Electro-acoustic devices such as surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices have been in commercial use for over 60 years and can be found in applications ranging from specialised scientific and military equipment to consumer products, such as mobile telephones, TV and radio receivers, etc. Today by far the largest market for electro-acoustic devices is the telecommunication industry which annually consumes approximately three billion acoustic wave filters for frequency control alone. The development of new materials and technologies for electro-acoustic devices has gained a substantial and growing interest from both academic and industrial research communities in recent years due to the enormous growth in the telecommunication industry and other forms of wireless data communication. One of the bigger issues has been to replace the single crystalline substrates with thin film piezoelectric materials deposited by reactive sputtering. This would not only reduce the manufacturing costs but will also enable high frequency of operation and a wider choice of substrate materials. However, in order to obtain the material properties required for the intended application a detailed theoretical description of the reactive sputtering process is necessary since the texture and other functional properties of the piezoelectric material are extremely sensitive to the process parameters in addition to the structure of the underlying material. This thesis studies the reactive sputtering process and its application for the fabrication of thin film electro-acoustic devices. The aim has been to gain a further insight into the process and make use of this knowledge to improve the fabrication of electro-acoustic devices. In this work modelling of the reactive sputtering process has been improved by studying certain fundamental aspects of the process and in particular the dynamics of the processes taking place during sputtering both at the target and the substrate surfaces. Consequently, highly textured thin piezoelectric aluminium nitride films have been synthesized and thin film bulk acoustic resonators (FBAR) operating in the GHz range have been fabricated and studied.

This study applied sputtering technology to prepare composite film photocatalyst TiO2/ITO for investigating the decomposition efficiency of acetone using composite TiO2/ITO made by single- and multi-layer processes. The influences of operating parameters, including sputtering operating parameters and photocatalytic operating parameters, on the decomposition efficiency of acetone were further investigated. Operating parameters investigated for the sputtering process included oxygen to argon ratio (O2/Ar), temperature, substrate, sputtering dutation, and sputtering layers, while operating parameters investigated for the photocatalytic decomposition of acetone included light wavelength, H2O concentration, O2 concentration, initial acetone concentration, and the type of photocatalysts. In the experiments, acetone was degraded by the composite film photocatalyst TiO2/ITO in a self-designed batch photocatalytic reactor. Operating parameters included light wavelength (350~400 nm, 435~500 nm, 506~600 nm), the type of photocatalysts (single-layer film photocatalyst TiO2/ITO with the thickness of 355.3, 396.6, 437.5, 487.5, and 637.5 nm; double- and triple-layer TiO2/ITO), H2O concentration (0, 50, 100, 200, and 300 ppm). The incident light with different wavelength irradiated with three 15-W lamps of near UV light or LED lamps of blue and green lights placed on the top of the photocatalytic reactor. Acetone was injected into the reactor by using a gasket syringe and vaporized for further photocatalytic degradation on the film photocatalyst TiO2/ITO placed at the bottom of the reactor. Air samples were taken to analyze acetone concentration with a GC/FID. The composite film photocatalyst TiO2/ITO was mainly composed of anatase with a few rutile. The thicknesses of the single- and IV double-layer film photocatalyst with the thickness of 473.5 nm and 506.0 nm, respectively. Experimental results indicated that the highest decomposition efficiency of acetone was obtained by using TiO2/ITO, followed by TiO2/ground glass and TiO2/glass. The highest decomposition efficiency of acetone was observed by using TiO2/ITO at 50¢XC, 20% O2, and 100 ppm H2O. In the kinetic model, the acetone decomposition of single-layer TiO2/ITO was zero-order reaction. The acetone decomposition of double-layer TiO2/ITO in high initial acetone concentration was zero-order reaction, while that in low initial acetone concentration was first-order reaction. Thus, the decomposition of acetone exerted by TiO2 film photocatalyst can be enhanced efficiently by ITO. Under the incidence of blue light, the reaction rate of acetone decomposition were 2.353¡Ñ10-5 and 3.478¡Ñ10-5 £gmole/cm2-s for using single- and double-layer TiO2/ITO, respectively. Finally, a bimolecular Langmuir-Hinshelwood (L-H) kinetic model was applied to simulate the influences of initial acetone concentration, temperature, and relative humidity on the promotion and inhibition for the photocatalytic degradation of acetone. This study revealed that the L-H kinetic model could successfully simulate the photocatalytic reaction rate of acetone.

