A. Devia

Synthesis of Ti/TiN/TiCN coatings grown in graded form by sputtering dc

Graded coatings have the advantage of having gradual properties such as thermal expansion coefficient and lattice parameter, avoiding adherence problems due to good match between their component materials. In this work, some properties of coatings grown in graded form are presented. The materials were produced using the sputtering dc technique because of its facility to control the deposition parameters and generate homogeneous growth. The target is a disc of titanium and the samples are made of stainless steel 304. The working gases are argon, nitrogen and methane, which are mixed according to the material to be produced. Titatnium (Ti) layer is grown with argon, the titanium nitride (TiN) film is produced with a mixture of argon and nitrogen, and the titanium nitride carbon (TiCN) material is obtained mixing argon (Ar), nitrogen (N2) and methane (CH4). These materials are characterized with scanning probe microscopy (SPM) in atomic force microscopy (AFM) mode in order to determine grain size and with x-ray photoelectron spectroscopy (XPS) studying the chemical composition and performing depth profiles.

Study of TiC/a-C thin films growth by cathodic arc discharge varying the substrate temperature

TiC thin films were grown on 304 stainless steel substrates using the cathodic arc discharge (CAD) technique. Titanium (6N) was placed in the cathodic electrode and the substrate was placed on the anode, besides this electrode is a furnace. The substrate temperature was varied between 50 and 250 °C with increases of 50 °C. For producing the discharge, a critical damping RLC (C=0.54 mF, L=2.3 mH and R=0.46 mΩ) circuit was employed. To grow the TiC films, methane was used at a pressure of 3 mbar and a discharge voltage of 270 V. X-ray diffraction (XRD) showed the TiC-phase with broad peaks and low intensities, however, the films have a crystallographic texture coefficient for (111)-orientation. Using the Scherrer equation both the crystallite size and microstrain were determined. The crystallite size increased as a function of substrate temperature. Using x-ray photoelectron spectroscopy (XPS) technique, amorphous carbon and TiC were identified. Profiler depth was realized for identifying the distribution of both compounds in the film.

Electrical properties of AuN thin films

Gold nitride (AuN) is a recently synthesized component and is being studied for properties like optical, electrical and mechanical. Plasma-assisted physical vapor deposition (PAPVD) in pulsed arc system is used for deposition of AuN thin film. The system is formed of a reactor in which there are two faced electrodes, and a power-controlled system that performs the discharge systematically. Chemical analyses were realized by x-ray photoelectron spectroscopy (XPS) technique, and narrow N 1s and Au 4f spectra are shown using film stoichiometry, and I‐V curves were obtained in two ways (substrate‐film and film‐substrate), to observe the electrical properties.

Study of multilayer coatings of Ti/TiN/TiC produced by pulsed arc discharge

This work presents a study of multilayered Ti/TiN/TiC thin films obtained using a PAPVD (Plasma Assisted Physical Vapor Deposition) system by pulsed-arc discharge. For this purpose, a titanium target and a stainless steel substrate were used, placed on the cathode and on the anode, respectively, inside a vacuum chamber. To grow these films, different gases and concentrations were required. Ti is obtained with argon gas, TiN with nitrogen, and TiC with methane, at 2.5 mbar and 5 mm distance between electrodes. By means of X ray diffraction (XRD), the phases present in the film were determined, observing (111), (200), and (100) orientations for both, TiN and TiC. Also, by employing XRD techniques, Titanium Atoms Distance (DTA) was calculated at the interface of TiN and TiC, in order to study the crystallographic match. Energy Dispersive Spectroscopy (EDS) was employed in order to carry out elemental analyses in the materials. These analyses were obtained for 12 keV and 30 keV, observing the effects in the results. Taking advantage of defects generated during the growth of the multilayer, chemical composition maps were carried out, probing the combination of Ti and N in one layer and Ti and C in the other layer. Scanning Electron Microscopy (SEM) technique allowed observing the presence of the multilayer, as well as the measurement of the thicknesses of each layer, which are in the order of nanometers.

