Mejoramiento de las propiedades mecánicas y tribológicas del acero AISI 4340 tratado térmicamente, utilizando un recubrimiento de multicapas de TiN/TiAlN

RESUMEN: Multicapas de TiN/TiAlN (nitruro de titanio/nitruro de titanio aluminio) se depositaron por la técnica de la pulverización catódica d.c. reactiva utilizando blancos de titanio y de aluminio de 10 cm de diámetro, con una pureza de 99,9%, en una atmósfera de argón y nitrógeno (Ar/N), aplicando una temperatura de 300°C y una presión de 7x10-3 mbar al sustrato. Como sustratos se utilizaron silicio (100) y acero AISI 4340 tratado térmicamente con una dureza de 54 Rockwell C (HRC, aproximadamente 5,4 GPa). Recubrimientos de TiN/TiAlN con un contenido de Al de 70% y un espesor total de 4 µm se investigaron en función del número de multicapas y sus propiedades mecá- nicas y tribológicas se compararon con las de las muestras de acero sin recubrir. La estructura cristalina de las muestras recubiertas se analizó mediante difracción de rayos X, la morfología y topografía con microscopia electrónica de barrido (SEM) y microscopia de fuerza atómica (AFM). La dureza se determinó mediante nanoindentación, mientras que la resistencia al desgaste se caracterizó a través de mediciones de pin on disc. Para las 150 multicapas de TiN/TiAlN se obtuvo un incremento en la dureza y en el módulo de Young de 62% y 70% respectivamente, en relación a las 30 bicapas iniciales, y de 740% y 202% respectivamente, comparado con el acero AISI 4340 sin recubrir. Finalmente, el coeficiente de fricción se redujo de 0,55 a 0,20 y la rugosidad de 60 nm a 3,2 nm para las probetas de acero recubiertas con 150 bicapas de TiN/TiAlN, lo cual condujo a una mayor resistencia al desgaste del sistema de recubrimiento.ABSTRACT: TiN/TiAlN (titanium nitride/titanium aluminum nitride) multilayer were deposited by d.c. reactive magnetron sputtering using titanium and aluminum targets with 10 cm in diameter and 99.9% purity in an argon/nitrogen (Ar/N) atmosphere, applying a substrate temperature of 300°C and a pressure of 7x10-3 mbar. Silicon (100) and heat treated AISI 4340 steel samples with a hardness of 54 Rockwell C (HRC, approximately 5.4 GPa) were utilized as substrate. TiN/TiAlN coatings with 70% aluminum and 4 µm total thickness were investigated as function of multilayer number and their mechanical and tribological properties compared to the uncoated steel samples. The crystalline structure of the coated samples was analyzed through X-ray diffractometry and its morphology and topography using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Hardness was determined by means of nanoindentation, while wear resistance was characterized through pin on disc measurements. A hardness and Young Modulus increment from 62% and 70% respectively, were obtained for 150 multilayer of TiN/TiAlN related to 30 bilayers and from 740% and 202% respectively, compared with the uncoated AISI 4340 steel samples. Finally the friction coefficient was reduced from 0.55 down to 0.20 and the roughness from 63 nm to 3.2 nm for the steel samples coated with 150 bilayers of TiN/TiAlN, what conduced to a greater wear resistance of the coating system

Optical and tribo-mechanical characterization in metal-ceramic multilayers coatings

Laboratory scale studies of tribological properties of nitride coatings are useful in predicting their protective wear behavior in cutting toolsfor industrial-scale applications. The main aim of this research is to determine optical and tribo-mechanical properties in multilayer coatingsof metal-ceramic assigned as coatings A and B. These coatings were deposited by DC magnetron sputtering on carbon steel AISI 1060using buffer adhesion layers of W, Ti/W/WN and TiN/TiN respectively. For to determine molecules, interactions of materials were analyzedthrough of Raman and FTR spectroscopies. The nanohardness, tribological and adhesion behavior were studied by nanoindentation, pinon disk and a tribometer. The hardness and behavior tribological, were obtained by Nano-indentation, pin on disk, and scratch test using atribometer. FTIR and Raman analysis shown the formation of Ti metallic ion and WO3mainly in both coatings. The hardness of coatingsshown a slight improvement compared with the substrate. However, for industrial applications this property should be increase. The behaviorof COF does not present improvement. The mass loss and wear rate were high significantly due to the formation of cracks on surface coatings.Scratch analysis, it found three wear mechanics determined by the presence of irregular borders with sharp shadow, semicircle detachmentin coatings and coatings detachment in the central track as the load increase

