Adrián Claver

This work investigates the synergistic effect of femtosecond laser surface texturing (LST) and AlCrN coating on the wear performance of fine blanking tools. Dimple textures with 10, 15% and 20% surface coverage were fabricated on AISI M2 steel and coated with 1.5 µm AlCrN coating via HIPIMS. SEM and optical confocal microscopy confirmed the high geometrical accuracy of LST features and good coating adhesion at the coating-dimple interface. Contact angle measurements indicated that the as-coated surfaces were oleophilic, while increasing the textured area density led to a progressive shift toward higher contact angles, indicating a modification of lubricant spreading behavior. Ball-on-disk tests were performed under loads of 10, 30 and 50 N trying to simulate fine blanking contact conditions. An initial lubricant supply of 0.05 mL was sufficient to maintain a stable separation film, resulting in friction coefficients between 0.10 and 0.14 regardless of textured area density. In terms of wear, uncoated dimple-textured surfaces did not yield beneficial behaviour, showing higher wear rates than the untextured surface. In contrast, the application of the AlCrN coating on the untextured surface resulted in an approximately 90% reduction in the wear coefficient. A comparable wear reduction was observed for the sample textured at 10% dimple density; however, further increases in texture density led to an exponential increase in wear rate. SEM/EDX observations indicate that debris entrapment within the dimples promote third-body abrasion, contributing to the increased wear at higher texture densities.

Nickel aluminum bronze (NAB) and manganese aluminum bronze (MAB) are widely used in propulsion and seawater handling systems in naval platforms due to their attractive combination of mechanical strength, toughness, and very low susceptibility to marine corrosion. Nevertheless, it is well known that they can suffer from selective phase corrosion and erosion–corrosion, primarily caused by cavitation and sand erosion. Both alloys have a multiphase microstructure that governs their mechanical and chemical behavior. The tribocorrosion behavior of cast NAB and MAB alloys was studied in artificial seawater to analyze the effect on microstructure. The microstructure and nanohardness were evaluated and correlated with tribocorrosion test results conducted under two different loads (10 and 40 N) in a unidirectional sliding mode using a 1 M NaCl solution as the electrolyte. A significant increase in the corrosion rate due to the wear effect was observed in both alloys. MAB exhibited a slightly better tribocorrosion performance than NAB, which was attributed to significant differences in the shape, distribution, and size of the intermetallic kappa phases—rich in iron, aluminum, and nickel—within the microstructure. Pitting corrosion was observed in NAB, while selective corrosion of kappa phases occurred in MAB, highlighting the role of the protective layer in the tribocorrosion behavior of both alloys. These findings were supported by post-test solution analysis using ICP-AES and corrosion product characterization by EDX. A synergistic effect between wear and corrosion was confirmed for both alloys, as erosion removes the protective layer, exposing fresh material to continuous friction and favoring a progressive material loss over time. The practical impact of this study lies in improving the control and design of highly alloyed bronze microstructures under in-service corrosion–erosion conditions.

La mayoría de componentes mecánicos fabricados con acero estructural, están protegidos con una capa de zinc para mejorar su resistencia a la corrosión, en particular atmosférica, y a fenómenos superficiales de desgaste, en particular derivados de la abrasión. Existen diferentes tecnologías para aplicar la capa de zinc sobre el acero, tales como el galvanizado por inmersión, electrodeposición, difusión térmica (sherardizado) y metalización, que producen capas de diferentes composiciones, espesores y propiedades sobre el substrato de acero. En este trabajo, se compara la resistencia al desgaste de probetas de acero al carbono S235JR metalizadas mediante spray térmico con recubrimientos de Zn y de la aleación Zn -Al, con tres espesores diferentes (50, 100 y 200 micras). En un trabajo futuro, se realizará un estudio similar con recubrimientos de galvanizado obtenidos en caliente. De esta forma, se pretende comprobar la influencia de la técnica en la aplicación de recubrimientos de zinc. Los resultados obtenidos durante los ensayos de tribología, realizados mediante pin-on-disc sin lubricante, empleando bola de acero templado de 100Cr6 de 6mm de diámetro, con 10 N de carga, 100 revoluciones por minuto de velocidad de giro; 14 mm de radio de la pista y una duración del ensayo de 1800s, se han analizado a posteriori mediante el empleo de microscopía confocal. Asimismo, se ha determinado la microdureza de ambos recubrimientos respecto al substrato de acero. Todo ello ha permitido concluir el gran efecto que tiene el tipo de técnica de recubrimiento base zinc sobre el acero en su comportamiento tribológico.

