Open Access
Relationship between microstructure and fracture types in a UNS S32205 duplex stainless steel
(ABM, ABC, ABPol, 2013) Biezma Moraleda, María Victoria; Berlanga Labari, Carlos; Argandoña Salinas, Gorka; Ingeniería Mecánica, Energética y de Materiales; Mekanika, Energetika eta Materialen Ingeniaritza
Duplex stainless steels are susceptible to the formation of sigma phase at high temperature which could potentially be responsible for catastrophic service failure of components. Thermal treatments were applied to duplex stainless steels in order to promote the precipitation of different fractions of sigma phase into a ferrite-austenite microstructure. Quantitative image analysis was employed to characterize the microstructure and Charpy impact tests were used in order to evaluate the mechanical degradation caused by sigma phase presence. The fracture morphology of the Charpy test specimens were thoroughly observed in SEM, looking for a correlation between the microstructure and the fracture types in UNS S32205 duplex stainless steel. The main conclusion is the strong embrittlement effect of sigma phase since it is possible to observe a transition from transgranular fracture to intergranular fracture as increases the percentage of sigma phase. Thus, the mixed modes of fracture are predominant in the present study with high dependence on sigma phase percentages obtained by different thermal treatments.
Open Access
Multifunctional protective PVC-ZnO nanocomposite coatings deposited on aluminum alloys by electrospinning
(MDPI, 2019) Iribarren Zabalegui, Álvaro; Rivero Fuente, Pedro J.; Berlanga Labari, Carlos; Larumbe Abuin, Silvia; Miguel, Adrián; Rodríguez Trías, Rafael; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PRO-UPNA 18 (6107)
This paper reports the use of the electrospinning technique for the synthesis of nanocomposite micro/nanofibers by combining a polymeric precursor with hydrophobic behavior like polyvinyl chloride (PVC) with nanoparticles of a corrosion inhibitor like ZnO. These electrospun fibers were deposited on substrates of the aluminum alloy 6061T6 until forming a coating around 100 m. The effect of varying the different electrospinning deposition parameters (mostly applied voltage and flow-rate) was exhaustively analyzed in order to optimize the coating properties. Several microscopy and analysis techniques have been employed, including optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Water contact angle (WCA) measurements have been carried out in order to corroborate the coating hydrophobicity. Finally, their corrosion behavior has been evaluated by electrochemical tests (Tafel curves and pitting potential measurements), showing a relevant improvement in the resultant corrosion resistance of the coated aluminum alloys.
Open Access
Comparative study of the metallurgical quality of primary and secondary AlSI10MnMg aluminium alloys
(MDPI, 2021) Bakedano, Asier; Niklas, Andrea; Fernández‐Calvo, Ana Isabel; Plata, Gorka; Lozares, Jokin; Berlanga Labari, Carlos; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería
The use of secondary aluminium is increasingly being promoted in the automotive industry for environmental reasons. The purpose of this study was to demonstrate that it is possible to obtain a recycled AlSi10MnMg(Fe) aluminium alloy with equal metallurgical quality to that of a primary AlSi10MnMg alloy when an adequate melt treatment is applied. The melt treatment consisted of deoxidation, degassing and skimming in accordance with the detailed procedure described in this article. The metallurgical qualities of one primary and two secondary alloys were assessed using thermal analysis, the density index test, the macroinclusion test and the microinclusion level test before and after melt treatment. The thermal analysis allowed us to compare the variables of the solidification cooling curve (Al primary temperature and its undercooling; Al‐Si eutectic temperature and its predictive modification rate). The density index test was used to evaluate the hydrogen gas content in the melt. The macroinclusion test was used to evaluate the melt cleanliness, while the microinclusion level test was used to perform the inclusion identification and quantification analyses. This study showed the feasibility of manufacturing structural components using 100% recycled secondary aluminium alloy through V‐ HPDC technology.
Open Access
Mapping the research landscape of bauxite by-products (red mud): an evolutionary perspective from 1995 to 2022
(Elsevier, 2024) Svobodova-Sedlackova, Adela; Calderón, Alejandro; Fernández, A. Inés; Chimenos, Josep Maria; Berlanga Labari, Carlos; Yücel, Onuralp; Barreneche, Camila; Rodríguez Trías, Rafael; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
The global population growth has significantly impacted energy and raw material consumption, unmatched since the Industrial Revolution. Among metals, aluminium ranks second only to steel, with annual production exceeding 69 million tonnes. Due to its high demand, bauxite, the primary ore from which aluminium is extracted, is now classified as a critical material in the EU and the US, given the potential risk of supply shortages for essential applications. Geographical and production challenges surround bauxite, presenting geo-economic and environmental challenges. A critical concern in aluminium production is managing by-products, notably red mud, a bauxite residue, generating over 175 million tonnes annually worldwide. Comprehensive bibliometric research is imperative due to the high amount of bibliographical resources related to this topic, encompassing circular economy, re-valorisation, sustainability, and disposal. This study employs bibliometric methods to assess red mud valorisation, offering insights into research topics, influential authors, and key journals, shedding light on the past, present, and future of red mud research. Such bibliometric analysis not only highlights the current state of the field but also serves as a valuable tool for decision-making, enabling researchers and policymakers to identify trends, gaps, and areas for further exploration, fostering informed and sustainable advancements in the by-products of the aluminium industry.