Submitted by Nilton Francelosi Azevedo Neto (nilton@fc.unesp.br) on 2018-11-22T13:54:33Z No. of bitstreams: 1 Azevedo Neto- Tese POSMAT-2018.pdf: 3312025 bytes, checksum: 69a53514543bbe65b47c2fd62ddb6168 (MD5) / Approved for entry into archive by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br) on 2018-11-22T16:48:03Z (GMT) No. of bitstreams: 1 azevedoneto_nf_dr_bauru.pdf: 3312025 bytes, checksum: 69a53514543bbe65b47c2fd62ddb6168 (MD5) / Made available in DSpace on 2018-11-22T16:48:03Z (GMT). No. of bitstreams: 1 azevedoneto_nf_dr_bauru.pdf: 3312025 bytes, checksum: 69a53514543bbe65b47c2fd62ddb6168 (MD5) Previous issue date: 2018-09-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A motivação para este trabalho foi buscar uma melhor compreensão sobre o processo de crescimento dos filmes de óxido de cobalto pela técnica de DC magnetron sputtering reativo. Os filmes de interesse foram depositados sobre substratos de sílica amorfa (a -SiO2 ), aluminato de lantânio (LaAlO3 ) e safira - c (Al2O3- c) usando diferentes valores de potência de deposição e fluxo de oxigênio . As condições de crescimento dos filmes foram analisadas utilizando simulação computacional do processo de sputtering reativo baseada no modelo de Depla, medidas da emissão óptica das espécies presentes no plasma e monitor amento da taxa de crescimento através de uma microbalança de quartzo. Os resultados de difração de raios X mostraram que em baixa potência é obtida a fase Co3O4 espinélio, enquanto que em alta potência os filmes apresentaram a fase CoO cúbica . A s simulações computacionais do processo de sputtering reativo indicaram que , quando as potências de deposição são baixas, o processo de crescimento dos filmes ocorre com o alvo no regime “envenenado” . Em contraste, altas potencias favorece m o regime metálico do alvo. Medidas de emissão do plasma de deposição mostraram que em baixa potência de deposição a intensidade da linha de emissão do oxigênio é alta , porém com o aumento da potência sua intensidade diminui e a d a linha do cobalto aumenta. O s filmes de Co 3 O 4 depositados sobre substratos cristalinos apresentaram resultados promissores . Medidas de difração de raios X de alta resolução , utilizando radiação síncrotron , indicaram que a deposição do Co 3 O 4 sobre Al2O3 - c resultou em crescimento epitaxial na qual a direção [ 111] do cristal de Co 3 O 4 é perpendicular à superfície do substrato de safira - c (0001). Enquanto que a deposição sobre LaAlO 3 resultou em crescimento com forte textura de orientação, com as direções [220] e [400] perpendiculares à superfície dos substratos . Os espectros Raman dessas amostras apresentaram picos de vibração bem definidos e característicos da fase Co 3 O 4 e a análise do Raman polarizado do s filmes de Co 3 O 4 sobre Al 2 O 3 - c concorda m com as regras de seleção para a orientação [111] . Para os filmes c om fase Co 3 O 4 , medidas de transmitância na região do UV - Vis - NIR mostraram alta absorção na região do visível e bandas de absorção no infravermelho próximo relacionadas a transições eletrônicas dos íons de Co 2+ e Co 3+ . Para esse crescimento observou - se também resposta intensa de fotocondutividade com exc itação em 405 nm e 532 nm em 10 K. Testes preliminares de fotocatálise indicaram que os filmes de Co 3 O 4 produzidos possuem uma pequena atividade fotocatalítica para degradação do corante Rodamina B. Neste trabalho uma correlação direta entre as condições de crescimento e as mudança s de fase do s filmes foi obtida, demonstrando a versatilidade da técnica de sputtering para crescimento de filmes de óxido de cobalto para estudos científicos e aplicações tecnológicas. / The motivation for this work was to obtain a better understanding of the growth process of cobalt oxides by the DC magnetron reactive sputtering technique. The films were dep osited on amorphous silica (a-SiO2), lanthanum aluminate (LaAlO3) and sapphire-c (c-Al2O3) substrates using different values of deposition