Publication: Recubrimientos orgánicos en polvo funcionalizados con nanosílice
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2020-12
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2020-12-11
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Abstract
La corrosión es uno de los problemas que más ha preocupado y transcendido durante los últimos años en el ámbito industrial y científico. Con el propósito de evitar la corrosión de los metales, la protección de estos mediante recubrimientos orgánicos o pinturas es una de las medidas más empleadas, debido a su sencillez y bajo coste respecto a otros métodos posibles. Actualmente, una de las estrategias más innovadoras en este campo es la funcionalización de los recubrimientos mediante la nanoadición de diferentes compuestos para hacerlos más resistentes a los agentes externos. De este modo, se pretende aumentar su vida en servicio y reducir así el coste material y económico que supone la corrosión. Además, en los últimos años, cabe destacar que, dentro de los distintos recubrimientos orgánicos existentes, se ha extendido el uso y el estudio de los recubrimientos en polvo debido a las grandes ventajas que presentan estos sobre los recubrimientos líquidos convencionales, como es su mayor compromiso con el medioambiente, ya que no contienen elementos volátiles en su composición.
Por todo lo expuesto anteriormente, en la presente Tesis Doctoral se han fabricado diferentes recubrimientos en polvo funcionalizados con nanopartículas de SiO2 partiendo de materiales comerciales, con el objetivo de mejorar sus propiedades. Se han estudiado tres tipos de recubrimientos en polvo diferentes: epoxi y poliéster (termoestables) y poliamida (termoplástica). Además, en algunas ocasiones, se han estudiado dos tipos de partículas de nanosílice distintas (hidrofílicas e hidrofóbicas), con el propósito de conseguir las mejores prestaciones posibles.
Además, con la finalidad de obtener recubrimientos homogéneos, se han empleado estrategias de mezcla económicas y con el menor consumo energético posible para cada tipo de mezcla: molienda de bolas, mezcladora en caliente o extrusión. La cantidad de nanopartículas de sílice empleada ha sido optimizada para cada material y para cada método de mezcla utilizado.
Se han caracterizado tanto los polvos de pintura una vez mezclados con las nanoadiciones, como los recubrimientos una vez aplicados. La caracterización del polvo de pintura se realizó para conocer la viabilidad del proceso de mezcla, así como la homogeneidad de la distribución de las nanopartículas en los polvos. También se llevaron a cabo estudios cinéticos de curado en los recubrimientos en polvo termoestables para conocer el efecto de las nanopartículas.
Como resultados más relevantes de la presente investigación, se puede concluir que se consiguen mejorar las propiedades mecánicas y la resistencia a desgaste de los tres recubrimientos orgánicos en polvo escogidos con pequeñas cantidades de nanosílice, gracias también, a la buena homogeneidad que se consigue con los diferentes métodos de mezcla empleados. También han mejorado las propiedades mecánicas y de desgaste de algunos recubrimientos tras la exposición a una fuente ultravioleta y, en algún caso se ha comprobado, además, que se mejora la resistencia a corrosión gracias a las nanopartículas de sílice.
