Abstract The physical and chemical properties of multifunctional materials have been extensively studied in the last few years especially the mechanical and tribological applications and less attention has taken the electrical and optical properties. Therefore, in this work presents the growth of (Al, Ti, Si)N films deposited on common glass substrates with a maximum thickness of 1024 nm, via reactive DC magnetron sputtering, to analyze the influence of the silicon content on their crystallographic structure, optic and electric behavior. The microstructure of the films was characterized by X-ray diffraction (XRD). The films morphology was evaluated through scanning electronic microscopy (SEM). The optical measurements were carried out by means UV-vis spectroscopy, and the electrical properties were analyzed using a four-point probe. XRD analysis indicated that the films changed from a crystalline phase to an amorphous phase, and the electrical and optical response indicated that the films with higher Si content have l223.6 Ω.cm of resistivity with an energy gap of approximately 1.0 eV and an optical energy gap of 1.5 eV. This electrical property has not been previously reported in these films.

ABSTRACT: Machine components and tools subjected to aggressive environments and strong wear conditions need surfaces with good mechanical properties. The thermo-reactive deposition/diffusion (TRD) process is one of the methods used for improving the mechanical properties of these components and tools, mainly because of its low cost and good performance of the coatings deposited. Although the TRD process is widely used for coating dies, extrusion tools and punches among others, the in-service performance of cutting tools coated using the TRD process has not been extensively studied. In this study, niobium carbide coatings were deposited on cutting punches and screw taps using the TRD technique. Phase formation and micro-hardness of the coatings were studied using X-ray diffraction and Vickers measurements respectively, and the in-service performance of the coated and uncoated tools was studied through field tests conducted at different numbers of cuts. The results show that the coating significantly improves the wear resistance and the cutting performance of the tools, especially at higher numbers of cuts.

RESUMEN: Los componentes de maquinaria y las herramientas sujetas a ambientes agresivos y fuertes condiciones de desgaste necesitan superficies con buenas propiedades mecánicas. El proceso de deposición/difusión termorreactiva (TRD) es uno de los métodos usados para mejorar las propiedades mecánicas de estos componentes y herramientas, principalmente por su bajo costo y buen desempeño de los recubrimientos depositados. Aunque el proceso TRD es ampliamente usado para recubrir moldes, herramientas de extrusión y punzones entre otros, el desempeño en servicio de herramientas de corte recubiertas usando el proceso TRD no ha sido estudiado extensamente. En este estudio se depositaron recubrimientos de carburo de niobio sobre punzones de corte y machos de roscado usando la técnica TRD. La formación de fases y la microdureza de los recubrimientos se estudió usando difracción de rayos X y dureza Vickers respectivamente, y el desempeño en servicio de las herremientas recubiertas y sin recubrimiento se estudió por medio de pruebas de campo realizadas a diferente número de cortes. Los resultados muestran que el recubrimiento mejora significativamente la resistencia al desgaste y el desempeño del corte de las herramientas, especialmente a un número alto de cortes.

Bismuth titanate (BixTiyOz) has received widespread attention due to the fact that during recent times it has found important applications in strategic research fields such as optics and optoelectronic, and more recently studies have shown how their physicochemical properties may be harnessed in order to be able to use BixTiyOz, as an anticorrosive coating. In this work bismuth titanate (BixTiyOz) coatings were grown on titanium alloy (Ti6Al4V) substrates, using RF magnetron sputtering at room temperature. The main objectives of the work were quantify the evolution of crystallographic phase formation, as a function of the annealing temperature, and establish the chemical composition in order to characterize the behavior of the bismuth titanate coating as a protective coating of the corrosion. The morphology of the coating was observed via Scanning Electronic Microscopy (SEM); the crystalline structure was characterized by X-ray Diffraction (XRD) and the chemical composition was analyzed by Rutherford Backscattering Spectrometry (RBS). The corrosion resistance of the coatings was studied by Potentiodynamic polarization (PP) test (Tafel extrapolation). SEM results showed that the surface roughness of the coatings changed when the temperature of annealing increased. Similar change occurred after PP tests. The XRD analysis revealed a change in the coatings microstructure as a function of the annealing temperature, since they evolved from a completely amorphous phase to a polycrystalline phase. RBS results indicate that coatings growing at high temperature have a complex chemical composition. Finally, the electrochemical analysis showed that the corrosion resistance of the coating is much better in the amorphous phases of bismuth titanate than in the polycrystalline phases.

