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
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
A comprehensive study on hot corrosion resistance of NiCoCrAlYTa and NiCrAl thermal-sprayed coatings for CSP applications
(Elsevier, 2023) Aristu Ojer, Daniel; Berlanga Labari, Carlos; Alberro, Mikel; Rández Diago, Xabier; Fernández, Ángel G.; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
The new generation of concentrated solar power (CSP) plants could be able to work at temperatures up 650 °C and carbonates molten salts are one of the main candidates to be used as thermal energy storage (TES) materials. Molten salt corrosion has been defined as one of the main issues and the technology demands more resistance alloys and innovative coatings. In this study, the assessment of hot corrosion resistance for NiCoCrAlYTa and NiCrAl thermal-sprayed coatings has been undertaken, tested on a ternary eutectic mixture (Li2CO3-Na2CO3-K2CO3) at a temperature of 650 °C. Electrochemical impedance spectroscopy and linear polarization resistance tests were used to evaluate the behaviour of the coatings but the obtained results reveal high values of corrosion rates accompanied by the formation of cracks. This unsatisfactory performance of the coatings, analysed by scanning electron microscopy and x-ray diffraction, can be attributed to a combination of different factors such as porosity, internal material stresses and thermal diffusion phenomena. As a result, it is concluded that further research is necessary to explore new coating application techniques.
Open Access
Corrosion behavior in volcanic soils: in search of candidate materials for thermoelectric devices
(MDPI, 2021-12-21) Berlanga Labari, Carlos; Catalán Ros, Leyre; Palacio, José F.; Pérez Artieda, Miren Gurutze; Astrain Ulibarrena, David; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería; Institute for Advanced Materials and Mathematics - INAMAT2
Thermoelectric generators have emerged as an excellent solution for the energy supply of volcanic monitoring stations due to their compactness and continuous power generation. Nevertheless, in order to become a completely viable solution, it is necessary to ensure that their materials are able to resist in the acidic environment characteristic of volcanoes. Hence, the main objective of this work is to study the resistance to corrosion of six different metallic materials that are candidates for use in the heat exchangers. For this purpose, the metal probes have been buried for one year in the soil of the Teide volcano (Spain) and their corrosion behavior has been evaluated by using different techniques (OM, SEM, and XRD). The results have shown excessive corrosion damage to the copper, brass, and galvanized steel tubes. After evaluating the corrosion behavior and thermoelectric performance, AISI 304 and AISI 316 stainless steels are proposed for use as heat exchangers in thermoelectric devices in volcanic environments.
Open Access
Effect of Ti on microstructure, mechanical properties and corrosion behavior of a nickel-aluminum bronze alloy
(ABM, ABC, ABPol, 2021-04-12) Rivero Fuente, Pedro J.; Berlanga Labari, Carlos; Palacio, José F.; Biezma Moraleda, María Victoria; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
Nickel-aluminum bronze (NAB) alloys are suitable, in cast condition, to be used in marine propellers due to its excellent behavior avoiding erosion and cavitation as well as corrosion. A complex microstructure, intrinsic to this copper base system, is the result of a well-controlled chemical composition. There are few works related to the effect of adding small quantities of specific chemical elements on NAB alloys properties. The aim of this paper is to study the effect of Ti on the microstructure, mechanical properties, and corrosion behavior of a particular NAB alloy, CuAl10Fe5Ni5 (C95500), and the comparison to the Ti-free NAB alloy. Although the as- cast microstructure is very similar for both materials, the addition of only 120 ppm Ti leads to a significant grain refinement that plays a key role on the mechanical properties. It has been observed an increase in both microhardness and nanohardness as well as in the resultant Young moduli values, meanwhile no significant impact on the corrosion susceptibility has been observed.
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
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.