 3 horas, obtiveram os maiores ganhos de produtividade em relação a ferramenta não nitretada. A aplicação da nitretação convencional na ferramenta de aço M2 a 480ºC por 4 horas possibilitou a redução de seu custo em 26% e redução de 3,5% sobre o custo total de produção de pregos, obtendo o melhor custo-benefício.

ABSTRACT The growing need to increase the productivity of the industrial sector, drives the development of new steels and new treatments that can improve the performance and useful life of cutting, forming and stamping tools. Plasma-assisted surface treatments stand out in this context. Previous research has shown that these coatings are efficient in increasing hardness, wear resistance and corrosion resistance of different types of steels. In this sense, samples and tools from AISI M2 and D2 heat-treated steels were subjected to conventional plasma nitriding processes, in cathodic cage and duplex treatment in order to evaluate the effect of these treatments on forming tools seeking the viability of applying the method in the industrial sector with the reduction of the manufacturing cost in the conformation and stamping of nails. Vickers microhardness tests, SEM analysis and X-Ray Diffraction (XRD) made it possible to identify mechanical properties, layer of compounds and the phases present, respectively. The performance of the tools was based on the volume of nails produced in kg. The productive cost was determined in function of productivity, the purchase price of the tool and the nitriding price. The use of plasma nitriding proved to be feasible for both steels, highlighting the fact that the D2 steel tools nitrided at 480ºC for 3 hours, obtained the greatest productivity gains in relation to non-nitrided tool. The application of conventional nitriding in the steel tool M2 at 480ºC for 4 hours made it possible to reduce its cost by 26% and reduce by 3.5% the total cost of producing nails, obtaining the best cost-benefit ratio.

Super duplex stainless steel (SDSS) combines corrosion resistance and mechanical properties, interesting to applications in the oil extraction industry. In this process, wear between the tools friction and rocky materials occurs with SDSS pipes. Due to the low tribological properties, plasma nitriding process is applied to provide a surface layer with excellent wear resistance and without significant losses in corrosion resistance. Here, conventional plasma nitriding (CPN) and cathodic cage plasma nitriding (CCPN) techniques were compared to modify SDSS surface. Before and after passing by these two nitriding processes, welded joints (WJ) were subjected to a microstructural and corrosion resistance evaluation. Aiming to characterize the final product obtained, it was used characterization techniques, such as scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results show that using the CPN technique, at 400°C, was responsible for providing greater resistance to corrosion, when analyzing the result of potentiodynamic polarization — jpassivation = 2.60x10-5 A.cm-2 and Epite = 0.83 V than the CCPN technique when applied to the SSDS, and this was attributed to the formed diffusion layer, which is composed of the expanded austenite and ferrite phases.

RESUMO A necessidade cada vez maior de transportar grandes quantidades de petróleo e gás em ambientes agressivos fez surgir uma demanda por aços de alta resistência e baixa liga (ARBL) de classificação API (American Petroleum Institute). O principal método de falha é, sem dúvida, as trincas induzidas por hidrogênio (TIH), dessa forma há uma necessidade de buscar alternativas metalúrgicas para diminuir a susceptibilidade desses materiais a esse fenômeno e algumas dessas soluções é a laminação a morno e nitretação a plasma. O presente estudo tem como objetivo avaliar a influência da laminação a morno na microestrutura e formação da camada nitretada em aço API 5L X70, para isso, amostras do aço em questão foram submetidas a laminação a morno com 49,4 % de redução com temperatura inicial de 863 °C e final de 689 °C, posteriormente, foi realizado nitretação a plasma convencional e com auxílio de gaiola catódica usando como parâmetros: 450 °C, com fluxo de gás 75 % H2 - 25 % N2 e 25 % H2 - 75 % N2, pressão 2,5 Torr. Para a caracterização, foram realizados microscopia ótica, ensaio de microdureza Vickers e difração de raios-X. Os resultados obtidos mostram que a microestrutura apresentou um menor bandeamento, em relação à microestrutura do material como recebido, através de uma maior distribuição de perlita causada pela laminação a morno. A nitretação formou uma fina camada de compostos de dureza superficial de até 670,0 HV (HV 0.05) formadas por nitretos do tipo ε (Fe3N) e γ’ (Fe4N). Estas características são importantes no combate às trincas induzidas por hidrogênio, e sugerem que a combinação dessas duas técnicas pode ser promissora.

