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Cold Spray Deposition of WC-Co Cermets
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[spa] En primer lugar, el objetivo principal de este trabajo de investigación fue proporcionar un nuevo método de deposición para depositar cermets de WC-Co. Esta nueva tecnología proporcionó nuevos recubrimientos sin ninguna descomposición de la microestructura del polvo inicial y por lo tanto la mejora de las presentes aplicaciones de WC-Co en la gran industria. La deposición de cermets de WC-Co resistentes al desgaste ha sido siempre una de las principales aplicaciones de las técnicas de proyección térmica convencionales como por ejemplo High Velocity Oxy-Fuel (HVOF). Las demandas de la industria en términos de producción y la necesidad y constante búsqueda de mejores propiedades mecánicas y electroquímicas conducen al objetivo principal y la motivación de esta tesis: la producción de nuevos y mejores recubrimientos de WC-Co sobre varios sustratos utilizando una técnica de deposición nueva, Cold Gas Spraying (CGS). El hecho de que antes de la publicación del primer artículo que nació de este trabajo de investigación no se había depositado previamente con éxito este tipo de materiales por CGS fue también uno de los principales puntos de motivación. Por esta razón, el lector encontrará, en la integridad del documento, los trabajos de investigación que fueron publicados durante estos años de programa de doctorado y cumplen los objetivos principales de esta tesis titulada "Deposición de cermets de WC-Co por Proyección Fría"
[eng] The main subject of this Thesis is the production of hard, wear and corrosion resistant cermets tungsten carbide and cobalt cermets (WC-Co) with different contents in cobalt matrix, onto low carbon steels and aluminum alloy Al7075-T6 substrates, by means of Cold Gas Spray (CGS). The current state of the art for the deposition of WC-Co uses High Velocity Oxy-Fuel (HVOF) as the main technique. Understanding both techniques was also one of the keys points in this work. A deep theoretical approach about the CGS process, in which no melting of the particles occurs, was made at first to gain a better comprehension about the behaviour of the powder particles when sprayed onto different substrates and therefore being able to produce good quality coatings. The starting purpose of this doctoral Thesis was to produce WC-25, 17 and 12%Co coatings onto low carbon steel and Al7075-T6 substrates. Until the day, using nitrogen as the process gas, such coatings could not be produced with enough adhesion, thickness and wear and corrosion properties. These are the main characteristics sought by the industry in these coatings. In the end of this doctorate WC-Co coatings were obtained with excellent mechanical and electrochemical properties, adhesion to both low carbon steel and Al7075-T6 substrates. Besides, these properties were increased and improved when compared to the same WC-Co coatings obtained by HVOF conventional deposition technique. Initial problems such as flowability of the powders, bad adherence to the substrate, poor coating quality and extremely low deposition efficiencies were resolved during the period of the Thesis. Also, and taking advantage of the novel coatings and excellent properties obtained using the referred feedstock powders and substrates, the knowledge was transferred to the industry as a trade secret.
[eng] The main subject of this Thesis is the production of hard, wear and corrosion resistant cermets tungsten carbide and cobalt cermets (WC-Co) with different contents in cobalt matrix, onto low carbon steels and aluminum alloy Al7075-T6 substrates, by means of Cold Gas Spray (CGS). The current state of the art for the deposition of WC-Co uses High Velocity Oxy-Fuel (HVOF) as the main technique. Understanding both techniques was also one of the keys points in this work. A deep theoretical approach about the CGS process, in which no melting of the particles occurs, was made at first to gain a better comprehension about the behaviour of the powder particles when sprayed onto different substrates and therefore being able to produce good quality coatings. The starting purpose of this doctoral Thesis was to produce WC-25, 17 and 12%Co coatings onto low carbon steel and Al7075-T6 substrates. Until the day, using nitrogen as the process gas, such coatings could not be produced with enough adhesion, thickness and wear and corrosion properties. These are the main characteristics sought by the industry in these coatings. In the end of this doctorate WC-Co coatings were obtained with excellent mechanical and electrochemical properties, adhesion to both low carbon steel and Al7075-T6 substrates. Besides, these properties were increased and improved when compared to the same WC-Co coatings obtained by HVOF conventional deposition technique. Initial problems such as flowability of the powders, bad adherence to the substrate, poor coating quality and extremely low deposition efficiencies were resolved during the period of the Thesis. Also, and taking advantage of the novel coatings and excellent properties obtained using the referred feedstock powders and substrates, the knowledge was transferred to the industry as a trade secret.
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PEREIRA DE MAGALHAES E COUTO, Miguel. Cold Spray Deposition of WC-Co Cermets. [consulta: 24 de gener de 2026]. [Disponible a: https://hdl.handle.net/2445/61858]