Tribological properties and corrosion resistance enhancement of H13 hot work steel by means of CrN/TiN multilayers

ABSTRACT: Steel AISI H13 is used mainly for fabrication of hardened hot work tools; however life time of this steel is limited by its relatively low wear and corrosion resistance, if it would be exposed to an aggressive environment. It is widely known that the performance of tools and parts that undergo high mechanical load can be enhanced by the use of monolayer hard thin coatings. However, the use of such coatings as corrosion barriers is often unsatisfactory, since the deposition processes usually generate small pores and pinholes, which negatively affect the electrochemical behaviour of the coating/substrate system. On the other hand, if a hard thin film covers a less noble material, such as steel, small anodic areas could be generated and exposed to an aggressive environment a galvanic corrosion would take place. Therefore, it is also necessary to optimize the design of the coating system used in order to achieve the better relationship between mechanical and electrochemical properties for the whole system. The intention of the presented work was to enhance the tribological properties and corrosion resistance of steel AISI H13 through the use of a CrN/TiN multilayer coatings system, which were deposited by using the balanced magnetron sputtering technique

Análisis estructural y morfológico de películas de nitruro de aluminio obtenidas por deposición de láser pulsado

This paper gives the preliminary results about aluminum nitride (AlN) nanoestructured films deposited by pulsed laser deposition (PLD) technique, by using laser Nd:YAG (λ=1064), which hit a target of high purity aluminum (4N) in a nitrogen atmosphere. We used glass slide, Si 3 N4 (100) and Si (100) as substrates. The deposition time was 15 minutes at laser fluence 7 J/cm2 and room temperature. The thicknesses of thin films were 50 nm measured with a profilometer. The influence of nitrogen on thin films was studied by changing room gas pressure between 3 and 4 mTorr. Also we have studied the influence of substrate on morphological properties of AlN thin films. The film nanostructure was determined by scanning electron microscopy (SEM), atomic force microscopy (AFM) –the chemical composition– using the technique of energy dispersive X-ray (EDX). The crystal structure was examined with X-Ray Diffraction (XRD) to a 4 mTorr film on a Si3 N4 (100) substrate giving a polycrystalline structure with reflections of planes (002), linked to the wurtzite-like structure of AlN.En este trabajo, se presentan los resultados preliminares de películas nanoestructuradas de nitruro de aluminio (AlN), que fueron depositadas con el método de deposición por láser pulsado (PLD). Al efecto, se utilizó un láser Nd:YAG (¿=1064nm), que impacto un blanco de aluminio de alta pureza (4N), en una atmósfera de nitrógeno. Se utilizaron como sustratos portaobjetos de vidrio, Si3N4 (100) y Si (100). El tiempo de deposición fue de 15 minutos a una fluencia del láser 7 J/cm2 y a temperatura ambiente. El espesor de las películas fue de 50 nm medido con un perfilómetro. Para estudiar la influencia del nitrógeno en las películas delgadas de AlN, se varió la presión del gas ambiente entre (3 y 4) mTorr. Igualmente se estudió la influencia del sustrato en las propiedades morfológicas de las películas delgadas de AlN. La nanoestructura de las películas se determinó mediante microscopia electrónica de barrido (SEM), y microscopia de fuerza atómica (AFM); la composición química, utilizando la técnica de espectroscopía de rayos X por dispersión de energía (EDX). La estructura cristalina fue estudiada con difracción de rayos X (DRX), para la película de 4 mTorr sobre un sustrato de Si3N4 (100), y se encontró una estructura policristalina con reflexiones de los planos (002), asociados a la estructura tipo wurtzita del AlN

Performance of WC- inserts coated with nanometric [TiN/TiAlN]n - multilayer for the cutting processing of hardened AISI 4340 steel