Open Access
Study of effect of nickel content on tribocorrosion behaviour of nickel-aluminium-bronzes (NABs)
(MDPI, 2023) Berlanga Labari, Carlos; Claver Alba, Adrián; Biezma Moraleda, María Victoria; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
The simultaneous existence of mechanical erosion and electrochemical corrosion is a common scenario for engineering alloys used in marine environments, such as pump impellers and valves. Nickel–aluminium–bronzes (NABs) are widely used alloys in these environments due to their combination of high corrosion resistance and effective mechanical properties. However, NAB alloys are increasingly cast with reduced nickel content due to its high price and low availability. In this study, we examined the tribocorrosion behaviour of two nickel–aluminium bronzes (C95500 and C95400) with different nickel contents (4.8% and 1.0%, respectively) by means of a pin-on-disk device combined with in situ electrochemistry under 1 M NaCl solution. We conducted tests for pure wear in distilled water, pure corrosion using in situ electrochemistry under 1 M NaCl solution, and a combination of wear and corrosion, called tribocorrosion, to understand the overall synergism that exists between the two. We analysed our results using gravimetric as well as volumetric analysis; in addition, we defined the friction coefficient to compare the effect of open-circuit potential (OCP). We also applied the Tafel method and compared corrosion rates for the different scenarios. We employed confocal microscopy to delimitate the impact of the surface topography of pure wear and its synergistic effect with corrosion, and used an optical microscope to study the materials’ microstructures as cast conditions. We also utilised XRD in the Bragg–Brentano configuration to determine the chemical composition of corrosion products. From the experiments conducted, we concluded that an important synergistic effect existed between the wear and corrosion of both NABs, which was associated with corrosion-induced wear. We found NAB C95400 to be more susceptible to erosion under both conditions compared with NAB C95500 due to the chemical composition and lubricant effect of corrosion products formed during the tribocorrosion tests, which were supported by the enriched Ni corrosion products, particularly the presence of nickel-rich copper chloride, 3Cu3(CuNi)(OH)6CuCl2, in the C95500 alloy. We concluded that, because it increased the nickel content, the NAB alloy offered better wear and corrosion behaviour in sea water conditions due to its protective film nature.
Open Access
Corrosion of cast aluminum alloys: a review
(MDPI, 2020-10-16) Berlanga Labari, Carlos; Biezma Moraleda, María Victoria; Rivero Fuente, Pedro J.; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
Research on corrosion resistance of cast aluminum alloys is reviewed in this article. The effect of the main microstructural features of cast aluminum alloys such as secondary dendrite arm spacing (SDAS), eutectic silicon morphology, grain size, macrosegregation, microsegregation, and intermetallic compounds is discussed. Moreover, the corrosion resistance of cast aluminum alloys obtained by modern manufacturing processes such as semi-solid and additive manufacturing are analyzed. Finally, the protective effects provided by different coatings on the aluminum cast alloys—such as anodized, plasma electrolytic oxidation (PEO), and laser—is reviewed. Some conclusions and future guidelines for future works are proposed.
Open Access
Effect of the temperature in the mechanical properties of austenite, ferrite and sigma phases of duplex stainless steels using hardness, microhardness and nanoindentation techniques
(MDPI, 2017) Argandoña Salinas, Gorka; Berlanga Labari, Carlos; Biezma Moraleda, María Victoria; Rivero Fuente, Pedro J.; Peña, Julio; Rodríguez Trías, Rafael; Mekanika, Energetika eta Materialen Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería Mecánica, Energética y de Materiales
The aim of this work is to study the hardness of the ferrite, austenite and sigma phases of a UNS S32760 superduplex stainless steel submitted to different thermal treatments, thus leading to different percentages of the mentioned phases. A comparative study has been performed in order to evaluate the resulting mechanical properties of these phases by using hardness, microhardness and nanoindentation techniques. In addition, optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been also used to identify their presence and distribution. Finally, the experimental results have shown that the resulting hardness values were increased as a function of a longer heat treatment duration which it is associated to the formation of a higher percentage of the sigma phase. However, nanoindentation hardness measurements of this sigma phase showed lower values than expected, being a combination of two main factors, namely the complexity of the sigma phase structure as well as the surface finish (roughness).
