Long-term Corrosion Tests Research Articles

ENHANCING SURFACE CHARACTERISTICS OF AA2024-T3 AIRCRAFT ALLOY THROUGH SYNERGISTIC ANODIZATION AND CERIUM CONVERSION COATING. PART I: PERFORMANCE IN MODEL CORROSIVE MEDIUM

The present study is devoted to the monitoring of the performance of AA2024-T3 specimens, after the formation of Anodic Aluminum Oxide (AAO) layer and/or deposition of a Ceruim Conversion Coating (CeCC), obtained at 20°C and 50°C, respectively. Although both methods are well described in the literature, there is no sufficient information regarding the effect of their combination on their behaviour in corrosive media. The performance of the respective specimens was elucidated after 24 h of exposure to 3.5 % NaCl model corrosive medium (MCM) by means of Electrochemical Impedance Spectroscopy (EIS) and acquisition of Potentiodynamic Scanning (PDS) curves. Since the combined AAO/CeCC coating primers revealed superior barrier properties, the respective specimens weresubjected to long-term corrosion tests of up to 672 h of exposure to the MCM to evaluate their durability. The results revealed the synergistic effect of the combination of the surface treatment procedures on effective corrosion mitigation.

Discerning the effect of various irradiation modes on the corrosion of Zircaloy-4

Using proton irradiation, this study investigates the individual influence of several factors on the corrosion kinetics of Zircaloy-4 in a hydrogenated water environment simulating a Pressurized Water Reactor (PWR). Using both simultaneous irradiation-corrosion and autoclave corrosion, we separately examine (i) the effect of pre-irradiation on modifying the structure of the material, (ii) the impact of irradiation on creating defects in the growing oxide layer during corrosion, and (iii) the influence of irradiation on increasing the corrosion potential through radiolysis during corrosion. To replicate the neutron-irradiated microstructure, two proton pre-irradiation schedules were employed: Schedule 1 (isothermal irradiation at 350°C to 5 dpa) to simulate high-temperature PWR conditions, and Schedule 2 (two-step process: irradiation to 2.5 dpa at -10°C followed by 2.5 dpa at 350°C) to simulate lower temperature PWR and Boiling Water Reactor (BWR) conditions. Long-term autoclave corrosion testing for 360 days at 320°C revealed no significant difference between unirradiated samples and those pre-irradiated according to either schedule, with all samples exhibiting sub-cubic kinetics within the pre-transition regime. Pre-irradiated samples underwent Simultaneous Irradiation Corrosion (SIC) tests, corroding in 320°C water while being irradiated with protons. Corrosion was found to accelerate in all SIC-tested samples relative to autoclave conditions, with the greatest increase observed in non-pre-irradiated regions of the samples. Pre-irradiation with either schedule resulted in a slower corrosion rate compared to non-pre-irradiated regions under SIC conditions. The degree of radiolysis observed in the SIC tests surpassed typical PWR conditions, approaching levels found in BWRs. Radiolysis products were identified as a primary contributors to accelerated corrosion, corroborated by radiolysis bar tests. These findings underscore the intricate interactions between irradiation, corrosion, and water chemistry in determining Zircaloy-4 corrosion kinetics within nuclear reactor environments.

Investigation into the long-term alkali resistance of basalt fibers

To more accurately simulate the alkaline environment of basalt fiber in cement-based materials, this study innovatively employs the benchmark cement supernatant as the alkaline solution for the long-term corrosion testing of basalt fiber (BF). Additionally, through mechanical performance testing of mortar containing basalt fiber at different ages, the study reveals the corrosion behavior of basalt fiber in an alkaline environment. The results indicate that basalt fiber undergoes corrosion in the benchmark cement supernatant, where the OH− ions in the solution react with SiO2 in the basalt fibers, thereby disrupting the silicate framework of the fibers and causing pitting corrosion on the fiber surface. The black and white binarization analysis of the SEM images of BF7 after 360d erosion revealed that the corrosion pits covered 31.50 % of the fiber surface area, indicating severe corrosion. Furthermore, the study on the long-term mechanical properties of basalt fiber mortar demonstrated an initial increase in performance, followed by a gradual decline as the curing age progressed. Notably, after 360d of curing, the flexural strength of basalt fiber mortar was lower than that at 30d. For instance, the 360d flexural strength of BF1-0.1 and BF7-0.1 decreased by 18.85 % and 14.54 %, respectively, compared to 30d. This decline is primarily attributed to the corrosion of basalt fibers in alkaline environments, leading to a decrease in their mechanical properties. Therefore, it is essential to enhance the alkali resistance of basalt fibers when used in cement-based materials.

