Person: Arrabal Durán, Raúl
Universidad Complutense de Madrid
Faculty / Institute
Ingeniería Química y de Materiales
Ciencia de los Materiales e Ingeniería Metalúrgica
Now showing 1 - 10 of 11
PublicationDesign and Multidimensional Screening of Flash-PEO Coatings for Mg in Comparison to Commercial Chromium(VI) Conversion Coating(MDPI, 2021-02-17) Wierzbicka, Ewa; Mohedano Sánchez, Marta; Matykina, Endzhe; Arrabal Durán, RaúlREACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulations demand for an expedient discovery of a Cr(VI)-free alternative corrosion protection for light alloys even though the green alternatives might never be as cheap as current harmful technologies. In the present work, flash- plasma electrolytic oxidation coatings (FPEO) with the process duration < 90 s are developed on AZ31B alloy in varied mixtures of silicate-, phosphate-, aluminate-, and fluoride-based alkaline electrolytes implementing current density and voltage limits. The overall evaluation of the coatings’ anticorrosion performance (electrochemical impedance spectroscopy (EIS), neutral salt spray test (NSST), paintability) shows that from nine optimized FPEO recipes, two (based on phosphate, fluoride, and aluminate or silicate mixtures) are found to be an adequate substitute for commercially used Cr(VI)-based conversion coating (CCC). The FPEO coatings with the best corrosion resistance consume a very low amount of energy (~1 kW h m−2 µm−1). It is also found that the lower the energy consumption of the FPEO process, the better the corrosion resistance of the resultant coating. The superb corrosion protection and a solid environmentally friendly outlook of PEO-based corrosion protection technology may facilitate the economic justification for industrial end-users of the current-consuming process as a replacement of the electroless CCC process. PublicationFlash-PEO coatings loaded with corrosion inhibitors on AA2024(Elsevier, 2020-08-20) Olmo Martínez, Rubén del; Mohedano Sánchez, Marta; Visser, Peter; Matykina, Endzhe; Arrabal Durán, RaúlFlash plasma electrolytic oxidation (flash-PEO) with in situ incorporation of inhibitors is explored as a strategy for corrosion protection of 2024 aluminium (Al) alloys. Thin (~5 μm) and energy-efficient coatings were successfully developed on the Al substrate in 100 s treatment time using different electrolytes based on molybdate, stannate, tungstate, vanadate lanthanum or cerium salts additives with and without complexing agent (EDTA). Screening of the optimum combination in search of minimum thickness and best corrosion protective performance was performed using electrochemical impedance spectroscopy (EIS). Coatings based on EDTA-Ce and WO42 were selected and investigated further in comparison with the inhibitor-free phosphate coating in terms of morphology, composition, corrosion behaviour and paint adhesion. EDTA-Ce coating showed excellent paint adhesion and the highest impedance modulus at short immersion times in 3.5 wt% NaCl aqueous solution. Neutral salt spray testing of this coating as a full system comprising an epoxy primer showed no signs of corrosion after 1000 h of exposure. PublicationHybrid sol-gel coatings applied on anodized AA2024-T3 for active corrosion protection(Elsevier Science, 2021-08-15) Olmo Martínez, Rubén del; Tiringer, U.; Milosev, I; Visser, P.; Arrabal Durán, Raúl; Matykina, EndzheThe effect of the presence of an anodic film and hybrid sol-gel coating loaded with corrosion inhibitors was evaluated as a strategy for enhanced barrier and active corrosion protection of aluminium alloy 2024-T3. In this study, AA2024-T3 specimens were anodized in a modified sulphuric-citric acid bath (SCA) as the first layer of a corrosion protective multilayer system and subsequently protected by the application of silica-based hybrid sol-gel coatings. These coatings were doped with LiNO3 and Ce(NO3)3 as corrosion inhibitors and studied in comparison with the inhibitor-free sol-gel coating in terms of morphology, composition and corrosion protection of intact and scribed specimens. The anodized AA2024-T3 with an overlaying inhibitor-free sol-gel coating showed the highest impedance modulus during long-term immersion in 0.1 mol·L−1 NaCl aqueous solution. Active corrosion protection of scribed coated specimens was studied by exposure to a 0.5 mol·L−1 NaCl solution and evaluated by surface analytical techniques. The addition of Li- and Ce-based salts into the hybrid sol-gel formulation showed active corrosion protection compared to the inhibitor-free scribed hybrid sol-gel coating. The