C.M. Abreu

University of Vigo | UVIGO · Department of Materials Engineering, Applied Mechanics and Construction

The influence of annealing treatment on the microstructure and the corrosion behaviour of a complex bronze Al-Ni alloy was analysed. The microstructural characterization after thermic treatment shows that the retained β-phase disappears and the KII-phase undergoes a spheroidization process. Moreover, there is an augmentation of K-phase precipitates...

This work is focused on the evaluation of the corrosion behaviour of an AA2024-T351/SiC surface composite produced by friction stir processing (FSP). The surfaces composite show a quite homogenous distribution of the SiC particles in the stir zone, together with a significant grain size reduction as Electron Backscatter Diffraction analysis confirm...

Friction stir processing (FSP) is applied to create surface metal–matrix composites (SMMCs). This study aims to develop defect-free surface composites on AA2024 aluminum alloy with structural hardening (T351). It focuses on the effect of the number and direction of FSP passes on the particle distribution and microstructural modifications of the pro...

This work reports the corrosion behavior of the AA7075 aluminum alloy under two different tempers (T6 and T73) after nitrogen implantation in 0.5 mol·L⁻¹ NaCl solution. A combination of Electrochemical Impedance Spectroscopy and surface microstructure characterization was used to analyze the effects of nitrogen implantation on corrosion resistance....

Friction stir processing (FSP) has been used to produce metal matrix composites by incorporating reinforcement particles in an AA6061-T6 matrix. Two types of particles (Al2O3 and SiC) were tested. Powder was placed into a mechanized square section groove on a plate surface and then sealed before FSP. This study investigates the effect of several st...

Metal matrix composites (MMCs) are a new class of materials that exhibit good wear resistance and high hardness. Since the wear resistance and hardness are surface properties, if the reinforcing particles are only added to the surface layer instead of bulk, the wear resistance and surface hardness can be improved without sacrificing the bulk proper...

In this study, we applied potentiodynamic polarization to the analysis of surface corrosion in a 2017-T4 alloy during a stress corrosion cracking (SCC) test in 1 m NaCl solution. A constant load SCC test was chosen, classifying the applied load into three categories – no load, medium load, and high load – with the material's yield strength as a max...

In this research work, eight coatings consisting of primers, topcoats and combinations of primers/topcoats were evaluated. Salt spray test (SST) and impedance measurements were carried out for evaluating macroscopic failures (blistering, adhesion, etc.) and the electrochemical behaviour of the referred coatings, respectively, which were supported b...

The deposition rate of Cl- and SO42- ions involved in the corrosion under marine aerosol influence was monitored by using different retention methods: alkaline sulfation plate, wet candle and dry plate. It is known that the Cl-/SO42- ratio in sea water and in marine aerosol is near 7. Hence, by using this relationship and the experimental data of d...

The presence of Zn pigments combined with the barrier effect of a multilayer paint system (Zn rich epoxy/epoxy/polyurethane coated steel) has mitigated the disbondment process in natural and overprotection cathodic conditions. The evaluation of the protective properties was carried out by means of EIS measurements. The samples submitted to one week...

Waste valorisation is a topic in the limelight since environmental concerns are furthering a better use of raw materials. Annually, millions of tons of waste tyres are generated worldwide and represent a great environmental threat that could be used in the development of novel materials for effective protection against steel corrosion. In this work...

Metallurgical analyses and chemical characterizations were carried out on historical cannonballs from the Fortress of San Juan de Ulúa, Veracruz, México. Cannonballs dating from the 18th and 19th centuries share metallurgical characteristics similar to those of material coming from a shipment of ammunition found in the wreck of a sunken French ship...

A strategy based on the use of an inert ionic liquid (IL) has allowed the study of the electrolyte diffusion process in a polysiloxane-based coating applied on steel. The selection of 1-ethyl-3-methylimidazolium ethylsulfate, acting as nonaqueous medium, made it possible to evaluate the protective performance of polysiloxane coating under dry condi...

The present work reports the improvements in corrosion resistance and tribological properties achieved after Nitrogen ion implantation into aluminium alloy AA7075 subjected to two different tempers, T6 and T73.Nitrogen implantation at a nominal dose of 2 × 1017 ions/cm2 and at an accelerating voltage of 50 keV produced an increase of the surface ha...