Revealing the environmental-assisted degeneration mechanism of an Al-containing dual-phase high entropy alloy in supercritical water

A dual-phase high entropy alloy (DP-HEA) containing 7.82 wt% Al was synthesized to withstand corrosive supercritical water. The long-term corrosion and quasi-static tensile tests reveal superior resistance to such environmental-assisted degeneration. The outstanding corrosion resistance can be attributed to the high aluminum content in B2 phase, which forms a continuous Al2O3 layer for protection, while the FCC phase is selectively corroded. Under external stress, stress corrosion cracking (SCC) initiates from surface oxide and penetrates uncompact mixed Cr/Al-rich oxide in deteriorated FCC regions or corroded phase interface, though network-shaped B2 can inhibit SCC propagation, which supports the brittle film rupture model.

Conformal growth of B/N modified graphene on metal strings by chemical vapor deposition for robust protection

For string-plucked instruments, the metal strings are always subjected to sweating corrosion and ambient oxidation during the daily use. A specifically thin protection coating, which will not alter its timbre and tone, is highly desirable. In this study, a two-dimensional (2D) coating of B/N-modified graphene (BNG) films is proposed to deposit on the surface of Cu alloy strings via chemical vapor deposition (CVD) as a corrosion barrier. Through providing appropriate amount of B/N dopant, conformal growth of BNG films on Cu alloy string substrate with sharp step-terraces topography can be optimized, and largely improving its robust anti-corrosion performance in both short-term electrochemical and long-term ambient corrosion tests for evaluation. On one hand, the conformal coupling between in-situ grown BNG and Cu alloy string can form a strong interaction which limits the interfacial diffusion of corrosive species. On the other hand, once the defects oxidation is initialized, B/N modified graphene can reduce its conductivity, then suppressing the electrochemical corrosion in the long-term protection. With the insights and understanding of in-situ coating method and the enhanced anti-corrosion mechanisms, this work will extend the potential applications of 2D materials as an atomic-thick protectioncoating for some special devices and instruments.

Optimization of Anodizing Condition for Mg-14mass%Li-3mass%Al Alloy

Mg-Li system alloys also has excellent cold-workability compared to commercial hcp-structured Mg alloys. However, Mg-Li alloys have poor corrosion resistance because not only that is Mg-based alloy but Li as a major alloying element is a less noble metal. For example, Mg-Li alloy sheet indicates high corrosion rate and exfoliation corrosion as a result of long-term corrosion test. The authors reported Mg-14 mass%Li-3 mass%Al alloy has the highest corrosion resistance in β-type solid solution alloy. Even though the optimized alloy composition, the alloy does not have enough corrosion resistance for practical use. In this study, anodized coating on Mg-Li alloy using phosphate solution was investigated. Anodizing of Mg-Li alloy facilitates the dissolution of substrate because of high Li concentration in this alloy. Therefore, the anodizing conditions were widely examined. As a result, the coating with approximately 15-20 μm of the surface layer was successfully formed. The surface layer was composed of MgAl2O4 and some phosphorus compounds. The thickness of anodized layer varied with the anodizing conditions. The dense surface layer was formed at a certain anodizing voltage and the corrosion resistance of anodized Mg-Li alloys was improved. However, the surface has some cracks and large flaky compounds. The formation mechanism of dense layer during anodizing were discussed.

Epoxy Coatings Doped with (3-Aminopropyl)triethoxysilane-Modified Silica Nanoparticles for Anti-Corrosion Protection of Zinc