RESUMEN: En el presente trabajo se muestran los resultados de la resistencia al desgaste de insertos de carburo de tungsteno (WC) sin recubrir y recubiertos con multinanocapas de [TiN/TiAlN]n con un espesor total promedio del recubrimiento de 4 μm, así como de insertos recubiertos con monocapas comerciales de TiCN-Al2O3-TiN (TINAL). Se realizaron ensayos de vida útil, análisis de temperatura en la zona de corte, mediciones de rugosidad superfi cial sobre la pieza y sobre los insertos en la superfi cie de ataque, análisis de huella de contacto entre viruta-insertos y análisis de composición química (EDS). Los ensayos se realizaron sobre piezas de acero AISI 4340 utilizando régimen de corte de acabado y aplicando altas velocidades de corte (HSC). Los resultados de mecanizado de acero, para un recorrido de 8.000 metros con diferentes insertos de carburo de tungsteno (WC), sin recubrimiento y recubiertos presentaron valores de desgaste de 0,117 mm y 0,138 mm; en relación a los insertos recubiertos con 300 y 200 bicapas de TiN/TiAlN, respectivamente. De igual manera, los insertos recubiertos con TINAL exhibieron valores de desgaste de 0,174 mm. Además, los valores de temperatura en la zona de corte y para una velocidad de corte de 176,6 m/mim fueron de 522,6 o C para los recubrimientos con 300 bicapas, de 721,4 o C para aquellos con 200 bicapas, y de 1.327,6 o C para los insertos recubiertos con TINAL. La disminución de la temperatura en la zona de corte, relacionada con un menor coefi ciente de fricción y una menor fuerza de corte, contribuyeron al alargamiento de la vida útil de los insertos.ABSTRACT: In the present work wear resistance of 4 μm uncoated tungsten carbide inserts (WC) and coated with [TiN/TiAlN]n multinanolayered or with commercial TiCN-Al2O3-TiN monolayers (TINAL) are examined. Life tests, cutting area temperature analysis, surface roughness measurements on work pieces, roughness measurements on the attacked surface, contact track analysis between chip-insert and chemical composition analysis (EDS) were carried out. Mechanical tests were conducted on AISI 4340 steel parts using cutting regime and applying high speed cutting (HSC). Machining results showed that for a distance of 8,000 m the inserts coated with 300 bilayers exhibited wear values of 0.117 mm, inserts coated with 200 bilayers showed values of 0.138 mm and those coated with TINAL presented wear values of 0.174 mm. Moreover, the temperature values for cutting speed at 176.6 m/mim for 300 bilayers was 522.6 o C, for 200 bilayers was 721.4 o C and 1,327.6 o C for inserts coated with TINAL. Lower temperatures, caused by a lower friction coeffi cient and cutting force, contribute to life-time increasing at WC inserts

Corrosion resistance improvement of steel AISI 4140 by using a titanium/titanium nitride multilayer coating system

RESUMEN: El acero 4140 se utiliza ampliamente en la fabricación de partes de máquinas con durezas entre 25-35 Rockwell C. Sin embargo, su vida útil se ve limitada por su baja resistencia al desgaste y a la corrosión. Con el fin de mejorar su comportamiento frente a la corrosión se depositaron multicapas de Titanio/Nitruro de Titanio (Ti/TiN) sobre substratos de acero 4140 mediante un sistema multi-blanco d.c. magnetrón sputtering a partir de un blanco de Ti de alta pureza (99,99%) en una atmósfera de Ar/N2. Con el objeto de estudiar el efecto del número de capas sobre la velocidad de corrosión de las películas depositadas, se crecieron multicapas con 1, 5, 10, 15, y 20 bicapas de [Ti /TiN], manteniendo un espesor total constante de 3 µm en todas ellas. Las fases existentes y composición química de los recubrimientos fueron analizados mediante espectroscopía de difracción de rayos X (XRD) y espectroscopía de energía dispersiva de rayos X (EDX) respectivamente. Las muestras de acero sin y con recubrimiento se caracterizaron además por Espectroscopía de Impedancia Electroquímica (EIS) y curvas de polarización Tafel. Se encontró que la velocidad de corrosión tuvo una disminución alrededor del 87% en el acero recubierto con 20 bicapas de Ti/TiN en comparación al acero sin recubrir y del 25% respecto a la muestra recubierta con 1 bicapa, lo cual evidencia el efecto positivo del incremento del período en las películas delgadas basadas en multicapas de Ti/TiN.ABSTRACT: Steel 4140 is widely used for fabrication of machines components with hardness between 25 and 35 Rockwell C (HRC). However, life time of this steel is limited by its low wear and corrosion resistance. In order to enhance its corrosion behavior, multilayer of Ti/TiN were deposited onto 4140 steel samples by d.c. reactive magnetron sputtering using a high purity titanium target (99.9) in an Ar/N2 atmosphere. With the purpose to study the influence of the layer number on the rate of corrosion of deposited films, multilayer of [Ti /TiN] were growth with 1, 5, 10, 15 and 20 bilayers and a 3 µm constant thickness for all samples. The grown phases and chemical composition were analyzed by x-ray diffraction spectroscopy (XRD), and energy dispersive X-ray spectroscopy (EDX) respectively. Additionally, the uncoated and coated steel samples were characterized using electrochemical impedance spectroscopy (EIS) and Tafel’s polarisation curves. A corrosion rate reduction of approximately 87% was found for the steel sample coated with 20 bilayers of Ti/TiN compared with the uncoated, and of 25% related to the sample coated with 1 bilayer. This evidences the positive effect of the period increase of the multilayered Ti/TiN thin films on their corrosion resistance