ABSTRACT The increasing need to transport large quantities of oil and gas in aggressive environments has led to a demand for high strength and low alloy steels (HSLA) of API (American Petroleum Institute) grade. No doubt, the main failure method of these steels is hydrogen-induced cracking (HIC), so there is a need to look for metallurgical alternatives to reduce the susceptibility of these materials to this phenomenon and some of these solutions is the warm rolling and plasma nitriding. The present study aims on evaluating the influence of the warm rolling on the microstructure and formation of the nitrided layer in API 5L X70 steel. For this, samples of the steel in question were submitted to controlled warm rolling with 49.4% reduction with initial temperature 863 °C and final temperature 689 °C, posteriorly, conventional plasma nitriding and using cathodic cage in parameters were performed: 450 °C, with a gas flow of 75% H2 - 25% N2 and 25% H2 - 75% N2, pressure 2.5 Torr. For the characterization, optical microscopy, Vickers microhardness test and X-ray diffraction were performed. The obtained results show that the microstructure presented a lower banding, in relation of the material as received, through a higher distribution of perlite caused by the warm rolling. The nitriding formed a thin layer of compounds of superficial hardness of up to 670.0 HV (HV 0.05) formed by nitrides of type (Fe3N) and γ '(Fe4N). These characteristics are important in the fight against hydrogen-induced cracking, and suggest that the combination of these two techniques may be promising.

RESUMO A nitretação a plasma é realizada em ferramentas de aços rápidos para aumentar a resistência ao desgaste da aresta de corte e reduzir a tendência do material usinado em aderir na ferramenta. O objetivo do presente trabalho é estudar a viabilidade da nitretação a plasma e do tratamento duplex em brocas de aço rápidoanalisnado o desgaste de brocas de aço rápido M2 submetidas a diferentes parâmetros de nitretação a plasma e deposição de filme de nitreto de titânio (TiN). As brocas passaram primeiro pelo tratamento de nitretação com, variando-se a temperatura em 350°C, 400°C, 450°C, 500oC e 550oC, enquanto o tratamento duplex foi dividido em nitretação convencional a 500 °C seguido de deposição de um filme fino de TiN aplicado pela técnica de deposição a plasma com gaiola catódica à temperatura de 400oC e 500 °C. As brocas nitretadas a 400°C ainda foram submetidas ao processo de deposição de um filme de TiN. Todas as brocas foram caracterizadas por microdureza Vickers e foram ensaiadas em centro de usinagem CNC, onde o corpo de prova era de aço AISI 4340. Foi realizada uma análise de desempenho entre os diferentes tratamentos, onde chegou à conclusão que o tratamento que resultou melhor desempenho na usinagem foi o tratamento de nitretação a 450°C. A camada nitretada das brocas foi analisada por perfil de microdureza, Microscopia Eletrônica de Varredura, porém observou-se que o valor de microdureza aumenta com o tempo de tratamento, e que a deposição do filme de TiN teve baixa relevância no desempenho da broca.

ABSTRACT The increase in tool life corroborates to the growth of productivity in manufacturing industries. In this context, the application of surface coatings is an alternative to increase the tool life of helical drills, especially those of small diameter. This paper studies the viability of plasma nitriding and duplex treatment on high speed steel drills. The studied nitriding treatments were performed at temperatures of 450 °C and 500 °C, while the duplex treatment was divided into conventional nitriding at 500 °C followed by the deposition of a TiN thin film applied by the cathodic cage plasma deposition technique at a temperature of 500 °C. The drills were characterized by Vickers Microhardness Test, Scanning Electron Microscopy (SEM), Energy Dispersion Spectroscopy (EDS) and Performance Simulation, where the flank wear on the cutting edge and the dimensional quality of holes machined in SAE 1045 steel specimens were measured. All treatments resulted in a higher surface hardness than that of untreated material. The tools subjected to nitriding and duplex treatment at 500 ºC presented underperformance, not showing viability for application under these conditions. The nitrided drill at 450 °C showed a longer tool life than the untreated drill and produced all holes within the limits set by the 9H12 tolerance. The study showed that the application of plasma nitriding at a temperature of 450 °C contributed to increase the tool life of high speed steel drills and to improve the dimensional quality of the holes.