Epoxy (EP) coatings containing silica (SiO2) and (3-Aminopropyl)triethoxysilane-modified silica (SiO2-APTES) nanoparticles were prepared via the dip-coating technique on a zinc substrate. A detailed study was performed regarding their incorporation into the matrix, followed by the investigation of the newly obtained organic–inorganic hybrid coatings’ anti-corrosive properties. The two methods of embedding the nanoparticles were (I) modification of the silica nanoparticles with APTES followed by their introduction into the epoxy resin, and (II) functionalization of the silica nanoparticles in the epoxy gel before the addition of the hardener. It was observed that through the second method, the coating was homogeneous, with no sign of agglomerates. The nanoparticles were subjected to morpho-structural and physical–chemical analysis using Fourier-Transform Infrared Spectroscopy and Transmission Electron Microscopy, while the coatings were examined through Scanning Electron Microscopy and Energy-Dispersive X-Ray Spectroscopy, contact angle measurements and adhesion tests. The anti-corrosive performance of epoxy-coated zinc was analyzed using electrochemical impedance spectroscopy and polarization curves to investigate the impact of silanized SiO2 nanoparticle incorporation. Based on long-term corrosion testing, the epoxy-SiO2-APTES composite coatings showed a higher corrosion resistance than the undoped epoxy layer.

Stability assessment of alumina and SiC based refractories in a high temperature steam environment as potential thermal energy storage materials

Solar energy can be utilized not only for electricity generation but also for synthetic fuel production, making it a versatile option in the transition to a low-carbon and sustainable energy system. However, to enable economically viable solar fuel production, the development of efficient thermal energy storage (TES) materials is crucial. Ceramic materials have been identified as a potential solution for high-temperature TES applications. In this study, two commercially available refractories, alumina coated recrystallized silicon carbide and alumina-based refractory were investigated for their stability under long-term steam corrosion tests to evaluate their suitability as TES materials for a potential TES unit. X-ray diffraction (XRD) revealed that recrystallized silicon carbide is composed of two different SiC polytypes (moissanite 6H and moissanite 4H) while alumina-based refractory contained corundum and mullite. Upon being exposed to steam, both materials exhibited distinct characteristics. SiC experienced significant mass gain, a subtle lightning of its surface color and erosion of a porous alumina coating on the SiC. Amorphous silica phases were detected as an indication of oxidation of SiC from X-ray diffractrograms. These remarkable changes clearly indicate that SiC is unsuitable for use in a potential thermal energy storage (TES) unit. On the other hand, there was no significant visual changes in the alumina-based refractory and the weight change was only marginal after corrosion tests. However, XRD indicated mullite completely disappeared after steam corrosion tests possibly due to its decomposition into Al2O3 and Si(OH)4.

Effects of Cu on the corrosion resistance of heat-treated weathering steel in a marine environment

The effects of Cu element on the microstructure evolution and the corrosion resistance of the heat-treated NiMo weathering steel were systematically investigated, with revealing the corresponding atomic mechanism in this work. Cu-rich precipitates (ε-Cu) with face-center cubic structure were detected in the steel after austenitizing at 1200 °C for 2 h and continuously cooling in air. ε-Cu increased the corrosion sensitivity of steel attributing to its semi-coherent feature with matrix, and further decreased the rust layer protectiveness owing to its low participation degree in the CuFeO2 formation process during long-term corrosion tests. Cu dissolved in matrix after the austenitizing and the continuous cooling in water increased the corrosion potential of steel and the CuFeO2 content in rust layer, ignoring the adverse impacts on matrix caused by the micro lattice strain of Cu atoms.

Designs of Corrosion Modules for Long-Term Corrosion Tests of Canister Materials in Aerobic and Anaerobic Underground Water

Corrosion modules simulating the engineered barrier system were designed in this study for long-term-corrosion (LTC) testing of canister materials under aerobic and anaerobic conditions. The LTC module for aerobic conditions was designed as a bath-type container with flowing underground water extracted from the Korea Underground Research Tunnel. Five types of metallic disks, that is, rolled Cu, Type 304 stainless steel (SS), Titanium Grade 2 (Ti-G2), cast iron (CI), and Cu coating, were embedded into bentonite and maintained at different temperatures. After 3 years of testing under aerobic conditions, the corrosion rates of CI and Cu were estimated to be 1.9 μm/year and 550 nm/year, respectively. The SS and Ti-G2 exhibited a better corrosion rate of 6 nm/year. The LTC module for anaerobic conditions was developed in a vessel-type cylindrical container to allow it to settle in the boreholes. Four coin-shaped disks of each metal were embedded in bentonite, which was subsequently stacked in the cylindrical vessel. The vessels were placed in boreholes at a depth of 300 m. The Cu corrosion rate after 6 months of LTC testing under anaerobic conditions was 280 nm/year. Longer LTC tests will provide a more exact corrosion rate.

