<p>The changes in the microstructure, mechanical properties and residual stresses of AlTiN, AlTiSiN, AlCrN and AlCrSiN coatings, has been studied before and after annealing at 900 ºC and 1100 ºC, using scanning and transmission electron microscopy, along with nano-indentation and X-ray diffraction techniques. The As-deposited coatings show a columnar structure, with a crystallite size between 18 nm and 28 nm. Despite the silicon addition, no effect on the crystallite size refinement was observed.<br />However, the addition of silicon increases hardness, elastic modulus and compressive residual stresses. After annealing at 900 ºC, the crystallite size growth and the residual stress relaxes; therefore, the coating hardness decreases. At 1100 ºC, the oxide layers formed in AlTiN and AlTiSiN, which act as protective layers enhancing oxidation resistance; meanwhile, a complete oxidation of AlCrN and AlCrSiN coatings take place. The Titanium based coatings present some superior mechanical properties and oxidation resistance than the chromium based coatings at 900 ºC and 1100 ºC.</p>

Se llevó a cabo un análisis exhaustivo del comportamiento elastoplástico de láminas de hierro ARMCO sometidas a deformación plástica severa (SPD) mediante la técnica de presión calibrada restringida (CGP) por medio del método de elementos finitos (FEM). Se consideraron parámetros como la geometría de la matriz y el coeficiente de fricción para estudiar sus efectos en la respuesta elasto-plástica del material. Para ello se utilizó ANSYS workbench para las simulaciones por elementos finitos. Los resultados mostraron que los parámetros estudiados influyen de forma diferente no sólo en la deformación alcanzada sino también en la distribución de la deformación a través de la lámina.

La proyección térmica es una técnica desarrollada inicialmente para hacer recubrimientos metálicos sobre estructuras metálicas, sin embargo, debido a la necesidad creciente de proteger piezas sometidas a ambientes de trabajo agresivos, ya sea por las condiciones de trabajo o por fenómenos ambientales, hoy en día se hacen recubrimientos de metales, cerámicos, polímeros y combinaciones de estos, con excelentes resultados para proteger estructuras y reducir costos de mantenimiento.

Cu-Be alloys are considered high strength alloys when containing 0.2% to 2% of Be per weight, 0.2% to 2.7% of Co per weight, and up to 2.2% of Ni per weight, since they can present an elastic limit higher than 1380 MPa after aging (precipitation hardening), while, without heat treatment, they present an elastic limit between 205 MPa and 690 MPa [1]. Therefore, the complexity of the microstructure is a determining factor in the mechanical behavior of this type of alloys. In this work we analyzed the effect of microstructural variations obtained by cooling with water and with air from three different solubilization temperatures (750 °C, 800 °C and 850 °C) during 1 h, with and without aging, on the abrasive wear behavior of the Cu-1.9Be-0.25(Co+Ni) alloy. The chemical and microstructural characterization was performed by Dispersive Energy X-Ray Fluorescence (EDXRF) and Scanning Electron Microscopy (SEM-EDS), respectively. Abrasive wear behavior was evaluated under the guidelines of ASTM G65-16. Procedure E was used in this study, and the applied parameters were: force against the specimen (130 N), wheel revolutions (1000 rpm), linear abrasion (718 m) and test time (5 min). All tests were done in duplicate, showing a significant improvement in the abrasive wear behavior of the alloy, compared to the material in supply condition (T6). The lowest wear rates (<0.3 g/min) and volumetric loss (<200 mm3) were obtained with the specimens in solubilized condition with water cooling and without aging. The wear coefficients for the specimens with the highest resistance to abrasive wear are less than Ks=7x10-3.

This study investigated the mechanical properties and performance of μ-AlTiN coating deposited by PVD cathodic arc technique for a specific Al0, 67Ti0, 33N composition deposited on a WC-Co and AISI D2 steel substrate. The structure of the coating was analysed using SEM, EDAX, XRD, AFM and TEM. Nano indentation measurements were used for analysing mechanical properties; the coating’s performance was evaluated during the milling of a titanium alloy (Ti6Al4V). The TiN film was initially deposited to improve adhesion between coating and substrate, where columnar grains ranging in size from 200 to 500 nm were observed having NaCl-type structure. μ-AlTiN grain growth was also columnar but had ~50 nm grain size. The μ-AlTiN coated tool life was compared to an uncoated tool to determine the coating’s influence during Ti6Al4V milling. The μ-AlTiN coating improved tool life by 100% compared to that of an uncoated tool due to aluminium oxide and TiC formation on the surface and a decrease in friction coefficient between the chip and the tool.