Effects of the Substrate Temperature in AuN Thin Films by Means of X‐Ray Diffraction

Gold is used in electronic industry like electric conductor for products such as computers, mobiles phones, etc; with the drawback that it is one of the most expensive metals in the market. Gold Nitride is a new material, having excellent physics properties like high hardness, high melting point, high electric conductivity, chemical inertia and good thermodynamic stabily among others. At the moment its study is more about electronics, optics, mechanical properties and growth of the films. AuN thin films were produced by the PAPVD (Plasma assisted Physics Vapor Deposition) method, using the pulsed arc technique in a mono-vaporizer system. These films were created with an Au target of 99% purity and deposited on stainless steel 304. It was observed that heating the substrate produces small stoichiometric changes in the film, which makes small changes in the diffraction patterns to appear, like widening in the Au orientation, since the composicional gradient is varying according to the substrate temperature. Au 4f and N1s narrow spectra were analyzed using XPS (X-Ray Photoelectron Spectroscopy), in order to observe stoichiometry in the films.

Chemical and morphological properties of (Ti-Zr)N thin films grown in an arc pulsed system

Due to its extensive field of application in different areas, including mechanics, electronics, tribology and optics the last decade has seen a large interest the study of titanium-zirconium-nitride (Ti-Zr)N thin films grown by different techniques. We had produced (Ti-Zr)N thin films and in this work chemical, morphological and electronics analysis are presented. Thin films were produced by the PAPVD (plasma assisted physics vapor deposition) technique, by pulsed arc in a mono-vaporizer system using a titanium-zirconium target with 99.99% purity. Argon-nitrogen mixture for the discharge was used. For the analyses X-ray photoelectron spectroscopy (XPS) and scanning probe microscopy (SPM) techniques were used, XPS results shown the chemical composition of the films. Films were morphologically and tribologically characterized using SPM, obtaining grain size and friction coefficient.

Study of W/WC Coatings Varying the Substrate Temperature

Tungsten carbide is considered a very important material used for industrial applications due to their high hardness. In this work the production of W/WC coatings used a repetitive pulsed arc system is employed. During the grown process, the substrate temperature is varied in order to identify the influence of this parameter in the structure, composition and morphology of the coatings. The layer of W is grown to improve the adherence of the WC material on the stainless steel 304. To grown the coatings, it was used a W target in the cathode. The gas of work is methane and as it is knew, to use a gas as precursor for WC production causes the apparition of different phases as WC and W2C. The power supply allows varying the active and passive time of pulses, which in this case have a value of 1 s. the coatings produced are characterized by X‐ray diffraction (XRD), X‐photoelectron spectroscopy (XPS) and scanning probe microscopy (SPM). All of these techniques allow determining properties such as chemical compo...

Deposition And Characterization of (Ti,Zr)N Thin Films Grown Through PAPVD By The Pulsed Arc Technique

The Plasma Assisted Physic Vapor Deposition (PAPVD) by the pulsed arc technique has been used for deposition of Titanium Zirconium Nitride (Ti,Zr)N coatings, using a segmented target of TiZr. The deposition was performed in a vacuum chamber with two faced electrodes (target and substrate) using nitrogen as working gas, and a power‐controlled source used to produce the arc discharges. Films were deposited on stainless steel 304, and they were characterized using the X‐Ray Photoelectron Spectroscopy (XPS), X‐Ray Diffraction (XRD), Energy Dispersion Spectroscopy (EDS) and Scanning Probe Microscopy (SPM) techniques. The XRD patterns show different planes in which the film grows. Through SPM, using Atomic Force Microscopy (AFM) and Lateral Force Microscopy (LFM) modes, a nanotribologic study of the thin film was made, determining hardness and friction coefficient.

Determination of temperature in an arc discharge plasma by using a double probe

In this work we report measurements of the electronic density and electronic temperature in a pulsed plasma system by using a double probe. We have implemented an automatic system of measure that start from the bias of a double electrostatic probe, allows us to register the complete curves of current-voltage in times of order of 10 ms; The electron density and electronic temperature can be extracted from the current-voltage I(V) characteristic. The advantage of this technique is that it allows us to get “in situ” quantity of information that when comparing them with the theoretical results using numeric methods for its simulation, provide us the necessary fits to quantify these parameters.

Hybrid studies of collisionless magnetic reconnection on tearing mode

In this work, we performed two-dimensional hybrid (kinetic particle ions, massless fluid electrons) studies of collisionless magnetic reconnection on tearing mode, which is characteristic of magnetosphere and high temperature fusion device plasmas. Results include the full electron pressure tensor (instead of a localized resistivity) in the generalized Ohms law to initiate reconnection, and an initial perturbation to the Harris equilibrium is applied. It was found that the reconnection rate has similar results to those obtained on magnetohydrodynamic (MHD) models and kinetic models.