Localized Corrosion of High-Grade Stainless Steels: Grade Selection in Chlorinated Seawater

Chlorination is widely used in seawater systems to avoid fouling and associated microbial-induced corrosion. Free chlorine is a strong oxidizing agent that prevents biofilm formation on immersed surfaces when used above a certain content. However, the presence of residual chlorine associated with the relatively high chloride content in seawater significantly increases the risk of localized corrosion for most stainless steels. In the present study, a module initially developed to quantify the formation of electroactive biofilms on stainless steels has been used to assess the corrosiveness of chlorinated seawater. Both the electrochemical potential and the cathodic current were measured on super-duplex stainless steel as a function of residual chlorine levels and seawater temperatures. In parallel, long-term localized corrosion tests have been performed in simulated environments to assess the environmental limits for the safe use of high-grade stainless steels in chlorinated seawater. It includes crevice corrosion exposure tests using adapted ISO 18070:2015 crevice formers and internal tube pitting corrosion exposure tests in model tube heat exchangers simulating heat flux from 35°C to 170°C. The synergetic effect of residual chlorine content and temperature on the risk of localized corrosion has been quantified. Corrosion resistance properties are correlated to the electrochemical monitoring data, and the environmental limits of selected base materials stainless steels have been established for duplex stainless steel UNS S32205, super-duplex stainless steel UNS S32750, hyper-duplex stainless steels UNS S32707 and UNS S33207, and the high-grade austenitic stainless steel UNS S31266.

Effect of plasma sprayed flyash based composite coatings on corrosion resistance

With the aim of exploring the possibility of achieving a low-cost thermal spray coating to prevent wear, erosion and corrosion. In the current study, flyash-Al2O3 and flyash-SiC composite coatings were effectively created using the air plasma spray process on substrates of Al6061 alloy. NiCr material is used as the bond coat to improve the bond strength between the coat and the substrate. Taguchi's DoE method is applied to for spray process parameters optimization. In addition, the developed coating is subjected to microstructure analysis and long-term immersion corrosion testing (1 year) in an aqueous environment to assess corrosion properties.The results revealed that the over a certain test period, the developed flyash-SiC coating has greater corrosion resistance than the uncoated and flyash-Al2O3 coated Al6061. It is noticed that the corrosion resistance of the flyash-Al2O3 coating shifts to a negative value with respect to the uncoated substrate. The uncoated sample is extensively pitted and locally corroded, as shown by the SEM image of the corroded surface. Flyash-corroded Al2O3's surface exhibits extensive degradation in the form of peeling, breaking, and cracking of the splats. With flyash-SiC composite coating a very minor corrosion splat deterioration is seen.

Dopamine self-polymerized sol-gel coating for corrosion protection of AZ31 Mg Alloy

Mg alloys have excellent mechanical and physical properties. Unfortunately, the poor corrosion resistance becomes the main disadvantage of the application of such materials in aqueous and atmospheric media. Although the sol-gel-based coating has attracted significant attention for alloys in corrosion protection, most of the existing sol-gel coatings are unable to give a long-term protection for the substrate against corrosion in saline solutions due to micro-/ nano-pores contained in its glassy sol-gel networks. To address this issue, a new sol-gel coating was prepared by utilizing the strong adhesion property of polydopamine (PDA) to provide a highly condensed sol-gel-based coating (PDA@sol-gel) on Mg alloy AZ31. Long-term corrosion testing by electrochemical impedance spectroscopy in aqueous 0.1 M NaCl indicated that the prepared PDA@sol-gel coating exhibited a substantially improved corrosion protection performance with a test duration of over 20 days. In comparison, the unmodified coating failed after 3 days of immersion in aqueous NaCl. The improved anti-corrosion performance may be attributed to the self-polymerized PDA filling the micro-/ nano defects in the cross-linked network of the SiO2 sol-gel, which greatly improves the compactness of the coating. This work presented a new approach to significantly improve the corrosion protection performance of magnesium alloys by dopamine-modified sol-gel coating, which can find ample applications in a wide range of industries.

