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In this research, the synthesis of Co–Fe–Ni ternary alloys in different compositions (Co40Fe30Ni30, Co30Fe40Ni30 and Co30Fe30Ni40), and their structural and magnetic properties were assessed. These alloys were milled during 7 h by mechanical alloying (MA), after of the milling time, the results of the structural analysis, shown three solids solutions obtained with fcc-structure (Co(FeNi)–fcc, Fe(CoNi)–fcc and Ni(FeCo)–fcc). As a consequence of the process of synthesis, the crystal size refinement was observed in all cases, meanwhile, the particle size increased due to the powders ductility. The magnetic properties at room temperature were studied to observe the saturation magnetization (Ms), before and after of the milling, the results of the un-milled powders were 140, 130 and 110 A m2/kg for Co40Fe30Ni30, Co30Fe40Ni30 and Co30Fe30Ni40 respectively, after of mechanical alloying, the MS increased to 162, 166 and 150 A m2/kg. On the other hand, the coercive field (HC) values decreased drastically from 6.13 kA/m (~77 Oe), 4.77 kA/m (~60 Oe) and 5.57 kA/m (~70 Oe) before of the milling process, to 0.365 kA/m (~4.6 Oe), 0.296 kA/m (~3.7 Oe) and 0.306 kA/m (~3.8 Oe) after the milling for Co40Fe30Ni30, Co30Fe40Ni30 and Co30Fe30Ni40, respectively.

In this work, a novel combination of designed heat treatments and cold work performed on Al-6063 alloy was proposed. The consumption of aluminium and its alloys in the automotive and aeronautic industries has increased over the past few years, in the same way, as the consumption of material for manufacturing moulds for casting of plastic parts and dies for plastics and metals. Then, it is important to find a low-cost alternative to maximise the mechanical properties of aluminium, with a negligible effect on the ductility of the alloy, which is important due to thermal and mechanical fatigue on mould and dies. It is well known that precipitation hardening increases the mechanical and yield strength of aluminium alloys with a major ductility loss. However, the developed methodology consists of a solution heat treatment, followed by cold working (strain hardening), and lastly a heat treatment (precipitation hardening and stress reliever) to produce Al 6063 aluminium alloys with enhanced mechanical strength and with a negligible ductility loss. The proposed methodology increases around 23.45% of the tensile and yield strength, with a ductility reduction of less than 1.5% in the elastic materials region. The experimental tensile testing results are correlated with nanoindentation experimental results in order to confirm that the level of cold working is directly proportional to mechanical strength levels by two different characterisation techniques at a macro- and nanoscales, respectively.

This research aimed to obtain a C-based coating electrochemically applied on an AA6063 alloy. Two electrochemical cells were designed and manufactured to obtain the C-based coating film on flat and cylindrical samples. Structural and microstructural characterizations were performed along with fatigue and corrosion performance testing. The structural and microstructural characterization revealed that the C-based coating deposited on AA6063 corresponded to carbon nanofibers and/or polycrystalline graphite. The performance testing showed an increase in fatigue life along with a decrease in corrosion resistance. The fracture surfaces of the fatigued samples were inspected by Scanning Electron Microscopy and 3D optical microscopy to correlate them with fatigue life estimation. The aforementioned process is a step towards the future development of a complete coating system that will overcome corrosion susceptibility. The carbon film obtained by this electrochemical route has not previously been reported elsewhere.

In this research work, a preliminary potentiodynamic polarization performance testing was carried out on a new environmentally friendly proposed composite coating. The proposed composite coating was developed by: (a) hot sulfuric anodizing to produce an Al2O3 conversion film followed by an (b) organic electrodeposited chitosan&ndash, sodium alginate blended film. Posteriorly, the conversion and organic films were microstructurally characterized by scanning electron microscopy. Finally, the polarization resistance technique was used to measure the corrosion resistance of the uncoated and coated AA6063 alloy in a simulated marine environment and the polarization tests were compared to samples immersed during 30 days in same electrolyte solution. The obtained inhibition corrosion efficiency of the proposed coating system was measured comparing the Rp of the uncoated alloy to the coated samples, showing an efficiency about 99% for a 3% NaCl electrolyte for some of the samples. Therefore, the experimental results obtained during this research demonstrates the feasibility of using the developed anticorrosive composite coating to protect aluminum alloys against chloride corrosive ions species and to further continue with the corresponding research.