We present an experimental study of the structural evolution of a bilayer V X NbY C Z /Bix TiY O Z coating produced via thermo-reactive diffusion (TRD) and the RF sputtering process on D2 steel substrate. The TRD treatments were carried out in a molten mixture consisting of borax, ferro-niobium, ferro-vanadium, and aluminum, at 1313 K for 3 hours, using a resistance-heating furnace. BiX TiY O Z coatings were deposited using RF magnetron sputtering on TRD coatings, in order to carry out a study of the corrosion behavior of this compound. The crystallographic structure of the coatings was determined via X-ray diffraction (XRD), the corrosion resistance was analyzed through the po-tentiodynamic polarization test (Tafel Extrapolation) and electrochemical impedance spectroscopic analysis (EIS). XRD patterns showed that the ternary coating (VNbC2) was preferentially oriented along the [200] direction with a cubic-centered face structure, and the BiX TiY O Z coatings were amorphous. The electrochemical studies showed that the resistance corrosion of the coatings increased with respect to the bare substrate, and that polarization resistance in the bilayer coatings increased with respect to the ternary coatings, suggesting that the titanate has anticorrosive barrier effects.

In this work, niobium carbide coatings were deposited on AISIM2, H13, and D2 tool steels by thermoreactive deposition/diffusion. The carbides were obtained using salt baths composed of molten borax, aluminum, and ferroniobium at a temperature of 1020 °C for 4 hours. The coatings were observed via scanning electron microscopy. The phases were determined using X-ray diffraction, and Vickers indentation was used to determine the hardness. The electrochemical behavior was studied via potentiodynamic polarization curves to determine the rate of corrosion and electrochemical impedance spectroscopy was used to determine the resistance to polarization. The results were compared with the properties of the substrate without a coating, and in general, greater hardness and better corrosion resistance were observed with the coatings.

En este trabajo se depositaron recubrimientos de carburo de niobio sobre aceros AISI M2, H13 y D2, utilizando la técnica de deposición por difusión termorreactiva. Los carburos se obtuvieron usando baños de sales compuestos por bórax fundido, ferroniobio, ferrovanadio y aluminio a una temperatura de 1.020 °C durante 4 horas. La presencia de los recubrimientos fue observada por microscopia electrónica de barrido. Las fases fueron determinadas usando difracción de rayos X, y se utilizó microdureza para determinar la dureza. El comportamiento electroquímico fue estudiado mediante curvas de polarización potenciodinámica para determinar la densidad de corriente de corrosión, y espectroscopia de impedancia electroquímica para determinar la resistencia a la polarización. Los resultados fueron comparados con las propiedades del sustrato sin recubrimiento y en general se observó mayor dureza y mejor resistencia a la corrosión en los recubrimientos producidos.

In this work we present the results obtained from the deposition of nano-structured bismuth coatings through DC pulsed unbalanced magnetron sputtering. The coatings were grown on two substrates: silicon and AISI steel 316 L. The microstructure of the Bi coatings grown on silicon and the corrosion resistance of the Bi coatings grown on AISI steel were evaluated. The microstructure was evaluated by X-ray diffraction (XRD) and the corrosion resistance was characterized by means of polarization potentiodynamic and electrochemical impedance spectroscopy. Finally the morphology ofthe coatings was evaluated through scanning electronic microscopy (SEM). The XRD analysis indicates that the coatings are polycrystalline; the corrosion resistance tests indicate that the films with better corrosion resistance were deposited at 40 kHz. SEM micrographs show that the coatings are grown as granular form.