power and oxygen flow. The conditions of growth of the films were analyzed using the optical analysis of the species present in the plasma and the monitoring of the growth rate through a quartz microbalance. The X-ray diffraction results showed that at lower powers the Co3O4 phase was obtained, while at high er power s the films presented the CoO cubic phase. The computational simulations of the reactive sputtering process indicated that, at low deposition power, the gro wth process of the films occurs with the target in the "poisoned" regime, while in high powers it favors the metallic regime of the target. Plasma emission measurements showed that at low deposition power the oxygen intensity is high while at high power it s intensity decreases and that of cobalt increases. The Co 3 O 4 films deposited on crystalline substrates showed promising results. High - resolution X-ray diffraction measurements using synchrotron radiation indicated that the deposition of Co3O4 on c-Al2O3 resulted in epitaxial growth , in which the direction [111] is perpendicular to the surface of the c - sapphire (0001) substrates. However, the deposition on LaAlO 3 resulted in growth with strong texture in the directions [220] and [400]. The Raman spectra of these samples showed well - defined vibration peaks characteristic of the Co3O4 phase . The polarized Raman analysis of Co 3 O 4 deposited on c-Al2O3 agrees with the selection rules for the [111] orientation, in agreement with the high resolution X-ray diffraction analysis . In the optical transmittance measurements , t he films with Co 3 O 4 phase displayed high absorption bands in the region of the visible and near - infrared . These bands are related to el ectronic transitions of the Co2+ and Co3+ ions. For these films , strong photoconductivity responses were observed for excitations at 405 nm and 532 nm at 10 K . Preliminary photocatalysis tests indicated that the Co3O4 films produced by sputtering have a small photocatalytic activity for Rhodamine B (RhB) dye degradation. Concluding , a direct correlation between the growth conditions and the phase changes of the films was obtained, demonstrating the versatility of the sputtering technique for the growth of cobalt oxide films for scientific studies and technological applications.

Title: Sputtering of dust grains and its consequences for space processes Author: Marek Vyšinka Department: Department of Surface and Plasma Science Supervisor: prof. RNDr. Jana Šafránková, DrSc., Department of Surface and Plasma Science Abstract: A great part of matter in a space has a form of dust grains, tiny pieces of rocks with the dimensions of hundreds nanometers to hundreds micrometers. In this environment dust grains undergo collisions with energetic particles (electron, ions, UV photons) that leads to their charging and modification. The presented thesis studies ion-dust interactions and is focussed on dust grain modification through ion implantation and its destruction via sputtering process. Two compu- ter models are presented - first for computing the ion implantation profile in the grain and second, for the shape of the sputtered grain lying on the surface of a bigger object. The resulting shape of the grain is compared with that obtained experimentally. Important results of the thesis are measured sputtering yields for spherical SiO2 grains at several surface potentials obtained by simultaneous ion and electron bombardments. Keywords: ions, dust grains, sputtering, sputtering yield, implantation profile 1