Evaluation of the influence of bias voltage on the corrosion resistance of AlNbN thin films

RESUMEN: Se depositaron películas delgadas de Nitruro de Niobio (NbN) y Nitruro de Niobio Aluminio (AlNbN) sobre sustratos de silicio (100) y de acero AISI 4140 mediante un sistema multiblanco magnetrón sputtering con r.f. (13.56 MHz), a partir de blancos de Nb y de Al de alta pureza (99.99%) en una atmósfera de Ar/N2, para diferentes voltajes de polarización del sustrato, con el fin de estudiar su efecto sobre la estructura cristalina y las propiedades electroquímicas. El acero 4140 se utiliza ampliamente en la fabricación de partes de máquinas con durezas entre 2535 Rockwell C, pero presenta la desventaja de que su vida útil se ve limitada por su baja resistencia al desgaste y a la corrosión. El patrón de XRD muestra de manera predominante los picos de Bragg de los planos (200) de la fase FCC del AlNbN, (200) de la fase hexagonal δ’NbN y (200) de la fase hexagonal del AlN. Mediante análisis de FTIR se pudo determinar los modos activos asociados a los enlaces NbN, AlN y AlNbN. Se caracterizaron muestras de acero AISI 4140 con y sin recubrimiento de AlNbN mediante Espectroscopía de Impedancia Electroquímica (EIS) y curvas de polarización Tafel. Se encontró una dependencia del voltaje de polarización sobre velocidad de corrosión para películas de AlNbN.ABSTARCT: Niobium Nitride (NbN) and Aluminum Niobium Nitride (AlNbN) thin films were deposited on silicon (100) and steel AISI 4140 substrates through a multitarget r.f. (13.56 MHz) magnetron sputtering system. The target where made using 4N purity Nb and Al and the growth was performed under a gas mixture of Ar/N2, for different substrate polarization voltages, in order to study the effect of polarization voltage on the crystalline structure and electrochemical properties. Steel 4140 is widely used for fabrication of machines components with hardness between 28 and 38 Rockwell C, however life time of this steel is limited by its low wear and corrosion resistance. The XRD pattern of the sample showed predominantly Bragg peaks for the planes (200) corresponding to FCC phase of the AlNbN, hexagonalδ' NbN phase and hexagonal AlN phase. The FTIR analysis showed vibrational modes associated with NbN, AlN and AlNbN bounds. The steel AISI 4140 with and without AlNbN coating were characterized through electrochemical impedance spectroscopy (EIS) and Tafel polarization curves. As a result of this work it was found a voltage polarization dependence on speed corrosion for NbN and AlNbN films

Nature in corrosion–erosion surface for [TiN/TiAlN]n nanometric multilayers growth on AISI 1045 steel

xxxxxThe aim of this work is to characterize the electrochemical behavior of [TiN/TiAlN]n multilayer coatings under corrosion–erosion condition. The multilayers with bilayer numbers (n) of 2, 6, 12, and 24 and/or bilayer period (Λ) of 1500 nm, 500 nm, 250 nm, 150 nm and 125 nm were deposited by magnetron sputtering technique on Si (100) and AISI 1045 steel substrates. Both, the TiN and the TiAlN structures for multilayer coatings were evaluated via X-ray diffraction analysis. Mechanical and tribological properties were evaluated via nanoindentation measurements and scratch test respectively. Silica particles were used as abrasive material on corrosion–erosion test in 0.5 M of H2SO4 solution at impact angles of 30° and 90° over surface. The electrochemical characterization was carried out using polarization resistance technique (Tafel), in order to observe changes in corrosion rate as a function of the bilayer number (n) or the bilayer period (Λ) and the impact angle. Corrosion rate values of 9115 μm y for uncoated steel substrate and 2615 μm y for substrate coated with n = 24 (Λ = 125 nm) under an impact angle of 30° were found. On the other hand, for an impact angle of 90° the corrosion rate exhibited 16401 μm y for uncoated steel substrate and 5331 μm y for substrate coated with n = 24 (Λ = 125 nm). This behavior was correlated with the curves of mass loss for both coated samples and the surface damage was analyzed via scanning electron microscopy images for the two different impact angles. These results indicate that TiN/TiAlN multilayer coatings deposited on AISI 1045 steel represent a practical solution for applications in corrosive–erosive environmen

