Protection Of Metal Surfaces Research Articles

A shape-recovery polymer coating for the corrosion protection of metallic surfaces.

Self-healing polymer coatings are a type of smart material aimed for advanced corrosion protection of metals. This paper presents the synthesis and characterization of two new UV-cure self-healing coatings based on acrylated polycaprolactone polyurethanes. On a macroscopic scale, the cured films all show outstanding mechanical properties, combining relatively high Young's modulus of up to 270 MPa with a strain at break above 350%. After thermal activation the strained films recover up to 97% of their original length. Optical and electron microscopy reveals the self-healing properties of these coatings on hot dip galvanized steel with scratches and microindentations. The temperature-induced closing of such defects restores the corrosion protection and barrier properties of the coating as shown by electrochemical impedance spectroscopy and scanning vibrating electrode technique. Therefore, such coatings are a complementary option for encapsulation-based autonomous corrosion protection systems.

Self-powered metal surface anti-corrosion protection using energy harvested from rain drops and wind

Corrosion of metal surfaces, especially ships and cultural relics, is one of the most concerns in asset protection, which costs billions of dollars worldwide each year. For the protection of metal surfaces, cathodic protection (CP) has been widely used as a primary technology. However, the application of the technology results in high energy cost and more serious environmental pollutions. In this work, a self-powered CP system for metal surface protection was designed by utilizing the energy harvested from natural rain drops and wind using a flexible triboelectric nanogenerator (TENG). The TENG power-supplying system can provide a practical energy source for sustainably driving the CP process without using an external power source. Stereoscopic microscopy, AC impedance measurements, polarization test and surface tension testing were used to verify the feasibility of self-powered CP process. Our results indicate that the flexible TENG can produce highly efficient CP system for almost all metallic structures. This work not only demonstrates a highly-simple-fabrication, great-performance and cost-effect approach to protect metal surfaces from corrosion, but also develops a new self-powered electrochemical technique for CP that can be widely used in metal cultural relics, ocean engineering, industry, transportation, and so on.

How Organophosphonic Acid Promotes Silane Deposition onto Aluminum Surface: A Detailed Investigation on Adsorption Mechanism

Many research works have evidenced the importance in using inorganic–organic hybrid materials to protect metal surface or to serve as intermediate adhesion promoter layer for further coating deposition. The main aim of the present work was to elucidate the mechanism of silane deposition onto aluminum surface, in the presence of organophosphonic acid as adhesion promoter and using experimental and theoretical techniques. Transparent thin films of layered inorganic–organic composites were prepared by the sol–gel synthesis of tetraethylorthosilicate and vinyltrimethoxysilane in the presence of 1,2-diaminoethanetetrakis-methylenephosphonic acid. Aluminum surface was characterized by X-ray diffraction, SEM and XPS techniques. On the other hand, inorganic–organic coating was characterized by FTIR and XPS spectroscopies. Density functional theory was employed to evaluate three simplified molecules, orthosilicic acid (Si(OH)4), methylphosphonic acid (MePA), and Si(OH)3OMePA, by using different coordination modes, in order to approach the most stable chemical bonding between silane-phosphonic groups with modified aluminum surface (i.e., with boehmite as oxidized layer).

Use of graphene as protection film in biological environments

Corrosion of metal in biomedical devices could cause serious health problems to patients. Currently ceramics coating materials used in metal implants can reduce corrosion to some extent with limitations. Here we proposed graphene as a biocompatible protective film for metal potentially for biomedical application. We confirmed graphene effectively inhibits Cu surface from corrosion in different biological aqueous environments. Results from cell viability tests suggested that graphene greatly eliminates the toxicity of Cu by inhibiting corrosion and reducing the concentration of Cu2+ ions produced. We demonstrated that additional thiol derivatives assembled on graphene coated Cu surface can prominently enhance durability of sole graphene protection limited by the defects in graphene film. We also demonstrated that graphene coating reduced the immune response to metal in a clinical setting for the first time through the lymphocyte transformation test. Finally, an animal experiment showed the effective protection of graphene to Cu under in vivo condition. Our results open up the potential for using graphene coating to protect metal surface in biomedical application.