Water-Immersion Stability of Self-Compacting Potassium Magnesium Phosphate Cement Paste

For the repair of narrow cracks in concrete, the potassium magnesium phosphate cement (MKPC)-based material paste should have high fluidity and self-compacting ability, making it convenient for pouring and compacting. A self-compacting MKPC paste that meets the index requirements recommended by the European Federation of National Associations Representing for Concrete (EFNAFC) was prepared by increasing the water-cement ratio and adding water glass and fly ash (FA). Specimens of self-compacting MKPC paste were subjected to long-term water corrosion tests, which found that those high-fluidity MKPC paste specimens (reference sample M0) that were produced with only an increased water-cement ratio lost 15-30% of their strength. The residual ratio of folding to compression was 84.6%, and the volume expansion rate was 7.78 × 10-4 after immersion in water for 560 days. The strength residual rate of MKPC slurry (M1) modified by sodium silicate and fly ash is over 90% after 560 days of immersion in water, and the residual rate of flexural-compressive ratio is 101.3%, which meets the requirements of hydraulic cement-based materials. The volume expansion rate of M1 is 5.19 × 10-4, which is 67% of the reference sample M0 with the same water immersion age.

Multi-Elemental Coatings on Zirconium Alloy for Corrosion Resistance Improvement

Zirconium alloys are commonly used as a cladding material for fuel elements in nuclear reactors. This application is connected with zirconium alloy’s good resistance to water corrosion and radiation resistance under normal working conditions. In the case of severe accident conditions, the possibly very fast oxidation of zirconium alloys in steam or/and air atmosphere may result in the intense generation of hydrogen and explosion of the hydrogen oxide mixture. The development of a solution to minimize the aforementioned risk is of interest. One of the actual concepts is to improve the oxidation resistance of Zr alloy cladding with protective coatings. This study aimed to develop, form, and investigate new coatings for zirconium alloy Zry-2. Multi-elemental Physical Vapour Deposition (PVD) coatings with Cr, Si, and Zr were considered for Institute of Nuclear Chemistry and Technology) INCT as corrosion protective coatings for nuclear fuel claddings. Heat treatment at 850–1100 °C/argon, air oxidation processes at 700 °C/1–5 h, and a long-term corrosion test in standard conditions for Pressure Water Reactor (PWR) reactors (360 °C/195 bar/water simulating the water used in PWR) were carried out. Initial, modified, and oxidized materials were characterized with Scanning Electron Microscopy (SEM) (morphology observations), Energy Dispersive Spectroscopy (EDS) (elemental composition determination), and X-ray Diffraction (XRD) (phase composition analysis). Slower oxidation processes and a smaller oxidation rate, in the case of modified material investigations, were observed, as compared with the unmodified material. The obtained results displayed a protective character against the oxidation of formed layers in the defined range of parameters in the process.

Evaluating Corrosion Behaviour of Copper Under Deliquescent Drying/Wetting Cycles in Humid Air Condition

Most nuclear safety agencies around the world agree that deep geological repositories (DGRs) constructed hundreds of meters below ground in stable host rock formations are viable solutions to safely isolate used nuclear fuel. In Canada, the DGR design involves storing used nuclear fuel in sealed copper coated used fuel containers (UFC) surrounded by highly compacted bentonite blocks (HCB) ~500 m underground. Shortly after emplacement, heat generated by radioactive decay of the used fuel will warm the UFC and its surroundings, desiccating the HCB and decreasing moisture on the container surface. As water vapour is driven from the UFC surface, the presence of minor amounts of dissolved salts may cause droplet formation prior to complete evaporation, during which deposits of salts may be left behind on the UFC. Later, as conditions evolve and the relative humidity increases and the temperature decreases, condensation of liquid water on the UFC surfaces will produce droplets again, due to the deliquescence of minor salt deposits. In either the wetting or the drying scenario, secondary spreading and spatial separation of anodic and cathodic reactions and consequent non-uniform corrosion could be possible, due to the droplet geometry.To investigate this scenario, the quartz crystal microbalance (QCM) technique is being used. The QCM initially consists of a quartz plate, covered by gold electrodes on both sides where a layer of copper is deposited on the crystal by using magnetron sputtering. In this technique, the change in the resonance frequency of a vibrating quartz crystal is correlated to its mass change due to the corrosion process. To investigate the effect of salts and their deliquescence behaviours, different salts (NaCl, CaCl2, and MgCl2) and CR10-E simulated groundwater were loaded on the copper surface using an inkjet printer, and then corrosion tests were performed at different temperatures and relative humidity (RH) values. In parallel, a set of long-term vapour-phase corrosion tests was performed on wrought and cold-sprayed copper coupons at 75 °C and different RH values. As part of the post-experiment analysis, the corrosion products were analyzed using a suite of surface analysis techniques, including optical microscopy, Raman spectroscopy, and scanning electron microscopy (SEM).The results from QCM experiments at RH values below salts deliquescence point showed a low mass change that could correlate with less corrosion in comparison to the experiments at RH values above salts deliquescence point. It’s worth noting that even at RH values below the deliquescence point of the salts, a trace of corrosion was observed which could be indicative of the presence of monolayers of water on the surface. The results obtained from NaCl and CR10-E exposure conditions showed higher mass change and therefore higher corrosion in comparison to CaCl2 and MgCl2 salts. As for the long-term vapour-phase corrosion tests, Raman spectroscopy confirmed the presence of CuO and Cu2O on the surface as corrosion products. Further surface characterizations and mass loss measurements are underway to determine the extent of corrosion on the copper coupons.