Ce-doped sol-gel coating showed less visual corrosion and higher active corrosion protection than the Li-containing one during the long-term immersion test in 0.5 mol·L−1 NaCl. Present findings reveal that the combination of the anodic/hybrid sol-gel layers on AA2024-T3 enhances the corrosion protective properties barrier properties of both stand-alone systems and the incorporation of Li- and Ce-based inhibitors provide active corrosion. PublicationPLA deposition on surface treated magnesium alloy: Adhesion, toughness and corrosion behaviour(Elsevier Science, 2020-04-25) Muñoz, Marta; Torres, Belén; Mohedano Sánchez, Marta; Matykina, Endzhe; Arrabal Durán, Raúl; López, A.J.; Rams, J.This study shows that the use of polylactic acid polymer (PLA) coatings deposited by dip-coating on AZ31 magnesium alloy can increase the integrity of the system and the fracture toughness of magnesium substrates treated by plasma electrolytic oxidation (PEO). This provides a novel and promising use of a multilayered system made of fully biocompatible materials. The maximum adhesion strength value for PLA coatings on AZ31 was >50% higher than the maximum one for AZ31/PEO/PLA, while the maximum bending strain tripled. The limitations observed in the AZ31/PEO system arise from the brittle nature of the oxides formed during PEO treatments; their negative impact is reduced when incorporating a PLA layer that is capable of filling the pores and sealing the cracks of the PEO layer. PLA coatings reduce corrosion of AZ31 and maintain the corrosion protection provided by the PEO treatments. The characteristics of the PLA coatings on AZ31 Mg alloy and on AZ31/PEO systems were evaluated by using a Taguchi design of experiment (DOE) method using the following processing parameters: (i) number of layers, (ii) withdrawal speed and (iii) polymer concentration. The effect of these three degrees of freedom and, the surface treatment has been evaluated with regards to different properties desired for the coatings, i.e., adhesion, thickness, roughness, and corrosion resistance. PublicationBiotribology and biocorrosion of MWCNTs-reinforced PEO coating on AZ31B Mg alloy(Elsevier Science, 2021-03-05) Daavari, Morteza; Atapour, Masoud; Mohedano Sánchez, Marta; Arrabal Durán, Raúl; Matykina, Endzhe; Taherizadeh, AboozarOver the last two decades, various methods have been developed for surface modification of Mg alloys among which plasma electrolytic oxidation (PEO) is one of the most effective methods for tailoring surface properties. However, PEO coatings still need to be improved in various aspects, including mechanical and corrosion performances. In the current study, multi-walled carbon nanotubes (MWCNTs) were incorporated into a PEO coating structure via one-step process. Characterization techniques in this study included scanning electron microscopy (SEM), Raman spectroscopy and X-ray diffraction (XRD). Corrosion behavior was evaluated by electrochemical tests taking into account quasi-in vivo conditions in order to get closer to implant degradation rates in human body. Dry-wear and tribocorrosion in SBF were also evaluated in reciprocal ball-on-plate mode. According to the findings, MWCNTs induced several microstructural modifications in PEO coating such as formation of ~ 1 μm homogeneous dense barrier layer and irregular-shape porosities. Reinforcement significantly improved pitting corrosion resistance of the PEO coating, yielded a low friction coefficient and decreased wear-related damage by 60%. PublicationCa-based sealing of plasma electrolytic oxidation coatings on AZ91 Mg alloy(Elsevier, 2021-04-22) Lu, Xiaopeng; Ma, Jirui; Mohedano Sánchez, Marta; Pillado Rios, Borja; Arrabal Durán, Raúl; Qian, Kun; Li, Yan; Zhang, Tao; Wang, FuhuiPlasma electrolytic oxidation (PEO) coatings on AZ91 Mg alloy were sealed in calcium nitrate solutions at different pH values (3, 4 and 5). Sodium dodecyl sulfate (SDS) was added to study the effect of SDS on the corrosion resistance of the sealed coatings. The microstructure, chemical composition and corrosion resistance of the coatings were investigated by means of SEM, XPS, XRD and electrochemical corrosion tests. The corrosion performance of the coatings was improved due to precipitation of Ca-containing precipitate. Low pH and SDS addition enhanced hydroxyapatite precipitation and produced hydrophobic coatings with worse paint adhesion but better corrosion resistance. PublicationFlash-PEO as an alternative to chromate conversion coatings for corrosion protection of Mg alloy(Elsevier Science, 