Initiation of Sticking during Hot Rolling of Stainless Steel Plate

Hot rolling of stainless steel is one of the most important steps in manufacturing process regarding surface quality of the product. Stabilised ferritic stainless steels are widely used in automotive and cosmetic appliances but are also concerned by sticking phenomenon. These grades, having high dry corrosion and creep resistance, are enriched in specific chemical elements such as Cr, Nb or Ti, limiting also slab oxidation during hot rolling. Nevertheless, the mastered oxidation of slab surface is a way to protect metal surface from direct contact with rolls. In order to better understand initiation of sticking, a first campaign was based on topography and rolls surface state wear analysis. This study revealed that sticking initiation is not due to the presence of roll scratches which depth is higher than oxide layer thickness. Indeed, the probability that roll scratches are deeper than oxide layer thickness is very low. In a second time, a pilot was designed, reproducing tribological conditions of a roll bite, to better understand mechanisms that initiate sticking. Keeping in mind the importance of rolls and slab surface state, this pilot is able to use specimen taking from industrial products, having the original oxide layer surface. This second study highlighted the major role of silicon oxides on scale adherence and the high heterogeneity of this scale layer in thickness and in chemical composition.

Effects of Contact Pressure, Plastic Strain and Sliding Velocity on Sticking in Cold Forging of Aluminium Billet

Hot rolling of stainless steel is one of the most important steps in manufacturing process regarding surface quality of the product. Stabilised ferritic stainless steels are widely used in automotive and cosmetic appliances but are also concerned by sticking phenomenon. These grades, having high dry corrosion and creep resistance, are enriched in specific chemical elements such as Cr, Nb or Ti, limiting also slab oxidation during hot rolling. Nevertheless, the mastered oxidation of slab surface is a way to protect metal surface from direct contact with rolls. In order to better understand initiation of sticking, a first campaign was based on topography and rolls surface state wear analysis. This study revealed that sticking initiation is not due to the presence of roll scratches which depth is higher than oxide layer thickness. Indeed, the probability that roll scratches are deeper than oxide layer thickness is very low. In a second time, a pilot was designed, reproducing tribological conditions of a roll bite, to better understand mechanisms that initiate sticking. Keeping in mind the importance of rolls and slab surface state, this pilot is able to use specimen taking from industrial products, having the original oxide layer surface. This second study highlighted the major role of silicon oxides on scale adherence and the high heterogeneity of this scale layer in thickness and in chemical composition.

Towards multiscale modelling of localised corrosion

Localised corrosion is a cause of unanticipated and sometimes catastrophic failures of equipment, transport vessels and infrastructures. Therefore, the development of modern corrosion-resistant materials and inhibitors by design is both technically and economically attractive. In the coming decades, industrial components will be engineered from molecular structures. This prospect provides the designer with a truly enormous range of choices in design, which is a situation that demands predictive tools that can link molecular structures with the final component performance. In particular, the development of alloys and inhibitors can replace the use of toxic compounds in protecting metal surfaces. To execute a tailored design programme, it is necessary to understand how corrosion and the associated processes occur from the molecular level to the component level and how the overall system behaviour emerges because of the inherent links among different scales. Therefore, in the present work, the literature on theoretical modelling of localised corrosion and related experimentation are reviewed from a multiscale viewpoint. The review addresses (a) the challenges in the theoretical formulation of the important phenomena that influence localised corrosion and (b) the hurdles facing computational methods. It is shown that (i) the existing models lack the resolution to design effective corrosion-resistant systems, (ii) the numerical strategies for linking the scales are in a state of evolution and (iii) there are gaps in the experimental characterisation of the corrosion system, particularly at the lower end of the scales. Suggestions are provided towards the construction of a multiscale model (MSM) for localised corrosion.

Fast-curing epoxyurethane coatings

Fundamental aspects of synthesis and the properties of fast-curing epoxyurethane polymeric coatings based on ED-20 (Russia), Epikote 862 (Great Britain), and Der 331 (USA) epoxy resins, industrially manufactured domestic polyesters PDA 800 and PS, polyisocyanate, and Lapramol 294 were studied. It is shown that the foreign epoxy resins can be replaced with ED-20 resin and this resin can be used to obtain high-quality fast-curing epoxyurethane polymeric coatings that can be used to protect metal surfaces.