In this work, an alternative statistical multiple linear robust regression methodology was used to analyze the experimental data obtained from tensile tests performed on heat treated samples of an aluminium 6063 alloy. The proposed methodology allows the identification of empirical relations between the ageing temperature and process time with the mechanical strength (UTS) and yield point (YS) of the alloy. Through these empirical relationships: a) $$ UTS=0.0932{T}_a{t}_A-0.1356{t}_A^2-0.0002434{T}_a^2{t}_A+0.00063{t}_A^3 $$ and b) $$ YS=5.10{T}_a-20.32{t}_A-0.05281{T}_a^2+0.2297{T}_a{t}_A+0.0001459{T}_a^3-0.0006192{T}_a^2{t}_A $$ , obtained by using the multiple linear robust regression methodology, it was possible to find that an ageing temperature of 192 °C for 120 min would produce the maximum strength levels for the Al-6063 alloy. For such alloy, empirical relationships were successfully determined for ageing heat treatment design.

The present research deals with the comparative wear behavior of a mechanically milled Al-6061 alloy and the same alloy reinforced with 5 wt.% of Al2O3 nanoparticles (Al-6061-Al2O3) under different dry sliding conditions. For this purpose, an aluminum-silicon-based material was synthesized by high-energy mechanical alloying, cold consolidated, and sintered under pressureless and vacuum conditions. The mechanical behavior was evaluated by sliding wear and microhardness tests. The structural characterization was carried out by X-ray diffraction and scanning electron microscopy. Results showed a clear wear resistance improvement in the aluminum matrix composite (Al-6061-Al2O3) in comparison with the Al-6061 alloy since nanoparticles act as a third hard body against wear. This behavior is attributed to the significant increment in hardness on the reinforced material, whose strengthening mechanisms mainly lie in a nanometric size and homogeneous dispersion of particles offering an effective load transfer from the matrix to the reinforcement. Discussion of the wear performance was in terms of a protective thin film oxide formation, where protective behavior decreases as a function of the sliding speed.

The effects of Manganese doped (Bi 1/2 Na 1/2 )TiO 3 and (Bi 1/2 Na 1/2 )TiO 3 –BaTiO 3 epitaxial thin films on the structure, dielectric, ferroelectric and piezoelectric properties are reported. The thin films were grown by pulsed laser deposition on (La o.5 Sr 0.5 )CoO 3 (LSCO) electrode LaAlO 3 (LAO) substrates using homemade ceramic targets. The (La 0.5 Sr 0.5 )CoO 3 (LSCO)/LaAlO 3 /system was chosen based on the adequate coupling conditions to grow high quality epitaxial films with desired properties. The dielectric and ferroelectric properties are all self-consistent to each other, despite the morphotropic phase boundary effect in Mn doped BNT-BT thin film. Even when remanent polarizations of 17 and 25 μC/cm 2 from BNT-Mn and BNT-BT-Mn thin films were respectively obtained from well-defined P – E hysteresis curves and the corresponding values of coercive field for BNT-Mn and BNT-BT-Mn thin films are 93 and 150 kV/cm, respectively, no significant changes are observed suggesting that the effect of MPB composition is not fully activated due to Mn additions. In the ceramics, the vibrational modes associated to Mn interactions with the oxygen octahedral were identified with Raman spectroscopy. Finally, the local piezoelectric constants ( d 33 ) as measured by PFM are 60 and 124 pm/V for BNT-Mn and BNT-BT-Mn thin films, respectively. Thus, BNT-Mn and BNT-BT-Mn thin films are potential candidates to be used in lead-free piezoelectric devices.