Open Access
A comprehensive review of fatigue strength in pure copper metals (DHP, OF, ETP)
(MDPI, 2024) Jiménez Ruiz, Eduardo; Lostado Lorza, Rubén; Berlanga Labari, Carlos; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
Due to their exceptional electrical and thermal conductivity properties, high-purity copper (Cu-DHP) and copper alloys of similar composition, such as electrolytic tough-pitch (ETP), oxygen-free electronic (OFE) and oxygen-free (OF), have often been used in the manufacture of essential components for the electrical, electronic and power generation industries. Since these components are subject to cyclic loads in service, they can suffer progressive structural damage that causes failure due to fatigue. The purpose of this review is to examine the most relevant aspects of mechanical fatigue in Cu-DHP, ETP, OFE and OF. The impact of many factors on fatigue strength (Se), including the frequency, temperature, chemical environment, grain size, metallurgical condition and load type, were analyzed and discussed. Stress–life (S-N) curves under zero mean stress (σm = 0) were found for high-cycle fatigue (HCF). For non-zero mean stress (σm ≠ 0), stress curves were based on a combination of Gerber, Soderberg and ASME elliptic failure criteria. Stress–life (S-N) curves were also developed to correlate fatigue strength (Se) with stress amplitude (σa), yield strength (Syp) and ultimate strength (Sut). Finally, for low-cycle fatigue (LCF), strain–life (ε-N) curves that establish a relationship between the number of cycles to failure (N) and total strain amplitude (εplastic) were determined. Hence, this review, as well as the proposed curves, provide valuable information to understand fatigue failure for these types of materials.
Open Access
Using the multi-response method with desirability functions to optimize the zinc electroplating of steel screws
(MDPI, 2018) Lostado Lorza, Rubén; Martínez Calvo, María Ángeles; Berlanga Labari, Carlos; Rivero Fuente, Pedro J.; Institute for Advanced Materials and Mathematics - INAMAT2
Zinc electroplating is a coating process controlled by several input process parameters. However, the commonly used input parameters for setting the process of zinc deposition are current density, temperature of the coating solution, zinc concentration, deposition time, and concentration of additives (conditioner and brightener). The power consumed in the zinc plating process, coating thickness, increase in coating mass, and corrosion resistance are considered to be outputs or zinc coating parameters. They are widely used when the zinc coating requirements are based on the coating process cost, coating process speed, corrosion resistance, and coating thickness. This paper seeks to determine regression models by the response surface method (RSM) that relate the zinc coating parameters to the input parameters in steel screws. When considering the coating requirements of cost, coating process speed, corrosion resistance, and coating thickness, the optimal input parameters were found by using a multi-response surface (MRS). Input parameters of 0.3 amps/dm(2), 20.0 degrees C, 13.9 g/L, 45 min, 28.5 mL/L, and 2.8 mL/L, respectively (relative to the commonly used input parameters detailed above), were obtained when considering the cost. Considering minimization of the deposition time, the input parameters obtained were 0.5 amps/dm(2), 24.6 degrees C, 13.9 g/L, 45 min, 26.9 mL/L, and 1.1 mL/L, respectively. The optimal inputs to maximize the corrosion resistance were 0.6 amps/dm(2), 32.4 degrees C, 14.0 g/L, 45 min, 28.7 mL/L, and 2.5 mL/L, respectively. Finally, when maximizing the coating thickness, the inputs were 0.7 amps/dm(2), 38.4 degrees C, 12.2 g/L, 45 min, 26.5 mL/L, and 1.5 mL/L, respectively.
Open Access
Valorisation of red mud: disclosing the potential of an abundant residue
(MDPI, 2025-02-21) Vielma, Carlos A.; Svobodova-Sedlackova, Adela; Chimenos, Josep Maria; Fernández, A. Inés; Berlanga Labari, Carlos; Rodríguez Trías, Rafael; Barreneche, Camila; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Gobierno de Navarra / Nafarroako Gobernua
Red mud (RM), the primary waste product of the aluminium industry, is notable for its high concentrations of metals and rare earth elements (REE). Efforts have been made to develop extraction methods for REE recovery from RM, aiming to enhance its valorisation and reduce the European reliance on external REE sources—particularly crucial for technological advancements and the transition to renewable energy. However, these methods have only been limited to low technology readiness levels (TRLs), with no economically or technically viable processing routes yet defined to enable large-scale industrialisation within a circular economy model. This study characterised RM samples from the Seydişehir region in Türkiye using different techniques and explored the experimental process for recovering metals and REE. Moreover, the study assessed the global prospective potential of RM based on technical and economic data, as well as the sustainability of the implemented process through the life cycle assessment (LCA) tool. Results showed a total REE concentration of up to 1600 ppm, with Ce, being the most abundant (426 ± 27 ppm), followed by La, Nd, and Sc. Concentration efficiencies for La and Nd ranged between 240–300%. Sc, Y, Ce, La, and Nd have significant usage in European markets and represent prime RM targets for further prospecting. The LCA revealed that the highest global warming potential of the sequential extraction process was attributed to hydroxylamine hydrochloride and hydrogen peroxide. The findings highlight the need to explore alternative, more eco-friendly reagents to improve RM valorisation.