O PVD (Physical Vapor Deposition- Deposição física na fase de vapor) é um meio utilizado para a produção de recobrimentos e empregado em grande escala industrial. É um processo de deposição atômica no qual o material é vaporizado de alvo sólido por sputtering e posteriormente condensado sobre a peça a ser revestida na forma de filme. O processo ocorre em uma câmara de vácuo, na presença de plasma, e por diferença de potencial os íons, na forma pura ou combinados com átomos de hidrogênio ou carbono, são movidos para a superfície do substrato. Uma técnica relativamente nova de sputtering é o HiPIMS (High Power Impulse Magnetron Sputtering) que utiliza impulsos de energia extremamente altas com densidade de potência possibilitando filmes com melhores performances e mais densos. No presente trabalho filmes de nitreto de cromo (CrN) foram depositados por duas técnicas de magnetron sputtering, HiPIMS e DCMS (Direct Current Magnetron Sputtering), variando frequência de pulso em 400 Hz, 450 Hz e 500 Hz para o HiPIMS e a tensão de polarização em 0 V, -20 V, -40V, -60V, - 100 V e -140 V para os dois processos. Foram obtidos filmes com maior dureza, menor rugosidade para HiPIMS, no entanto DCMS apresentou maior taxa de deposição. O aumento da frequência nos filmes HiPIMS, assim como o aumento da tensão de polarização negativa possibilitaram filmes com morfologia mais densa e homogênea. Este fato também foi observado com o aumento do valor de bias nos filmes depositados por DCMS. Os valores de dureza obtidos (17 ± 2 para DCMS e 26 ± 1 para HiPIMS) são superiores aos reportados na literatura e podem estar relacionados ao efeito de \"multicamadas\" obtido pela oscilação do substrato. / PVD (Physical Vapor Deposition) is a process used for coatings deposition and it is used on a large industrial scale. It is an atomic deposition process in which the material is vaporized from solid target by sputtering and then condensed onto the part to be coated in film form. The process occurs in a vacuum chamber in the presence of plasma, and by potential difference the ions in pure form or combined with hydrogen or carbon atoms are moved to the surface of the substrate. A relatively new sputtering technique is the HiPIMS (High Power Impulse Magnetron Sputtering) which uses extremely high energy pulses with power density to enable higher performance and denser films. In the present work, chromium nitride (CrN) films were deposited by two magnetron sputtering techniques, HiPIMS and DCMS (Direct Current Magnetron Sputtering), varying the pulse frequency at 400 Hz, 450 Hz and 500 Hz for the HiPIMS and the bias at 0 V, -20 V, -40 V, -60 V, -100 V and -140 V for both processes. It was obtained films with high hardness, less roughness for HiPIMS, however DCMS presented a higher rate of deposition. The increase of the frequency in the HiPIMS films, as well as the increase of the negative polarization voltage, allowed films with denser and homogeneous morphology. This fact was also observed with the increase of the value in the films deposited by DCMS. The hardness values obtained (17 ± 2 for DCMS and 26 ± 1 for HiPIMS) were higher than those reported in the literature and may be related to the \"multilayer\" effect obtained by substrate oscillation.

No description available.

Made available in DSpace on 2016-06-02T19:19:58Z (GMT). No. of bitstreams: 1 PIRAJA_Juliana_2015.pdf: 2377451 bytes, checksum: 43680057a38cc0a2429548f99564b0d8 (MD5) Previous issue date: 2015-01-30 / Financiadora de Estudos e Projetos / The study of calcium phosphate coatings, in particular hydroxyapatite for applications on metal implants, has increased in order to improve the interaction between the tissue and the implant. In this work, calcium phosphate thin films were deposited by rf-sputtering and rf-magnetron sputtering techniques over Si and Ti substrates. For the films deposited by rf-sputtering the target was pressed at 2,5x103 kg and sintered at 600° C for 1 h. For the films deposited by rf-magnetron sputtering the target was pressed in the range of 1,5x103 kg to 3,5x103 kg and sintered in the range of RT (room temperature) to 750° C for 1 h. The chemical structure, composition and morphology of the coatings were evaluated using X-ray diffraction (XRD), infrared transmission (FTIR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), thickness measurements and bioactivity evaluation over biologic fluid in vitro (SBF) procedures on the sample were made. The purpose of this work was evaluate the influence of the deposition parameters used in the sample prepared by rf-sputtering such as self bias voltage and substrate temperature on the structural properties and physicochemical characteristics of coatings. By the analysis of X-ray diffraction in samples prepared by rf-sputtering and rf-magnetron sputtering it was noted a significant crystallization of coatings resulting from the presence of (002) and (112) peaks and 30 nm grain size. Infra-red spectra results of the samples prepared by rf-sputtering and rf-magnetron sputtering showed one vibration frequency normally observed on hydroxyapatite samples at 1030 cm-1 and 520 cm-1. The presence of this very intense and defined bands indicated that the phosphate bands are well-ordered and similar to the hydroxyapatite s structure. EDS analysis showed that the ratio between the atomic concentration Ca/P of thin films prepared by rf-sputtering decreased with the increase of rf power. On the other hand, a ratio of 1,67 was obtained for coatings prepared by rf-magnetron sputtering. It was also observed that the maximum deposition rate occurred in samples prepared by rf-sputtering at 200°C. SEM analysis revealed the presence of hydroxyapatite grains uniformly distributed in the films prepared by both techniques. These results indicate that the films have potential for biomedical applications. / O estudo de recobrimentos de hidroxiapatita para aplicação em implantes metálicos tem aumentado com intuito de melhorar a interação entre o tecido e o implante. Filmes finos de hidroxiapatita foram depositados por rf-sputtering e rf- magnetron sputtering sobre substratos de Si e Ti. Para os filmes depositados por rf-sputtering, os alvos foram prensados em uma matriz cilíndrica de aço com uma carga de 2,5x103 kg e recozidos a uma temperatura de 600° C por 1 hora. Para a técnica de rf-magnetron sputtering os alvos foram prensados com uma carga de 1,5x103 kg até 3,5x103 kg e a temperatura de recozimento foi de RT (temperatura ambiente) até 750° C por 1 hora. A estrutura química, a composição e a morfologia dos recobrimentos foram caracterizadas por difração de raios-X (DRX), espectroscopia de infravermelho por transformada de Fourier (FTIR), perfilometria, microscopia eletrônica de varredura (MEV), espectrometria de dispersão de energia (EDS) e avaliação da bioatividade sobre fluido biológico in vitro (SBF) das amostras. Essa dissertação teve como objetivo avaliar a influência dos parâmetros de deposição utilizados na preparação das amostras por rf-sputtering tais como: voltagem de autopolarização (bias) e temperatura do substrato nas propriedades estruturais e características físico-químicas dos recobrimentos. Através das análises dos dados de difração de raios-x das amostras preparadas por rf-sputtering e rf-magnetron sputtering foi observado uma cristalização significativa dos recobrimentos resultante da presença de picos em (002) e (112) e tamanho de grão da ordem de 30 nm. O estudo da estrutura através de FTIR sobre as amostras preparadas por ambas as técnicas indica a presença de bandas de absorção referentes à hidroxiapatita em 1030 cm-1 e 520 cm-1. A presença dessas bandas intensas e bem definidas indica que os filmes possuem uma estrutura ordenada e próxima da estrutura da hidroxiapatita. A relação entre as concentrações atômicas Ca/P das amostras preparadas por rf-sputtering decresceu com o aumento da voltagem de autopolarização. Entretanto, uma razão próxima de 1,67 foi obtida para os recobrimentos preparados por rf-magnetron sputtering. Ainda foi observado que a taxa máxima de deposição das amostras preparadas por rf-sputtering foi obtida na temperatura do substrato de 200° C. As análises de MEV identificaram a presença de grãos de hidroxiapatita uniformemente distribuídos nos filmes preparados por ambas as técnicas. Esses resultados indicam que os filmes possuem potencial para aplicações biomédicas.