The use of nanotechnology in the piezoelectric industry conveys new concerns about the environmental toxicity related to lead based nanomaterials. Perovskite structured materials are extensively used as piezoelectrics, lead zirconate titanate (PZT) being the primary choice for sensors, actuators, etc., because of its powerful electromechanical conversion. However, during the life cycle of PZT piezoelectrics lead generally leaches into the environment over time, leading to human exposure and potential environmental hazard. Lead-free bismuth based-ferroelectric materials (BNT-BT) are promising substitutes due to their ability to provide all the piezoelectric attributes without leaching toxic material. Yet, little is known about the potential toxicity and interactions of these nanomaterials with biomolecules and their subsequent intracellular localization at the nanoscale. The aim of this study was to compare the biological impact and uptake of lead and bismuth-based piezoelectric nanoparticles in order to present a suitable substitute for the piezoelectric industry. Our results show that BNT-BT and PZT nanoparticles were internalized through the endolysosomal pathway following first order kinetics, nanoparticles were localized in the lamellar bodies without inducing cell toxicity measured by mitochondrial activity and cell membrane integrity. Furthermore, BNT-BT nanoparticles were more stable as lead-based PZT released 20% more lead ions into cell culture media. Finally, we propose bismuth-based BNT-BT as a suitable candidate for commercial use as they avoid environmental leaching, imposing less risk during manufacturing and in occupational health, beside having high biocompatibility and similar physico-chemical properties.

Measurement of mechanical properties in cermets is complex since they are formed by several phases. How to quantitatively determine the relationship between the performance and the complex microstructure of this particular group of materials, especially when analyzing the effect of the reinforcement phase, is still one of the top challenging problems yet to be solved. Hardness and elastic modulus of bimodal WC–Co HVOF thermal spray coatings doped with vanadium carbide (VC) additions were studied by performing a statistical analysis of nanoindentation results. A mathematical deconvolution procedure and a Weibull distribution analysis of hardness and elastic modulus results are proposed to identify the individual contribution of each phase to the mechanical properties of different WC–12Co coatings. Both analysis methods allowed to detect a reinforcing effect of vanadium on the hardness and elastic modulus of bimodal VC-doped coatings. The combination of VC additions and a bimodal WC particle size distribution in the WC–Co coatings proved successful in increasing their mechanical properties, as the coatings processed in this work showed better mechanical properties than that reported in the literature for coatings having exclusively a bimodal WC particle size distribution or those only doped with VC additions.

El objetivo del presente trabajo es ofrecer un procedimiento para el cálculo de la geometría racional de un engranaje cilíndrico con dientes rectos que proporcione elevada resistencia a la picadura, tomando como base la norma AGMA 2101-D04 (American Gear Manufacturers Association;, 2016) y considerando un ambiente de operación, diseño y fabricación específicos. El procedimiento permitirá generar una síntesis geométrica racional del engranaje con menor esfuerzo de contacto en los flancos activos de los dientes conjugados. Son presentadas las relaciones que vincula la geometría del engranaje y su resistencia a esfuerzos de contacto utilizadas en el desarrollo de los modelos matemáticos que dieron soporte al procedimiento de cálculo. También, se muestra un diagrama de bloque para la ejecución del algoritmo base que permitió elaborar el procedimiento. Mediante un análisis por modelos de elementos finitos fue realizada una simulación del desempeño de los engranajes cilíndricos de dientes rectos bajo carga que permitió validar el procedimiento de cálculo y determinar las variables que más influyen en la transformación de esfuerzos con respecto a su geometría. Además, en el reporte de investigación es presentado un resumen del fallo por picadura y sus posibles causas. A procedure for calculating the rational geometry of a spur gears with higher resistance to pitting, based on AGMA Standard 2101-D04 (American Gear Manufacturers Association;, 2016) and considering design, manufacturing, and operation, is presented in this research report. This procedure is oriented to obtain a rational geometrical synthesis of the spur gears with less contact stress on the active flanks of matching teeth. The relationships among the spur gear geometry and its resistance to contact stresses used in the mathematical models that supported the calculation procedure are presented. Also, a block diagram is shown for the clarification of the base algorithm used in the calculation procedure. By means of a finite element model (FEM) analysis, a simulation of the performance of spur gears under load was performed. The FEM analysis allowed a validation of the calculation procedure and determining of the variables with more influence in the variation of contact stresses. In addition, a summary of the pitting failure and its possible causes is presented in this research report.