2020-11-14) Wierzbicka, Ewa; Vaghefinazari, B.; Lamaka, S.V.; Zheludkevich, Mikhail; Mohedano Sánchez, Marta; Moreno Turiegano, Lara; Visser, P.; Rodríguez, Alicia; Velasco, Jorge; Arrabal Durán, Raúl; Matykina, EndzheIn the present work, a flash-PEO coating is developed on AZ31B alloy in a combination of silicate, phosphate, and fluoride based electrolyte in order to offer a green alternative to chromate conversion coatings. Multilevel active protection is achieved through synergetic combination of self-sealing effect of PEO coating itself and active inhibition provided by an organic inhibitor impregnated in PEO pores in a post-treatment step. The results indicate that flash-PEO coatings, loaded with organic corrosion inhibitors, can be recommended for exploitation on industrial level as an equally effective corrosion protection system alternative to CCC for paint-bearing and paint-free applications. PublicationEffects of pre-anodizing and phosphates on energy consumption and corrosion performance of PEO coatings on AA6082(Elsevier, 2021-01-22) Mohedano Sánchez, Marta; Mingo, Beatriz; Mora Sánchez, Hugo; Matykina, Endzhe; Arrabal Durán, RaúlA significant reduction in the energy consumption of Plasma Electrolytic Oxidation (PEO) coatings on AA6082 alloy was obtained using strategies based on electrolyte selection and a precursor anodic film. PEO coatings were developed on AA6082 in silicate-based electrolytes with different phosphate species without and with a precursor oxide layer. The electrical response and, therefore, the specific energy consumption depended on the phosphate species and most notably on the applied pretreatment. The best result was obtained after anodic pretreatment and PEO in silicate-polyphosphate electrolyte with a reduction up to ⁓66% in comparison with the most conventional treatment (direct PEO in orthophosphate electrolyte). The corrosion response is not affected significantly by the pre-anodizing treatment either for short or prolonged immersion times revealing that coatings synthesised under high-energy efficient conditions have comparable corrosion performance under aggressive corrosive environments compared to conventional PEO processes. PublicationHybrid functionalized coatings on Metallic Biomaterials for Tissue Engineering(Elsevier, 2021-07-17) Santos Coquillat, Ana María; Martínez Campos, Enrique; Mora Sánchez, Hugo; Moreno Turiegano, Lara; Arrabal Durán, Raúl; Mohedano Sánchez, Marta; Gallardo, Alberto; Rodríguez Hernández, Juan; Matykina, EndzheThe review encompasses state-of-the-art strategies for design and fabrication of smart biomaterials for tissue engineering. The focus of the work is mainly put on metallic biomaterials with hybrid coatings consisting of bioceramic and polymeric layers with hierarchical organization and drug-eluting capacity. Key technologies and steps to design hybrid smart and multifunctional coatings on metallic cores for bone regeneration implants and cardiovascular stents are outlined, including additive manufacturing of titanium and magnesium alloys for permanent and temporary implant applications. Three levels of hierarchical surface functionalization are described: i) in situ modification of the core material, incorporating bioactive inorganic species and phases by means of ceramic coatings via anodic electrochemical treatments; ii) post-treatment application of polymer layers, monolithic or with specific porous breath figure topography; and iii) application of a cellular therapy component (single cell or cell sheet). Recent progress in incorporation of drug-eluting functionality into such materials via direct or nanocarrier-assisted loading is also highlighted. PublicationPermanganate loaded Ca-Al-LDH coating for active corrosion protection of 2024-T3 alloy(Elsevier, 2022-02-01) Olmo Martínez, Rubén del; Mohedano Sánchez, Marta; Matykina, Endzhe; Arrabal Durán, RaúlCa-Al-Layered Double Hydroxide (Ca-Al-LDH) coating was explored on 2024-T3 aluminium alloy by in situ growth methodology following a 1 h treatment at atmospheric pressure. Mn-based species were successfully incorporated into the Ca-Al-LDH structure by a low-temperature post-treatment (Ca-Al-LDH-Mn). Both LDH coatings disclosed a flaky-like morphology and low thickness (~0.6 µm). Ca-Al-LDH-Mn coating showed optimal paint adhesion and the highest long-term corrosion resistance in 3.5 wt% NaCl solution. Evaluation of scribed LDH specimens by SEM/EDS techniques up to 7 days of immersion in 3.5 wt% NaCl solution revealed that the presence of Mn species in the Ca-Al-LDH-Mn provided active corrosion protection.