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–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.

RESUMENEntender el comportamiento de las oscilaciones de los chorros al interior del molde de planchón delgado tipo embudo es esencial para asegurar una entrega de acero líquido constante, mejorar el control de los patrones de flujo y consecuentemente incrementar la productividad de la planta y la calidad del producto final. Para lograr esto se llevó a cabo un estudio del efecto del diseño interno de la buza sobre la fluido dinámica del molde, intentando determinar el origen de las oscilaciones de los chorros. Se hizo uso de la simulación matemática para estudiar éstos fenómenos.En la modelación matemática, se recurrió a las ecuaciones fundamentales, el modelo de turbulencia RSM y el modelo Multifásico VOF. Las ecuaciones gobernantes son discretizadas y resueltas mediante el método iterativo-segregado implícito implementado en FLUENT®.Los resultados, de la simulación matemática, muestran que aun para diseños de buza con un comportamiento operacional estable, las oscilaciones de los chorros permanecen presentes y se hacen más intensos para altas velocidades de colada e inmersiones de buza profundas. El análisis de cada una de las buzas simuladas muestra que la geometría interna origina perturbaciones en el flujo en las zonas donde las áreas transversales internas cambian, generando presiones dinámicas altas y bajas promoviendo una tendencia para que el acero líquido salga preferentemente por uno de los puertos. Se encontró un delicado balance de fuerzas, el cual, se da sobre sobre la punta de la bifurcación interna de la buza. Este balance está relacionado con las velocidades fluctuantes y la presión ferrostática. Si este balance es roto las oscilaciones son más intensas, originando variaciones permanentes de la velocidad de flujo másico de un puerto a otro. Además, se encontró que existe la formación continua de un camino de vórtices el cual se genera a partir de la separación de la capa límite en el divisor de los puertos, fenómeno que intensifica la oscilación periódica de los chorros.Palabras clave: Diseño de buza; simulación matemática; molde de planchón delgado tipo embudo; oscilación de los chorros; turbulencia. ABSTRACTUnderstanding the behavior of the oscillations of the jets into the mold of thin slab funnel is essential to ensure a constant supply of liquid steel, improve control of the flow patterns and consequently increase plant productivity and the final product quality. To achieve this, we conducted a study of the effect of the internal design of the nozzle on the fluid dynamics of the mold, trying to determine the origin of the oscillations of the jets. Use of mathematical and physical simulation was done to study these phenomena.For the mathematical modeling it resorts to the fundamental equations, the RSM turbulence model and VOF multiphase model. The governing equations are discretized and solved by iteration-segregated implicit method implemented in FLUENT®.The results of the mathematical simulation are showing that even for a nozzle designs with a stable operational performance, the oscillat...

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.

This is an Accepted Manuscript for the Microscopy and Microanalysis 2020 Proceedings. This version may be subject to change during the production process.

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