In this work, five coating systems combining different surface treatments were applied to steel samples and compared with a model system used in civil structures. The corrosion behaviour under an aggressive marine environment was evaluated for two years of exposure. An excellent anticorrosive performance was demonstrated for a phosphate conversion...

In this work, the suitability of the ionic liquid 1-ethyl-3-methyl imidazolium ethylsulfate (C2C1imC2SO4) for improving the anticorrosive behaviour of zinc rich paints (ZRP) has been demonstrated. The electrochemical performance of the coating has been evaluated by means of electrochemical impedance spectroscopy. These data allowed validating the u...

In this work, the deposition rate of two of the main ions involved in the corrosion caused by marine aerosol (SO42– and Cl–) were monitored for three years, using three different collection methods: alkaline sulfation plate, wet candle, and dry plate (ASP, WC, and DP). The deposition rate of Cl– and SO42– evidenced significant differences depending...

The present work analyses the effect of molybdenum implantation at the nominal dose of 2×1016 Mo+ ions·cm−2 and acceleration voltage of 100 keV, on the passive layer formed on different tempers (T6 and T73) of AA7075 aluminium alloy. XPS and glancing angle X‐ray diffraction were used to characterize the implanted surface. The results obtained sugge...

The aim of the present work is to study the effect of nitrogen and molybdenum implantation in the tribological behaviour of the AA7075 alloy subjected to different structural hardening treatments (T6 and T73).Wear tests, nanoindentation and roughness measurements by interferometric profilometry have been performed. Sliding wear experiments were per...

The effect of Mo+ implantation on corrosion properties of AA 7075 (T6 and T73) has been studied. The induced modifications in the surfaces have been analysed by XPS and GAXRD. EXCO tests and electrochemical DC and AC techniques have been used to characterize the localized corrosion resistance. The effect of implantation is highly dependent on the a...

The present work analyzes the chemical effect of nitrogen implantation on the passive layer formed on different tempers of AA7075 aluminium alloy, T6 and T73. The experimental results from XPS depth profiles show that the air-formed passive oxide, on both tempers, is mainly formed by Al2O3, highly hydrated, with Mg2+ and small amounts of Zn2+. The...

This paper reports the study of the effect of nitrogen implantation on the localized corrosion resistance of the passive layers generated on different tempers of AA7075 aluminium alloy.Cyclic potentiodynamic polarization has been employed to analyze the resistance to localized corrosion of the alloys in a chloride medium, whereas exfoliation corros...

The objective of this work is to investigate the effect of Mo implantation at a dose of 3.5 × 1015 ions/cm2 on the corrosion resistance on 304L and 316 austenitic stainless steels. Electrochemical measurements were used to investigate the corrosion behavior of the alloys in sulfuric acid in presence of chlorides. The obtained results show that Mo i...

Two austenitic stainless steels have been implanted at 150 keV with Mo at a fluence of 3.5×1015 ions/cm2. The effects of ion implantation in the chemical composition of the passive films was evaluated by x-ray photoelectron spectroscopy (XPS) and glancing angle x-ray diffraction (GAXRD) was used to determine the induced structural modifications. Th...

Research on the effect of ion implantation on the corrosion behaviour of metals has been carried out for years, but some difficulties arise in the comparison of the obtained results due to variations in experimental conditions (alloys, surface preparation, doses, experimental techniques⋯). This work tries to overcome those differences, presenting t...

Red mud (RM) is the main by-product of the Bayer process for alumina extraction from bauxite, and grey slurries (GS) are generated during the granite rocks transformation processes. The huge volume of those wastes generated every year suppose a serious environmental problem. Recent works by our group demonstrate the efficiency of both types of muds...

In this paper the electrochemical behaviour of AISI 304L stainless steel implanted with nitrogen is studied in alkaline media and chloride-containing media, and it is compared with the behaviour of the unimplanted material. Implantation was done at a saturation dose (4 x 10(17) ions cm(-2)) at an acceleration voltage of 150 keV. The results show a...

Surface analysis techniques (XPS and grazing incidence X-ray diffraction GIXRD) and electrochemical techniques have been combined to elucidate the effect resulting from Cr+ and N+ co-implantation in the formation and evolution of passive layers generated on two different stainless steels (AISI 430 and AISI 304L) in alkaline medium. The results show...

