The tribological behavior of Ni-based coatings was analyzed. The coatings were deposited on grey cast iron substrates in a spray and fuse process using Superjet Eutalloy deposition equipment, varying the oxygen flow conditions in the flame. By means of the X-ray diffraction (XRD) technique, the crystal structure of the coatings was determined. The XRD patterns show the crystalline phases with principal reflections for Ni in the planes (111) and (222). Crystalline properties such as the orientation coefficient, crystallite size, and macrostrain showed the relationship with tribological and mechanical properties such as the dry wear rate and the microhardness. The microhardness was analyzed on the surface and on cross sections of the coatings by means of a Knoop microhardness tester. The topography and the morphological characteristics of the coatings and the tribo-surfaces were exanimated using scanning electron microscopy (SEM) and confocal microscopy, while the chemical composition was measured by means of energy-dispersive X-ray spectroscopy (EDS). The tribological behavior of the coatings was examined via the scratch cohesion–adhesion test, using cross sections of the coatings. Furthermore, adhesion and abrasion wear tests were carried out, using the pin-on-disk method, under the ASTM G99 standard and the ASTM G65 standard, respectively. The wear rate of the coatings showed a strong relation to the porosity in the metal matrix, which was previously determined via electrochemical characterization techniques.

Low-carbon steel AISI 1020 was subjected to high-pressure torsion (HPT) with 6.0GPa pressure through 1/4–5 turns. The microstructures of the samples in each turn were studied by means of X-ray diffraction (XRD) analyzing the changes in micro-strain, crystallite size and lattice parameter. Vickers testing was utilized to study the microhardness behavior of the samples subjected to HPT processing. The morphology evolution of the samples and especially the changes in ferrite and pearlite structures were studied for different numbers of turns using scanning electron microscopy (SEM).

In this work, the effect of oxygen flow variation in the corrosion behavior of Ni-based WC/Co coatings deposited by spray and fuse process was investigated. The coatings were deposited on gray cast iron substrates using a Superjet Eutalloy thermal spraying gun. The morphology of the coatings was analyzed using scanning electron microscopy. The crystallographic phases were registered by x-ray diffraction (XRD), the diffraction patterns show the crystalline phases of the powder components with principal reflections for Ni and WC, the increase in flame temperature, due to the oxygen flow variation, generated amorphization in the nickel and an important crystallization of the planes (111) and (222) of WC as well as the decarburization of WC in W2C and W metallic. The corrosion behavior was investigated at room temperature in a 3.5% w/w aqueous solution of NaCl via potentiodynamic polarization. Electrochemical corrosion test showed that the coatings deposited under neutral flame conditions with an oxygen flow of 12.88 SCFH evidenced higher corrosion resistance. The chemical composition of the coatings and corrosion areas were analyzed by particle-induced x-ray emission, this technique permitting the corroboration of the decarburization process of WC determined by XRD and the formation of Cl structures.

(TiAl)N Films were grown on H13 steel by a plasma assisted repetitive pulsed arc discharge. To grow the coatings, a TiAl sintered cathode was used, 50% Ti-50% Al. The deposition system consists of a reaction chamber with two electrodes placed face to face. A pulsed power supply, which allows for control of parameters like time active arc, time between arcs, arc energy, and others, is used to generate the discharge. Thermal changes were carried out on H13 steel before and after growing the (TiAl)N films. X-ray diffraction (XRD) was employed to study the coatings, observing the H13 steel and (TiAl)N oxidation temperature. Morphological characteristics were analyzed by means of an Atomic Force Microscopy (AFM). Scanning electron microscopy (SEM) revealed the surface chemical composition of the films and morphological details of the samples. (C) 2007 Published by Elsevier Inc.