Made available in DSpace on 2016-12-08T17:19:27Z (GMT). No. of bitstreams: 1 Elementos pre-textuais.pdf: 171651 bytes, checksum: a309ff6855712fbbba44e6c5a10fefd0 (MD5) Previous issue date: 2006-06-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this work is to evaluate the corrosion resistance of Brass C360 samples coated with INCONEL 600 films, obtained by the plasma at configuration Triodo agnetron Sputtering (TMS) technique. In order to compare had been deposited films with different parameters (time of deposition and potential to the substrate) obtaining coatings with different characteristics (thicknesses, density, porosity and stress in film). Brass samples electrochemical behavior was investigated by the consist of polarize the samples of immersed test in a solution of NaCl 3.5%, to evaluate the corrosion resistance of the samples. The results show that all INCONEL 600 the films improved its corrosion resistance to the Brass substrate being more efficient the films with more time of deposition and more potential applied in the substrate. / O objetivo deste trabalho é avaliar a resistência à corrosão de amostras de Latão C360 recobertas com filmes de INCONEL 600, via plasma na configuração Triodo Magnetron Sputtering (TMS). Para fins comparativos foram depositados filmes com diferentes parâmetros (tempo de deposição e potencial no substrato), gerando revestimentos com diferentes características (espessuras, densidade, porosidade e tensão no filme). Investigou-se o comportamento das amostras de latão e seus revestimentos em ensaios eletroquímicos, que consistem em polarizar os corpos de prova imersos numa solução de NaCl 3,5%, para avaliar a resistência à corrosão das amostras. Os resultados obtidos mostram que todos os filmes de INCONEL 600 melhoram a resistência à corrosão do Latão, sendo mais eficientes os filmes com maior tempo de deposição e maior potencial (em módulo) aplicado no substrato.

Made available in DSpace on 2014-12-17T15:14:52Z (GMT). No. of bitstreams: 1 EduardoMD_DISSERT.pdf: 1460594 bytes, checksum: 3bdc57732c952c77e8ca0b42292d1e86 (MD5) Previous issue date: 2011-01-27 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In this work we deposit via non-reactive magnetron sputtering of radio-frequency nanofilmes of nitreto of aluminum(AlN). The nanofilms aluminum nitride are semiconductors materials with high thermal conductivity, high melting point, piezoelectricity and wide band gap (6, 2 eV) with hexagonal wurtzite crystal structure, belonging to the group of new materials called III-V nitrides in which together with the gallium nitride and indium nitride have attracted much interest because they have physical and chemical properties relevant to new technological applications, mainly in microelectronic and optoelectronic devices. Three groups were deposited with thicknesses nanofilms time dependent on two substrates (glass and silicon) at a temperature of 25 ? C. The nanofilms AlN were characterized using three techniques, X-ray diffraction, Raman spectroscopy and atomic force microscopy (AFM), examined the morphology of these. Through the analysis of X-rays get the thickness of each sample with its corresponding deposition rate. The analysis of X-rays also revealed that nanofilms are not crystalline, showing the amorphous character of the samples. The results obtained by the technique, atomic force microscopy (AFM) agree with those obtained using the technique of X-rays. Characterization by Raman spectroscopy revealed the existence of active modes characteristic of AlN in the samples / Neste trabalho depositamos via magnetron sputtering de r?dio-frequ?ncia n?o reativo nanofilmes de nitreto de alum?nio (AlN). Os nanofilmes de nitreto de alum?nio s?o materiais semicondutores com alta condutividade t?rmica, elevado ponto de fus?o, piezoeletricidade e largo "bandgap"(6;2 eV) com estrutura cristalina wurtz?tica hexagonal, pertencentes ao grupo de novos materiais denominados nitretos III-V que em conjunto com o nitreto de g?lio e o nitreto de ?ndio t?m despertado muito interesse por possu?rem propriedades f?sico-qu?micas relevantes para novas aplica??es tecnol?gicas, principalmente em microeletr?nica e dispositivos optoeletr?nicos. Foram depositados tr?s grupos de nanofilmes com as espessuras depend?ntes do tempo, sobre dois tipos de substratos (vidro e sil?cio) a uma temperatura de 25?C. Os nanofilmes de AlN foram caracterizados usando tr?s t?cnicas, a difra??o de raios-X, espectroscopia Raman e microscopia de for?a at?mica (AFM), analisado-se a morfologia desses. Atrav?s da an?lise dos raios-X obtemos a espessura de cada amostra com sua respectiva taxa de deposi??o. A an?lise dos raios-X tamb?m revelou que os nanofilmes n?o s?o cristalinos, evidenciando o car?ter amorfo das amostras. Os resultados obtidos atrav?s da t?cnica, microscopia de for?a at?mica (AFM) concordam com os obtidos usando a t?cnica de raios-X. A caracteriza??o por espectroscopia Raman evidenciou a exist?ncia de modos ativos caracter?sticos do AlN nas amostras analisadas

Nióbio e suas ligas são utilizados atualmente em muitas aplicações industriais por oferecerem excelente resistência à degradação em diversos meios corrosivos. Estes meios incluem atmosferas gasosas em temperaturas elevadas, como as encontradas em plantas de gaseificação de carvão existentes em usinas termelétricas para geração de energia. As atmosferas encontradas nestes meios são misturas gasosas complexasque contêm, entre outros compostos, oxigênio e enxofre. Os sulfetos são compostos menos estáveis, possuem pontos de fusão mais baixos e apresentam, freqüentemente, maiores desvios de estequiometria em relação ao óxido correspondente. Apesar de existirem estudos relacionados à aplicação de metais refratários em atmosferas sulfetantes a temperaturas elevadas, o uso de compostos de nióbio ainda não foi devidamente avaliado como revestimento protetor, havendo poucos dados disponíveis na literatura. O objetivo deste trabalho foi avaliar o efeito proporcionado por um filme de nióbio, obtido por pulverização catódica,sobre o comportamento de sulfetação isotérmica das ligas Fe-20Cr e Fe-20Cr-1Y.Os testes de sulfetação foram realizados a 500, 600 e 700°C pelo período de 2h em atmosfera H2/2%H2S. A avaliação da resistência à sulfetação foi feita por meio do ganho de massa por unidade de área exposta. Observou-se que o comportamento de sulfetação a 500ºC das ligas FeCr e FeCrY sem e com revestimento é similar. Nesta condição, nenhuma das ligas sofreu escamação. A 700ºC a liga FeCr sofreu leve escamação na forma de um pó fino, enquanto que o produto de reação formado sobre a liga FeCrY escamou na forma de placas. O efeito do nióbio se torna pronunciado a 700ºC. A camada de produto de reação formada sobre as ligas revestidas é mais fina e plástica que na liga sem revestimento. O ganho de massa por unidade de área diminuiu sensivelmente para as ligas recobertas, que não sofreram escamação. / Niobium and niobium based alloys are currently used in many industrial applications because they offer excellent resistance to degradation in various corrosive environments. These media include gaseous atmospheres at high temperatures such as those found in existing coal gasifying plants in power plants for energy generation. These atmospheres are complex gas mixtures that contain sulfur and oxygen, among other compounds. Sulphides are thermodynamically less stable, have lower melting points and often have larger deviations from stoichiometry compared to the corresponding oxides. Although there are studies regarding the use of refractory metals in high temperature sulphidizing atmospheres, the use of niobium compounds has not been adequately evaluated and there is very little studies available in the literature about its use as a protective coating. The aim of this study was to evaluate the effect of a niobium film, deposited by magnetron sputtering on the isothermal sulphidation behavior of Fe-20Cr and Fe-20Cr-1Y alloys. The sulphidation tests were carried out at 500, 600 and 700° C for 2h in H2/2% H2S atmosphere. The sulphidation resistance was determined by mass gain per unit area. The sulphidation behavior of the coated and uncoated alloys was similar at 500ºC, and none of the alloys spalled. At 700ºC FeCr alloy scalled in the form of a fine powder, while the reaction product formed on the alloy FeCrY scalled in the form of plates. The effect of niobium became pronounced at 700°C. The reaction product layer formed on the coated alloy was thinner andmore plastic than that formed on the uncoated alloy. The mass gain per unit area of the coated alloys decreased significantly and they did not scaled.