This work is focused on a detailed analysis of passive layer formed on AA2024-T3 aluminum alloy, in unmodified and nitrogen-implanted conditions. This study is the first step in analyzing the possible beneficial effect of nitrogen implantation in the simultaneous improvement of the tribological properties and pitting resistance. The implanted surfa...

AISI 304L and SAF 2205 stainless steel samples were implanted with chromium plus nitrogen at saturation dose in order to improve their hardness and wear properties. Consequently, the passive layer is modified so that besides the detected presence of CrN, a clear decrease in the amount of Fe oxides forming the passive layer is detected in both steel...

Porrifio is a well known zone of quarry and stone working of the SW of Galicia, Spain. In granite's working processes 3 x 10(5) ton year(-1) of granite powder are generated in this area, causing an important environmental problem. This dust has proved to be an efficient addition to high-strength concrete to improve mechanical properties. Neverthele...

This chapter presents a study in which the influence of chlorides on the films electrochemically formed on SAF 2205 in NaOH is examined as a function of the immersion time in NaOH 0.1M + NaCl 0.5M solution. The characterization of the oxide film electrochemically developed on a SAF 2205 in alkaline media is achieved by cyclic voltammetry and electr...

This chapter presents a study in which the conductivity of air-formed films on Fe-Cr-Ni alloys is studied in alkaline solution by using impedance spectroscopy. It aims to study the role nickel (Ni) on the growth and conducting properties of the oxide layers in various alloys. Specimens of 1.1 x 1.1 cm were cut, wet ground, polished to 6 μm diamond...

This chapter presents a study in which the effect of cerium ion (Ce+) implantation on the electrochemical behavior of SAF 2205 DSS is analyzed in alkaline medium. The results demonstrate that the change in the electrochemical behavior of duplex stainless steel is due to the modifications that cerium implantation promotes in the passive layer and in...

This chapter presents a study on the effects of soluble aluminum in the corrosion behavior of iron in alkaline media. Solutions are prepared by dissolving Al foils in NaOH O.IM to reach the solubility limit, which was about 13.5 mg.L-1. The tested material was pure iron (99.9%) obtained from Goodfellow as rods. The exposed area was the cross sectio...

This study analyses the influence of Ni in the electrochemical behaviour of three different stainless steels in alkaline medium. The studied steels have increasing Ni content: AISI 430, AISI 304L and AISI 316. The obtained results are compared with those of a nickel base alloy (Ni > 42%, w/w) and a pure Ni electrode. Electrochemical impedance spect...

Surface analysis techniques (XPS and grazing incidence X-ray diffraction GIXRD) and electrochemical techniques are combined to elucidate the effect resulting from N+ single-implantation and Cr+ and N+ coimplantation in the formation and evolution of passive layers generated on AISI 430 steel in alkaline medium. Nitrogen implantation leads to CrN to...

In this work, an insight into the effect of surface roughness in the composition and evolution of the oxide film electrogenerated on an austenitic stainless steel substrate is presented. The obtained results point out the importance of Ni on the oxide layers formed in alkaline media, which can condition their resistance to chloride attack. Polished...

In this research, the behaviour and evolution of passive films generated on AISI 304L are studied for a long immersion time in chloride containing media. A combination of electrochemical (cyclic voltammetry and electrochemical impedance spectroscopy) and surface analysis techniques (AFM and XPS) is used in this work in order to analyse the changes...

Passive films formed on AISI 316 in deaerated 0.1 M NaOH solution were studied using cyclic voltammetry, impedance spectroscopy and X-ray photoelectron spectroscopy techniques. The impedance spectra were recorded between 10 kHz and 1 mHz as a function of the electrode potential. Impedance spectra for a two-electrode cell were also recorded between...

Evolution of the passive films formed on AISI 304L and duplex stainless steel SAF 2205 in NaOH 0.1 M was investigated using cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). Special attention is paid to the effect of Mo in the generation of the films. Results point out to the stabilising ef...

In this work X-ray photoelectron spectroscopy studies and electrochemical techniques are combined to elucidate the effect of Ce and Cr implantation in the formation and evolution of passive layers generated by potentiodyinamic cycling on AISI 304L steel in alkaline medium. Cerium implantation promotes the formation of a thinner and more protective...