Corrosion is one of the problems that has most concerned and transcended in recent years in the industrial and scientific areas. In order to prevent the corrosion of metals, protection with organic coatings is one of the most widely used solutions, because of its simplicity and low cost compared to other possible methods. Currently, one of the most innovative strategies in this field is the functionalization of organic coatings through the nanoaddition of different compounds to make them more resistant to external agents. Thus, this research intends to increase the service life of the organic coatings and reduce the material and economic cost of corrosion. In addition, in recent years, the use and the study of organic powder coatings have increased among the different types of organic coatings, due to their great advantages over conventional liquid coatings, such as their greater environmental friendly character, since they do not contain volatile organic compounds. Therefore, in this Doctoral Thesis, different functionalized powder organic coatings with SiO2 nanoparticles have been manufactured from commercial materials, with the aim of improving their properties. Three different types of powder coatings have been studied: epoxy and polyester (thermosets) and polyamide (thermoplastic). In addition, sometimes, two different types of nanosilica particles (hydrophilic and hydrophobic) have been studied with the aim of achieving the best possible performance. Moreover, in order to obtain homogeneous coatings, economical mixing strategies have been used with the lowest possible energy consumption for each specific mixture: ball milling, hot mixer or extrusion. The amount of silica nanoparticles employed has been optimized for each material and for each mixing method. Both the organic powders mixed with the nanoadditions, and the applied coatings, have been characterized. The characterization of the powders has been carried out to know the feasibility of the mixing process, as well as the homogeneity of the distribution of the nanoparticles in the powders. Curing kinetic studies have also been carried out for thermoset powder coatings to study the effect of nanoparticles. Regarding the characterization of the organic coatings after being applied on the metallic substrates, most of the tests carried out have focused on the study of the mechanical behavior and wear resistance of the three functionalized coatings. In addition, other relevant studies have been performed for the final coatings, such as thermal analysis, wettability measurements, evaluation of aesthetic properties, and studies of the morphology and homogeneity of the nanoreinforced coatings. Finally, other types of additional studies have also been carried out for the coatings with the better performance, such as the analysis of weathering resistance after exposing coatings to an ultraviolet source and electrochemical measurements to know the behavior against corrosion. As the most relevant results of this research, it can be concluded that the mechanical properties and wear resistance of the three chosen organic powder coatings can be improved with small amounts of nanosilica, thanks to the good homogeneity that is achieved with the different mixing methods used. Mechanical and wear properties of some coatings have also been increased after exposure to an ultraviolet source and, in some cases, an improvement on corrosion resistance due to silica nanoparticles additions has been checked.
Corrosion is one of the problems that has most concerned and transcended in recent years in the industrial and scientific areas. In order to prevent the corrosion of metals, protection with organic coatings is one of the most widely used solutions, because of its simplicity and low cost compared to other possible methods. Currently, one of the most innovative strategies in this field is the functionalization of organic coatings through the nanoaddition of different compounds to make them more resistant to external agents. Thus, this research intends to increase the service life of the organic coatings and reduce the material and economic cost of corrosion. In addition, in recent years, the use and the study of organic powder coatings have increased among the different types of organic coatings, due to their great advantages over conventional liquid coatings, such as their greater environmental friendly character, since they do not contain volatile organic compounds. Therefore, in this Doctoral Thesis, different functionalized powder organic coatings with SiO2 nanoparticles have been manufactured from commercial materials, with the aim of improving their properties. Three different types of powder coatings have been studied: epoxy and polyester (thermosets) and polyamide (thermoplastic). In addition, sometimes, two different types of nanosilica particles (hydrophilic and hydrophobic) have been studied with the aim of achieving the best possible performance. Moreover, in order to obtain homogeneous coatings, economical mixing strategies have been used with the lowest possible energy consumption for each specific mixture: ball milling, hot mixer or extrusion. The amount of silica nanoparticles employed has been optimized for each material and for each mixing method. Both the organic powders mixed with the nanoadditions, and the applied coatings, have been characterized. The characterization of the powders has been carried out to know the feasibility of the mixing process, as well as the homogeneity of the distribution of the nanoparticles in the powders. Curing kinetic studies have also been carried out for thermoset powder coatings to study the effect of nanoparticles. Regarding the characterization of the organic coatings after being applied on the metallic substrates, most of the tests carried out have focused on the study of the mechanical behavior and wear resistance of the three functionalized coatings. In addition, other relevant studies have been performed for the final coatings, such as thermal analysis, wettability measurements, evaluation of aesthetic properties, and studies of the morphology and homogeneity of the nanoreinforced coatings. Finally, other types of additional studies have also been carried out for the coatings with the better performance, such as the analysis of weathering resistance after exposing coatings to an ultraviolet source and electrochemical measurements to know the behavior against corrosion. As the most relevant results of this research, it can be concluded that the mechanical properties and wear resistance of the three chosen organic powder coatings can be improved with small amounts of nanosilica, thanks to the good homogeneity that is achieved with the different mixing methods used. Mechanical and wear properties of some coatings have also been increased after exposure to an ultraviolet source and, in some cases, an improvement on corrosion resistance due to silica nanoparticles additions has been checked.
Description
Mención Internacional en el título de doctor
Esta tesis contiene artículos de investigación
Esta tesis contiene artículos de investigación
Keywords
Pulvimetalurgia, Corrosión, Oxidación, Nanopartículas de sílice, Materiales de recubrimiento