RESUMO Neste trabalho, filmes finos de carbono tipo diamante DLC (Diamond-like carbon) foram depositados em substratos de aço ferramenta AISI D6 por meio da técnica de deposição a plasma com gaiola catódica de grafite, com o objetivo de avaliar a influência dos parâmetros de tratamento, tais como a duração do tratamento e a polarização das amostras. As amostras tratadas foram avaliadas em termos de morfologia e estrutura por Difração de Raios X (DRX), Espectroscopia Raman e Microscopia Eletrônica de Varredura (MEV). Os resultados dos difratogramas indicaram a presença das estruturas de ferrita, grafite e diamante para as amostras tratadas com alumina e a formação de grafite com estrutura hexagonal para amostras tratadas sem alumina. Os espectros Raman identificaram a banda D e G característicos de materiais grafíticos e os melhores resultados foram obtidos para as amostras que não utilizaram alumina. As micrografias dos filmes utilizando alumina indicaram estruturas na forma de minúsculas partículas, com contornos mais claros e definidos. Já para as amostras sem alumina, os filmes DLC apresentaram um aspecto mais uniforme e de coalescência dos grãos. As camadas das amostras tratadas com alumina apresentaram as maiores espessuras de camadas, principalmente para a amostra tratada durante 6 horas. Em relação aos tratamentos sem alumina, as amostras tratadas por 5 e 6 horas apresentaram em média a maior espessura de camada. Assim, foi possível afirmar que a alumina e, também, o tempo de tratamento influenciam de forma significativa nas características de microestrutura e espessura final do filme.

ABSTRACT In this work, thin films of diamond-like carbon DLC (Diamond-like carbon) were deposited on substrates of AISI D6 tool steel by means of the plasma deposition technique with cathodic cage of graphite, with the objective of evaluating the influence of the treatment parameters, such as the duration of the treatment and the polarization of the samples. The treated samples were evaluated in terms of morphology and structure by X-ray Diffraction (XRD), Raman Spectroscopy and Scanning Electron Microscopy (SEM). The results of the diffractograms indicated the presence of the ferrite, graphite and diamond structures for the samples treated with alumina and the formation of graphite with hexagonal structure for treated samples without alumina. The Raman spectra identified the D and G bands characteristic of graphite materials and the best results were obtained for samples that did not use alumina. Micrographs of the films using alumina indicated structures in the form of tiny particles, with clearer and defined contours. As for the non-alumina samples, the DLC films presented a more uniform appearance and coalescence of the grains. The layers of the alumina treated samples had the highest layer thicknesses, especially for the treated sample for 6 hours. Regarding the treatments without alumina, the samples treated for 5 and 6 hours presented on average the highest layer thickness. Thus, it was possible to affirm that the alumina and, also, the time of treatment influence in a significant way the characteristics of microstructure and final thickness of the film.

RESUMO O Polietileno (PE) Verde é um polímero sintético que apresenta baixa energia superficial, que resulta em fraca propriedade de adesão. Esta baixa adesão, provoca alguns problemas relativos às aplicações práticas dos polímeros, como fraca aderência de tintas de impressão, revestimentos, adesivos e metais à superfície do polímero, entre outros. Uma maneira de alterar essa propriedade é por meio da aplicação de um tratamento por plasma. Neste sentido, o objetivo deste trabalho foi preparar, via extrusão plana, filmes de biocompósitos com matriz de PE Verde (PEPURO) e carga de argila Vermiculita Expandida (VMT) no teor de 1%. Os filmes foram tratados por plasma em duas condições distintas: sob atmosfera de Oxigênio (O2) (C1); e sob atmosfera correspondendo a mistura de Argônio/Hidrogênio (Ar/H2) e um posterior tratamento por plasma sob atmosfera de O2 (C2). Os resultados indicaram que os tratamentos a plasma e a incorporação de VMT aumentaram a hidrofilicidade dos filmes, sendo que a aplicação da condição 2 (C2) mostrou-se de maneira mais eficiente. O PEPURO não tratado apresentou redução significativa de resistência máxima a tração com a inserção de VMT, já com a aplicação dos tratamentos (C1 e C2) os valores de resistência foram superiores. Em relação à rugosidade foi possível verificar que a aplicação do plasma aumentou a rugosidade na superfície das amostras. Estes resultados indicaram que o aumento da hidrofilicidade e da rugosidade resultaram em um aumento significativo na interação de fluidos com a superfície e também melhora das características adesivas do polímero.

ABSTRACT Green Polyethylene (PE) is a synthetic polymer that has low surface energy, which results in poor adhesion properties. This factor causes some problems regarding the practical applications of polymers, such as poor adherence of printing inks, coatings, adhesives and metals to the surface of the polymer, among others. One way to alter this property is by applying a plasma treatment. In this sense, the objective of this work was to prepare, by flat extrusion, biocomposite films with Green PE matrix (PEPURO) and load of Expanded Vermiculite Clay (VMT) in the 1% content. The films were treated by plasma under two different conditions: under O2 atmosphere (C1); (Ar/H2) and a subsequent treatment by plasma under O2 (C2) atmosphere. The results indicated that the plasma treatments and the incorporation of VMT increased the hydrophilicity of the films, and the application of condition 2 (C2) was shown more efficiently. The untreated PEPURO presented a significant reduction of maximum tensile strength with the insertion of VMT, already with the application of treatments (C1 and C2) the resistance values were higher. In relation to the roughness it was possible to verify that the application of the plasma increased the surface roughness of the samples. These results indicated that increased hydrophilicity and roughness resulted in a significant increase in the interaction of fluids with the surface and also improvement of the adhesive characteristics of the polymer.