This work studies the effect of chromium implantation on the development of passive layers generated electrochemically in alkaline medium over two stainless steels. The XPS analyses show that the layers generated on the implanted steels present less thickness together with similar composition compared to the unimplanted steels layers. However, SEM...

This work studies the effect of chromium implantation on the development of passive layers generated electrochemically in alkaline medium over two stainless steels. The XPS analyses show that the layers generated on the implanted steels present less thickness together with similar composition compared to the unimplanted steels layers. However, SEM...

The electrochemical behaviour of films formed on AISI 316 and AISI 304L by cyclic voltammetry in alkaline medium is studied by EIS. Impedance spectra were obtained each 100mV from –1.057V to 0.443V (vs.Hg/HgO), in order to scan the different activity regions detected in voltammetric studies, i.e.: iron activity, passivity and Cr-Ni-Mo activity zone...

The present work focuses on the effect of chromium implantation on the formation and evolution of the passive layers formed on an austenitic stainless steel (AISI 304L) in an alkaline medium. Cyclic Voltammetry and electrochemical Impedance Spectroscopy have been used for this study. The characterization of the developed passive films has been perf...

Chemical treatment in solutions containing cerium compounds has been widely used for prevention of localized corrosion in aluminium alloys (pitting corrosion) as well as in stainless steels (crevice corrosion). Ionic implantation presents several advantages for stainless steels. The present paper is devoted to study the effect of cerium implantatio...

In this work X-ray photoelectron spectroscopy studies and cyclic voltammetry are combined to elucidate the effect of Ce implantation on the formation and evolution of passive layers generated on AISI 430 and AISI 304L steels in alkaline medium. The passive films develop in implanted steels result thinner and less defective than in unimplanted. This...

Chemical treatment in solutions containing cerium compounds has been widely used for prevention of localized corrosion in aluminium alloys (pitting corrosion) as well as in stainless steels (crevice corrosion). Ionic implantation presents several advantages for stainless steels. The present paper is devoted to study the effect of cerium implantatio...

The galvanic currents between carbon steel and two types of stainless steels have been studied in solutions of pH close to that of concrete. The situations analysed were passivity and active corrosion induced by chlorides. In all cases the galvanic effects recorded were of minor importance indicating that no significant risk of galvanic corrosion e...

Passive layers formed on a Ce implanted stainless steel in alkaline media are studied to clarify its beneficial effect on stainless steel corrosion resistance. An important decrease in iron and chromium activity peaks is detected by electrochemical techniques. X-ray photoelectron spectroscopy (XPS) analysis shows passive film thickness decreasing t...

The present paper is a review of the most important works developed by the Corrosion Engineering and Materials Research Group (University of Vigo), relaled to paints and the way that they protect metallic substrates. According fa the different protection rnechanism, the study was divided in two paint families: barrier coalings applied over galvanis...

The behaviour of zinc-rich epoxy paints has been studied in 3% NaCl solution. The study focuses on the influence of film thickness and zinc particle size on coating performance. Electrochemical Impedance Spectroscopy was the main technique employed to carry out the experimental work. The impedance spectra are interpreted by using a fluidised bed mo...

The present study examined the behavior of zinc-rich paints (ZRP) based on an epoxy binder in 3% sodium chloride (NaCl) solution. The study focused on the effect of some design parameters often considered in paint formulation. The paint thickness, the zinc particle grain size, and the zinc particle distribution in the paint were studied. The study...

The aim of the present work is to determine the influence that different atmospheric agents have in steel protection by zinc rich paints based on inorganic silicate binder. The presence of pollutants in the atmosphere has been simulated by periodical deposition of sulphate and/or chloride solutions on the surface of the samples. With the aim of det...

The aim of the present work is to determine the influence that different atmospheric agents have in steel protection by zinc rich paints based on inorganic silicate binder. The presence of pollutants in the atmosphere has been simulated by periodical deposition of sulphate and/or chloride solutions on the surface of the samples. With the aim of det...

Electrochemical impedance spectroscopy (EIS) in the 100kHz–1mHz frequency range was employed as the main electrochemical technique to study the corrosion protection behaviour of a zinc-rich epoxy paint in 3% NaCl solution. The EIS results obtained at the open-circuit corrosion potential have been interpreted using a model involving the impedance of...