Sheet metal forming processes are widely used in applications such as those in the automotive or aerospace industries. Among them, punching is of great interest due to its high productivity and low operating cost. However, it is necessary to optimize these processes and adjust their parameters, such as clearance, shear force or tool geometry, to obtain the best finishes and minimize crack generation. Thus, the main objective of this research work is to optimize the punching process to achieve parts that do not require subsequent processes, such as deburring, by controlling the properties of the starting materials and with the help of tools such as design of experiments and simulations. In the present study, tensile tests were performed on three steels with different compositions and three sample geometries. The information obtained from these tests has allowed us to determine the parameters of the Johnson–Cook damage criteria. Moreover, punching was performed on real parts and compared with simulations to analyze the percentage of burnish surface. The results obtained show that the methodology used was correct and that it can be extrapolated to other types of die-cutting processes by reducing the percentage of surface fractures and predicting the appearance of cracks. Furthermore, it was observed that clearance has a greater influence than processing speed, while the minimum percentage of the burnish area was observed for the minimum values of clearance.

This thesis explores the development of new coating strategies using Physical Vapor Deposition (PVD) techniques and their combination with others such as Plasma Electrolytic Oxidation (PEO) or sol-gel, in order to solve this problem and allow their application in the biomedical industry.

The utilization of diamond-like carbon (DLC) coatings has emerged as a promising strategy to enhance the performance, durability, and functionality of industrial tools and components. Recognized for their exceptional attributes such as hardness, wear resistance, low friction, and biocompatibility, DLC coatings have achieved widespread acclaim for their potential to improve the capabilities of tool steels for different applications. This present study shows a comprehensive investigation into the application of DLC coatings on a diverse range of tool steel substrates, encompassing 1.2379, 1.2358, Caldie, K340, HWS, and Vanadis 4. The main aim is to show the effects of DLC coatings on these substrates and to provide an in-depth analysis of their properties during forming processes. Furthermore, this study explores the practical utilization of DLC-coated tool steel components, with a particular focus on their role in cold forming dies. Additionally, the study reviews the application of duplex treatments involving plasma nitriding to enhance DLC coating performance. To sum up, this study pursues a threefold objective: to investigate DLC coatings’ performance on diverse tool steel substrates; to assess the potential for improvement through nitriding; and to evaluate the behavior of DLC coatings in the cold stamping of S235 steel, which is of great technological and industrial interest to the cold forging sector.

In this work, hydrogenated and hydrogen-free Diamond-Like Carbon (DLC) coatings were deposited into ZK60 magnesium alloy using the promising coating method High-Power Impulse Magnetron Sputtering (HiPIMS). CrC and WC were used as interlayers of the thin films, and their influence was studied. The structure and composition of the coatings were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy. Tribological tests, scratch tests, and nanoindentation were performed to obtain information about the mechanical and tribological properties of the coatings. Finally, immersion and electrochemical tests were performed to evaluate the corrosion behavior of the samples. The results showed a homogeneous layer with improved wear resistance, toughness, and hardness in addition to good adhesion to the substrate of the ZK60 magnesium alloy. The hydrogenated DLC coating showed better results that the hydrogen-free thin layer, and relevant differences were observed depending on the interlayer. In this work, the improvement in the tribological and corrosive properties of Mg alloys was studied by using thin layers of DLC and different intermediate layers, achieving similar or even better wear and adhesion values than with thicker layers.

The objective of this experimental work was to examine and characterise the route for obtaining demonstrative temporary biodegradable personalised implants from the Mg alloy Mg-10Zn-0.5Zr-0.8Ca (wt.%). This studied Mg alloy was obtained in its powder state using the mechanical alloying method, with shape and size characteristics suitable for ensuing 3D additive manufacturing using the SLM (selective laser melting) procedure. The SLM procedure was applied to various processing parameters. All obtained samples were characterised microstructurally (using XRD—X-ray diffraction, and SEM—scanning electron microscopy); mechanically, by applying a compression test; and, finally, from a corrosion resistance viewpoint. Using the optimal test processing parameters, a few demonstrative temporary implants of small dimensions were made via the SLM method. Our conclusion is that mechanical alloying combined with SLM processing has good potential to manage 3D additive manufacturing for personalised temporary biodegradable implants of magnesium alloys. The compression tests show results closer to those of human bones compared to other potential metallic alloys. The applied corrosion test shows result comparable with that of the commercial magnesium alloy ZK60.

The automotive industry has undergone significant advancements and changes over time, resulting in the use of more complex parts in modern vehicles. As a consequence, the parts used in the manufacturing process are subject to higher stress levels, which reduce their service life. To mitigate this issue, surface treatments can be applied to improve the mechanical properties of the tools. In this study, we examined the impact of surface treatments on reducing tool stress during a cold forming process. The process involved reducing the thickness of a sheet from 6 mm to 2.5 mm, which generated high stresses in the tooling. We used finite element stress calculations to analyze the process and found that by reducing the friction coefficient to 0.1, tool stresses can be reduced by 20%, leading to an increase in tool life. Moreover, the press force and tool wear were also reduced by 18%. To validate the theoretical calculations, we performed field tests in a real manufacturing process.