Trivalent electrolyte-based chromium plating represents an alternative for the major problems associated with traditional hexavalent plating. Response surface methodology was chosen in this work for designing experiments. Chromium coatings were obtained from trivalent solutions in a chloride-based bath using different operating conditions. Three concentrations (0.19, 0.38 and 0.57 mol L-1 as Cr(III) ), three pH (2.0, 3.0 and 4.0) and temperature (25°C, 32°C, 40 ºC) was varied during the experiments. Scanning electron microscopy and energy dispersive X-ray analysis were used for examining the coatings surface morphology and composition; the coulometric method was used for thickness measurement and potentiodynamic and impedance tests on 3% NaCl were made on a three-eletrode cell for studying chromium film electrochemical behavior. Large differences in morphology, thickness and corrosion resistance were observed, mainly due to variations in chromium concentration and pH solution. Crack; patterns were observed on films obtained at high pH values independently of process temperature.

Los electrolitos basados en el cromo trivalente presentan una alternativa a los problemas asociados con los recubrimientos tradicionales basados en cromo hexavalente. En este trabajo se empleó un diseño de experimentos de superficie de respuesta para observar el efecto de las variables. Los recubrimientos de cromo se obtuvieron a partir de soluciones de cloruro de cromo modificando las condiciones de electro deposición. Tres concentraciones (0.19, 0.38 y 0.57 mol L-1 de Cr(III)), tres valores de pH (2.0, 3.0 y 4.0) y tres temperaturas (25°C, 32°C y 40 ºC) se variaron durante los experimentos. La morfología y composición de los recubrimientos se analizó por medio de microscopía electrónica de barrido y la sonda de análisis de dispersión de rayos X acoplada al microscopio; el espesor de los mismos se midió por titulación coulombimétrica y el comportamiento electroquímico a la corrosión se estudió por medio de polarización potenciodinámica y espectroscopía de impedancia electroquímica en NaCl 3%. Se observaron grandes diferencias en la morfología, espesor y resistencia a la corrosión debido principalmente a la variación en la concentración de cromo y al pH de la solución. Se observaron patrones de agrietamiento cuando el depósito se obtuvo a altos valores de pH independientemente de la temperatura del electrolito.

Thin films of zirconium oxynitride were grown on common glass, silicon (100) and stainless steel 316 L substrates using the reactive rf magnetron sputtering technique. The films were analyzed through structural, morphological, and biocompatibility studies. The structural analysis was carried out using X-ray diffraction (XRD), and the morphological analysis was carried out using scanning electron microscopy (SEM) and atomic force microscopy (AFM). These studies were done as a function of growth parameters, such as power applied to the target, substrate temperature, and flow ratios. The corrosion resistance studies were made on samples of stainless steel 316 L coated and uncoated with Zr xNyO films, through of polarization curves. The studies of biocompatibility were carried out on zirconium oxynitride films deposited on stainless steel 316L through proliferation and cellular adhesion. The XRD analysis shows that films deposited at 623 K, with a flow ratio ΦN2/ΦO2 of 1.25 and a total deposit time of 30 minutes grew preferentially oriented along the (111) plane of the zirconium oxyitride monoclinic phase. The SEM analyses showed that the films grew homogenously, and the AFM studies indicated that the average rugosity of the film was 5.9 nm and the average particle size was 150 nm. The analysis of the corrosion resistant, shows that the stainless steel coated with the film was increased a factor 10. Finally; through the analysis of the biocompatibility we established that the films have a better surface than the substrate (stainless steel 316 L) in terms of the adhesion and proliferation of bone cells.