AlN film deposition as a semiconductor device

AlN films were deposited by pulsed laser deposition (PLD) using an Nd: YAG laser (ë = 1064 nm). The films were deposited in a nitrogen atmosphere as working gas; the cathode was an aluminium high purity (99.99%) target. The films were deposited using 7 J/cm2 laser fluence for 10 minutes on silicon (100) substrates. The working pressure was 9x10-3 mbar and the substrate temperature was varied from 200°C to 630°C. The thickness measured by profilometer was 150 nm for all films. Moreover, surface acoustic wave (SAW) devices with a Mo/AlN/Si configuration have been fabricated using AlN-buffer and Mo Channel. The films' morphology and composition were studied using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), respectively. The films' optical reflectance spectra and colour coordinates were obtained by optical spectral reflectometry in the 400-900 cm-1 range using an Ocean Optics 2000 spectrophotometer. The present work found clear dependence on morphological properties, reflectance, dominant wavelength colour purity, frequency response and acoustic wave speed in terms of the temperature applied to the substrate. About 30% reduction in reflectance was observed and increased acoustic wave speed of about 1.3 % when the temperature was increased from 200°C to 630°C.Películas de AlN fueron depositados por la técnica de deposición por láser pulsado (PLD), utilizando un láser Nd: YAG con una longitud de onda de 1064 nm. Las películas fueron depositadas en una atmósfera de nitrógeno como gas de trabajo; como cátodo se usó aluminio de alta pureza (99,99%). Las películas fueron depositadas con una fluencia del láser de 2,28 J/cm2 durante 10 minutos sobre sustratos de silicio (100). La presión de trabajo fue de 9 x 10-3 mbar y la temperatura del sustrato se varió desde 200 °C a 630 °C. El espesor medido por perfilometría fue de 150 nm para todas las películas. Además se fabricaron los dispositivos de ondas acústicas de superficie (SAW) con una configuración Mo/AlN/Si, empleando AlN-bufer y un canal de Mo. La morfología y la composición de las películas se estudiaron mediante microscopía electrónica de barrido (MEB) y energía dispersiva de rayos X de análisis (EDX), respectivamente. Los espectros de reflectancia óptica y color de coordenadas de las películas se obtuvieron por la técnica óptica reflectometría espectral en el rango de 400-900 cm-1 por medio de un espectrofotómetro Ocean Optics 2000. En este trabajo se encontró una clara dependencia de las propiedades morfológicas, reflectancia, pureza dominante, longitud de onda del color, la respuesta de frecuencia y velocidad de la onda acústica en términos de la temperatura aplicada al sustrato. Se observó una reducción en la reflectancia de aproximadamente 30% y aumento de velocidad de la onda acústica de aproximadamente 1,3% cuando la temperatura se incrementó desde 200 °C a 630 °C

Structural, mechanical and tribological behavior of TiCN, CrAlN and BCN coatings in lubricated and non-lubricated environments in manufactured devices

This paper presents the structural, mechanical and tribological behaviors for AISI 1045 steel uncoated and coated with Titanium Carbo-nitride (TiCN), Aluminum Chrome Nitride (CrAlN) and Boron Carbo-nitride (BCN) under lubricated and non-lubricated environments. The coating's natural effect on the crystalline structure, chemical composition, as well as the mechanical properties were determined by X-ray diffraction (XRD), X-ray photo-electron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), nanoindentation and tribological characterization techniques. The results show that the material with the lowest elastic modulus was TiCN (224 GPa), followed by CrAlN (235 GPa), and the BCN (251 GPa). The friction coefficient results for the coatings without lubrication were 0.74, 0.66 and 0.60, respectively, and with lubrication were 0.24, 0.23 and 0.21, respectively. These results indicate that the tribological properties are strongly dependent on the lubricated environment's nature and the coating's nature. Advanced surface treatments are increasingly used in the daily manufacture of parts for the metalworking and automotive industry due to high mechanical and tribological requirements; therefore, TiCN, CrAlN and BCN coatings can be used as future materials for elements subject to high stress and wear in lubricated environment