La unión de un plato de material de acero SAE J2340 grado 420XF y de un engrane 5120H a través de la tecnología de soldadura láser, fueron caracterizadas para definir el proceso donde se tiene la causa raíz de porosidad en la unión y poder alcanzar la reducción de porosidad en el proceso. Se analizaron algunos de los parámetros de proceso para estandarizar sus límites de control y cumplir con la especificación de diseño de soldadura. Se observó mediante espectrometría de emisión óptica, que la composición química de ambas piezas cumplía con la composición química esperada. La microestructura cumplió con los porcentajes de bainita y en retención de austenita de acuerdo con los requerimientos del material. Para el estudio de dureza se observó que las piezas cumplían con la especificación de las normas antes y después de ser sometido a los tratamientos de revenido y carburizado. Para la unión de los materiales por soldadura láser, se analizó la condición de penetración de soldadura, identificando porosidad interna y en la superficie. Se observó que las impurezas impregnadas en la superficie del material son consecuencia de la aplicación de un inhibidor de corrosión, el cual se aplica previo a la estación láser. Los residuos de este inhibidor son los causantes de la generación de porosidad, debido a que por su composición química provoca el fenómeno de fragilización por hidrógeno, durante el proceso de soldadura. Finalmente, por medio de la estandarización de parámetros y de limpieza en el proceso de soldadura láser, junto con las mejoras en las herramientas de la estación de limpieza láser se obtuvo la reducción de porosidad en la unión axial de las dos partes. The union of a plate made of steel material SAE J2340 grade 420XF and a gear 5120H through laser welding technology, was subjected to a characterization analysis to find the cause of porosity in the union and to be able to achieve its reduction in the process. Some of the process parameters were analyzed to standardize their control limits and verify the weld design specification. It was observed the chemical composition of the materials, by optical emission spectrometry, the composition had the key elements within specification. Regarding microstructure, it complied with the percentages of bainite and retention of austenite according to the requirements of the material. The hardness standards values were met before and after being subjected to the tempering and carburizing treatments. The weld penetration condition was analyzed in the union of the materials, identifying internal and surface porosity. It was observed that the impurities impregnated on the surface of the material were due to a corrosion inhibitor, which is applied prior to the laser station, these impurities were the cause of the generation of porosity through the phenomenon of hydrogen embrittlement. Through the standardization of parameters and cleaning in the laser welding process, together with the improvements in the tools of the laser cleaning station, a reduction in porosity was obtained in the axial union of the two parts.

El arranque de un proceso de manufactura en la industria aeroespacial enfrenta diversos retos para cumplir los calendarios de producción. El objetivo de este estudio es determinar una solución concepto que, aplicada a la secuencia del ensamble de partes y componentes aeroespaciales permita minimizar el trabajo detenido, cuando se presenten situaciones problemáticas, como por ejemplo; la ausencia de alguna parte a ensamblar, o una herramienta, o la presencia de una anomalía de calidad en el proceso. Llámese a este enfoque de minimización, gestión del flujo de trabajo. Actualmente puede ser más importante cambiar de un modo de resolución de problemas, que es más o menos aleatorio, a un modo de gestión del flujo del trabajo, junto con el problema, de manera sistémica. La aplicación de la Teoría de Solución de Problemas de Invención, TRIZ, específicamente el algoritmo ARIZ-85C, provee un marco de trabajo ideal para generar una solución concepto. La gestión del flujo de trabajo a través de la configuración de la secuencia de ensamble en unidades mínimas de trabajo racional y basada en las competencias del conocimiento minimiza el trabajo detenido. los resultados demuestran un mejoramiento de un cincuenta por ciento en la proporción de trabajo detenido. La solución es completamente aplicable a secuencias de ensamble de componentes estructurales metálicos, donde algunas pocas competencias se aplican de una manera repetida y la variedad de partes a ensamblar es alta. La gestión del flujo de trabajo contribuye a lograr los objetivos de producción. The start of manufacturing process in the aerospace industry faces several challenges to meet production schedules. The objective of this study is to determine a concept solution that, applied to the assembly sequence of parts and aerospace components, allows to minimize the work stopped, when problematic situations arise, such as; the absence of any part to assemble, or a tool, or the presence of a quality anomaly in the process. Call this approach of minimization, workflow management. Currently it may be more important to change from a problem-solving mode, which is more or less random, to a workflow management mode, together with the problem, in a systemic way. The application of the Theory of Solution of Problems of Invention, TRIZ, provides an ideal work framework to generate a solution concept. The management of the work flow through the configuration of the assembly sequence in minimum units of rational work and based on knowledge competences minimizes the work stopped. The solution is completely applicable to assembly sequences of metal structural components, where a few competences are applied in a repeated manner and the variety of parts to assemble is high. Workflow management helps achieve production goals. Philippe Harpin, Asesor en planta.