New generation PVD coatings for industrial applications include the niobium nitride (NbN) due to its excellent properties such as high chemical inertness, excellent mechanical properties, high electrical conductivity, high melting point, and a superconducting transition temperature around 16 K. In this work we reported the results the study of corrosion and erosion effect on niobium nitride coatings deposited on AISI304 stainless steel using unbalanced and balanced magnetron sputtering and then it were compared to the uncoated tool steel substrate. The corrosion-erosion experiments were studied in a test machine varied the different velocities and impact angles of the erodent particles. The slurry used consists of quartz particles suspended in a mixture of 0.5 M sulphuric acid solution and 3.5% NaCl, whit cathodic protection. The film microstructure and chemical composition were analyzed by X-ray diffraction (XRD), cross-section scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results indicated that the erosion-corrosion resistance of the coated samples was found to be superior to that of the uncoated sample and the wearing mechanisms on the coating and the steel depending on the impact angle and the impact velocity of erodent particles. Possible reasons for such behavior are described in this paper.

En la nueva generación de recubrimientos de uso industrial se incluye el nitruro de niobio (NbN) debido a sus propiedades fisicoquímicas tales como: alta conductividad eléctrica, buenas propiedades mecánicas, alto punto de fusión e inercia química y además por ser un superconductor con temperatura crítica de 16 K. En este trabajo se reporta el efecto del sinergismo corrosión y erosión sobre recubrimientos de NbN depositados sobre acero inoxidable 304 y silicio usando los sistemas de sputtering con magnetrón balanceado y desbalanceado. Los experimentos de erosión-corrosión se estudiaron en un sistema que varió la velocidad y el ángulo de impacto de las partículas de erosión. Para ello se utilizó un lodo de partículas de SiO2 en una solución de 0,5M de H2SO4 + 3,5% NaCl y una concentración de 30% en peso de partículas de SiO2. La microestructura, morfología y composición química de las películas fueron analizadas con difracción de rayos X (DRX), microscopía electrónica de barrido (MEB) y espectroscopia de fotoelectrones generados por rayos X (EFRX), respectivamente. Los resultados muestran que la resistencia a la erosión-corrosión de los recubiertos de NbN fue superior al sustrato y los mecanismos de desgaste sobre el recubrimiento dependen del ángulo de impacto y la velocidad de las partículas de erosión. Posibles razones de este comportamiento son discutidas en este trabajo.

The aim of this research is to study the influence of the magnetic field configuration in a sputtering system on the mechanical properties of CrN, TaN, TiN, NbN and ZrN coatings. Different magnetic field configurations were quantified through the unbalance coefficient, K G , which is proportional to the zero field point in the magnetron. In this work, films were deposited in two magnetic field configurations, K G =1.3 and 0.825. The most important effect of the magnetic field configuration was observed on film hardness. When depositing on AISI M2 and 304 steels, mechanical properties and wear resistance were increased when increasing energy parameter; higher hardness was obtained for TaN, NbN and ZrN films. Another consequence of the change in the magnetic field was compressive residual stress variation. Higher variation was presented on TaN films while CrN films presented lower stress concentration.

El objetivo de esta investigación es estudiar la influencia de la configuración del campo magnético en un sistema de sputtering en las propiedades mecánicas de recubrimientos de CrN, TaN, TiN, NbN y ZrN. Se cuantificaron diferentes configuraciones del campo magnético a través del coeficiente de desbalanceo K G , que es proporcional al punto de campo cero en el magnetrón. En este trabajo de depositaron películas con dos configuraciones del campo magnético, K G =1.3 y 0.825. El efecto más importante de la configuración del campo magnético se observó en la dureza de la película. Al depositar sobre acero AISI M2 y acero 304, mejoraron las propiedades mecánicas y la resistencia al desgaste al aumentar el parámetro de energía; los valores de dureza más altos se obtuvieron para las películas de TaN, NbN y ZrN. Otra consecuencia del cambio en el campo magnético fue la variación en los esfuerzos residuales de compresión. La variación más alta se presentó en las películas de TaN mientras que las películas de CrN presentaron la menor concentración de esfuerzos.