Polyethylene (PE) is a polymer that has a low adhesion property, which is related to its low surface energy. However, the plasma treatment aims the modification of the surface properties without affecting the polymer structure. In this sense, the objective of this work was to prepare biocomposite films via flat extrusion with Green PE matrix and Expanded Vermiculite Clay (VMT), contents of 1, 3 and 6%. The films were treated by plasma in two different ways: Oxygen (O2) atmosphere (Condition 1); and Argon/Hydrogen (Ar/H2) atmosphere followed by a plasma treatment under O2 atmosphere (Condition 2). The results of the contact angle measurements indicated that the incorporation of VMT and the conditions used for plasma treatment increased the films wettability due to the hydrophilic character of VMT and also as a consequence of the plasma. In contrast, the XRD diffractograms indicated that there were no significant changes in the films structure.

This research used the "cathodic cage (CC)" technique for TiO2 film deposition on duplex stainless steel substrate. This technique uses a multiple hollow cathode effect. Duplex stainless steel substrates were treated at temperatures of 300°C, 350°C and 400°C, giving a temperature value ratio (Ts/Tm) of 0.27 to 0.31 (Ts being the substrate temperature and Tm the melting temperature of the deposited material). Treatment times of 1, 2 and 4 hours were administered and polycrystalline TiO2 films were obtained. The films were analyzed by optical microscopy (OM), X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). During analysis, the formation of uniform films and the possibility of controlling the TiO2 phase were observed. It was also shown that with longer treatment times and higher temperatures the rutile phase predominates. For treatment times of 4 hours at all temperatures, the rutile structure was present. With treatment times of less than 4 hours, anatase was present. In addition, results showed that this simple, low cost technique can be an alternative method for depositions of TiO2 films, with the advantage of high levels of control over porosity, thickness and phase composition (anatase and rutile).

AbstractPolyester fabric samples – PET (poly (ethylene terephtalate)), were treated with oxygen plasma, in order to alter the hydrophilicity of such material. The process parameters: working pressure, current, tension and temperature were kept constant, varying only the treatment time. In order to evaluate the change caused on samples hydrophilicity, as well as the influence of the treatment time, the vertical wicking test was used. The samples were stored at standard temperature and pressure conditions, and their wettability were measured one day after the treatment and repeated after 30, 60 and 360 days, in order to check the stability of the effects produced. Scanning electron microscopy (SEM), Raman and ATR (Attenuated total reflection) spectroscopies were used to evaluate physical and chemical alterations on the samples surface. The results have shown a substantial improvement on the hydrophilicity of the treated samples compared to the non-treated sample.

Thin nitride and titanium dioxide films were produced using an innovative technique called cathodic cage depositon. Uniformity, three-dimensionality and high rate deposition are some of the advantages of this technique. In this study we discuss the influences of temperature, treatment time and gaseous atmosphere on the characteristics of the deposited films. The TiN (titanium nitride) and TiO2 (titanium dioxide) films were produced using a high deposition rate of 2,5 µm/h at a work temperature and pressure of 400°C and 150 Pa respectively. EDS technique was used to identify the chemical composition of the thin film deposited, whilst Raman spectroscopy indicated the phases present confirmed by DRX analysis. The thickness of the deposited films was studied using electron microscopy scanning. The results based on the deposition parameters confirm the great efficiency and versatility of this technique, which allows a uniform three-dimensional film deposition on any material without the appearance of stress. Compared to other techniques, cathodic cage deposition enables deposition at lower temperatures and higher pressures.

Cylindrical samples of AISI 1020 steel were nitrided, using the techniques of conventional plasma nitriding and cathodic cage. In the latter, the samples are kept at floating potential, inside of a cage that works as a cathode and to shield the samples from the cathodic potential. A systematic study was conducted in order to evaluate the efficiency of this technique in the elimination of edge effect, in comparison with conventional plasma nitriding. In addition, another comparative study of the phases obtained using the conventional plasma nitriding and nitriding with cathodic cage was performed. Two metallic cages were used, one made of austenitic stainless AISI 316 and other one made of AISI 1020 steel, to prove the effect of deposition in nitriding with cathodic cage. The samples which were nitrided by this new technique had shown nitriding rates, crystalline phases, and microhardness, similar to those samples which were nitrided conventionally. However, it was possible to confirm the elimination of edge effect through the characterization by optical microscopy and by microhardness test along the samples surfaces. The samples were characterized by optical microscopy, microhardness tests and X-ray diffraction.