In this work the study of plasma characteristics by means of two of the most common techniques employed by the scientific community dedicated to the experimental plasma research is presented. The plasma was generated in a vacuum reaction chamber which was filled with hydrogen gas. Inside the chamber, two opposite electrodes were placed: the cathode, which was formed by a target of highly oriented pirolitic carbon and the anode. The electron temperature Te and the electron density ne were measured by using optical emission spectroscopy and electrostatic double probe, obtaining very close values for each case. Te was calculated as approximately 0.7eV and ne of the order of 1013cm−3. The optical emission measurement allows one to identify the substances that are in the plasma like C I, C II, C III, H I and H2 and some possible reactions. The double-probe technique showed the plasma potential of about 24V. The characteristic curve of the double probe exhibited oscillational plasma instabilities which could be attributed to the charge density variation or other factors, such as the employed AC signal and the geometric probe.

A study of materials used in the molds production to aluminium rims manufacture in the MADEAL S.A. factory was carried out for apply a plasma assisted surface treatment consists in growing TiAlN hard coatings that it protects this molds in the productive process. This coating resists high oxidation temperatures, of the other of 800 degrees C-[1,C-2], high hardness (2800 Vickers) and low friction coefficient ([3]). A plasma assisted repetitive pulsed arcs mono-evaporator system was used in the grow of the TiAlN coatings, the TiAlN target is a sinterized 50% Ti and 50% Al, in the substrate they were used two types of steel that compose the molds injection pieces for the rims production. These materials were subjected to linear and fluctuating thermal changes in the Bruker axs X-Ray diffractometer temperature chamber, what simulated the molds thermal variation in the rims production process and they were compared with TiAlN coatings subjected to same thermal changes. The Materials characterization, before and later of thermal process, was carried out using XRD, SPM and EDS techniques, to analyze the crystallographic, topographic and chemical surface structure behaviours.

ZrN films were grown by a plasma-assisted repetitive pulsed vacuum arc discharge. The films were grown on 304 stainless steel substrates. To grow the coatings, a cathode of Zr was used. The system is made up by a reaction chamber with two electrodes placed face to face. A pulsed power supply is used to generate the discharge. The coatings were grown, varying the substrate temperature (Ts) between 50°C and 260°C. The pressure into the chamber was 3mbar and the voltage of the discharge was 270V. XRD technique was employed to study the coatings, observing variations of some parameters as crystallographic texture and crystallite size, as a function of Ts. Morphological characteristics were analyzed by means of an atomic force microscopy (AFM), determining the thickness and the grain size, where it is possible to observe the influence of the surface and strain energies which have great relationship with Ts.

ZrN films were grown by the PAPVD method in the pulsed arc technique; bilayers were grown on stainless steel substrates by using a repetitive pulsed vacuum arc system. To produce the coatings, a target of Zr with a purity of 99.99% was used. The system is composed by a reaction chamber with two opposite electrodes placed inside it. The target is the cathode and the samples of stainless steel are the anode. A pulsed power supply is used to generate the discharge. The coatings were grown, varying the temperature of the substrate between 50 degrees C and 260 degrees C. The pressure into chamber was 3 mbar and the voltage of the discharge was 270 V. XRD technique was employed to study the coatings, observing changes on the lattice paramenter and intensity variations of the crystallographic planes, as a function of the substrate temperature. Morphological characteristics were analized by means of an Atomic Force Microscopy (AFM), determining the thickness and the grain size. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Por medio de espectroscopia optica de emision, se estudio un plasma utilizado en la produccion de recudimientos de TiO2. El sistema esta compuesto por una camara de vacio dentro de la cual se ubican los electrodos conformados por el material del blanco (titanio) y el sustrato (vidrio). La presion de trabajo fue de 1.7 mbar. en ambiente de oxigeno y el voltaje de la descarga fue de 300 V. estos espectros fueron tomados en un rango entre 250 y 800 nm. Se realizo una identificacion de las sustancias que se formaron en el plasma. Despues de identificar las diferentes transiciones, se procedio al calculo de la temperatura y la densidad del plasma, utilizando la relacion entre linea - continuo y entre lineas de diferente grado de ionizacion.