Corrosion Characteristics of Bronze Artifacts Excavated from the Songguk-ri site in Buyeo According to Alloy Ratio and Manufacturing Techniques During the Goryeo Dynasty

A comprehensive analysis of the corrosion characteristics of excavated bronze artifacts was conducted according to their alloy ratio and microstructure. Corroded by various factors, which resulted in different corrosion characteristics. Among these, corrosion may occur in the excavated bronze due to the difference in the alloy ratio, which is an internal factor. In this study, we tried to confirm the corrosion characteristics of the excavated bronze artifacts excavated from Songguk-ri site in Buyeo according to their alloy ratio and microstructure through a comprehensive analysis. The corrosion characteristics of the excavated bronze artifacts differed depending on the alloy ratio and microstructure, whereas bronze samples subjected to the corrosion tests were the same regardless of the alloy ratio and microstructure. Through this, the corrosion characteristics of excavated bronze artifacts can be determined based on the additional effects on pH, corrosion factors, and time in the burial environment which can affect metal ion movement, in addition to alloy ratio and microstructure. In the future, if a burial environment similar to the actual remains and a long-term corrosion test is conducted, it will be possible to confirm the corrosion mechanism as well as the corrosion characteristics of the excavated bronze artifacts.

Designs of Corrosion Modules for Long-Term Corrosion Tests of Canister Materials in Aerobic and Anaerobic Underground Water

Designs of Corrosion Modules for Long-Term Corrosion Tests of Canister Materials in Aerobic and Anaerobic Underground Water

Effect of powder size on strength and corrosion behavior of Mg66Zn30Ca4 bulk metallic glass

Biomedical biodegradable materials have attracted widespread attention since they are naturally decomposed in the body. In particular, Mg-Zn-Ca systems are the most popular degradable metal materials, owing to their good biocompatibility and mechanical properties. Meanwhile, bulk metallic glass (BMG) is known to exhibit a series of advantages over crystalline alloys (including higher strength, hardness, and corrosion resistance), owing to the long-range disorder in atomic arrangement. In this study, Mg66Zn30Ca4 BMG samples with average particle sizes of 22.9, 45.4, and 62.4 µm were prepared via spark plasma sintering (SPS), and the influence of powder particle sizes on mechanical strength, hardness, and corrosion behavior was investigated. The results showed that the strength and hardness decreased with an increase in the particle size. Based on the long-term corrosion test, it can be concluded that a large particle size is beneficial to the corrosion resistance of materials.

Aluminum Protection by Using Green Zirconium Oxide Layer and Organic Coating: An Efficient and Adherent Dual System

In this work, the use of ZrO2 nanocoating in aluminum substrates, generated by controlled electrochemical chronoamperometry in hexafluorozirconic acid solutions (H2ZrF6·5H2O), resulted in a lower porous films than that obtained by chemical conversion coating. After the application of an epoxy coating, long-term cyclic immersion corrosion tests and scratch tests proved the superior protection of the dual system and the coating lifespan, thanks to the enhanced adhesion of ZrO2 intermediate layer and the organic coating. As zirconium-based electrolytes are considered more friendly bath if compared to that of other conversion coating processes, like chromating, phosphating or anodizing processes, the study opens new insights to the protection of structural metals in sectors such as automotive, naval and aerospace industries. The main advantages are the employment of lightweight intermediate pre-treatment (nanoscale), compared to conventional ones (microscale), and reduction of waste slurry (electrolyte bath free of additives).