Static failure analysis of adhesive corner joints

The present study is concerned with the failure analysis of a special type of adhesive corner joint, which is essentially a rectangular cantilever bonded to a support. A shape factor that allows correlating the static strength of two joints with different geometries is proposed. The relation is valid for adhesives with brittle–elastic behaviour and highly resistant adherends. Therefore, only a few tests performed in particular joint taken as reference are necessary for assessing the structural integrity of any similar joint with arbitrary geometry. Results from experiments performed in ASTM 1020 steel tee joints with different bonding areas are compared with model prediction showing a good agreement. The adhesive was an epoxy/ceramic composite used in the oil industry for the repair and protection of metal surfaces subjected to corrosion and chemical attach.

Ag- and Cu-doped multifunctional bioactive nanostructured TiCaPCON films

A key property of multicomponent bioactive nanostructured Ti(C,N)-based films doped with Ca, P, and O (TiCaPCON) that can be improved further is their antibacterial effect that should be achieved without compromising the implant bioactivity and biocompatibility. The present work is focused on the study of structure, chemical, mechanical, tribological, and biological properties of Ag- and Cu-doped TiCaPCON films. The films with Ag (0.4–4at.%) and Cu (13at.%) contents were obtained by simultaneous sputtering of a TiC0.5–Ca3(PO4)2 target and either an Ag or a Cu target. The film structure was studied using X-ray diffraction, transmission and scanning electron microscopy, energy dispersive X-ray spectroscopy, glow discharge optical emission spectroscopy, and Raman-shift and IR spectroscopy. The films were characterized in terms of their hardness, elastic modulus, dynamic impact resistance, friction coefficient and wear rate (both in air and normal saline), surface wettability, electrochemical behavior and Ag or Cu ion release in normal saline. Particular attention was paid to the influence of inorganic bactericides (Ag and Cu ions) on the bactericidal activity against unicellular yeast fungus Saccharomyces cerevisiae and gram-positive bacteria Lactobacillus acidophilus, as well as on the attachment, spreading, actin cytoskeleton organization, focal adhesions, and early stages of osteoblastic cell differentiation. The obtained results show that the Ag-doped films are more suitable for the protection of metallic surfaces against bacterial infection compared with their Cu-doped counterpart. In particular, an excellent combination of mechanical, tribological, and biological properties makes Ag-doped TiCaPCON film with 1.2at.% of Ag very attractive material for bioengineering and modification of load-bearing metal implant surfaces.

A study of 4-carboxyphenylboronic acid as a corrosion inhibitor for steel in carbon dioxide containing environments

4-Carboxyphenylboronic acid (CPBA) has been found to be an efficient carbon dioxide (CO2) corrosion inhibitor for steel in aqueous media. The results indicate that the addition of CPBA to CO2 containing sodium chloride solutions at a low concentration is able to retard corrosion anodic reactions, reduce corrosion current densities, increase charge transfer and total resistances, resulting in more uniform and smoother steel surfaces. These effects are attributed to the formation of a barrier layer on steel surface, which provides metal surface protection. The inhibitor was also found to mitigate corrosion by promoting random distribution of minor anodes.

Nanostructured photocatalytic coatings for corrosion protection and surface repair

Corrosion is one of the most destructive processes in materials induced by environment. Protection and repair of metallic surfaces are major challenges in many engineering applications. We report a novel polyelectrolyte nanostructured coating incorporating the corrosion inhibitor, 8-hydroxyquinoline (8-HQ), into titanium dioxide (TiO2) nanoparticles (NPs). The potentiodynamic polarization measurements and real-time electrochemical impedance spectroscopy (EIS) monitoring demonstrated that the nanostructured coating protected aluminum (Al) from corrosion. Photocatalytic TiO2 was able to release incorporated 8-HQ only with the exposure to UV light resulting in a self-healing effect. Real-time EIS results showed that a new passivated layer was formed after 8-HQ molecules were released. The research in interfaces brings insights in understanding new aspects of corrosion and surface repair.

Mechanical properties and tribological behavior of a silica or/and alumina coating prepared by sol-gel route on stainless steel

The increasing importance of developments in the mechanical industry requires a constant evolution of skills, particularly in the area of functionalization and protection of metallic alloy surfaces. The wear of materials is one of the causes of loss of profitability. This study aims to develop solutions to extend the lifetime of stainless steel 304L. In this work, we have achieved to optimize protective coatings on stainless steel against wear, using sol-gel method associated with dip-coating technique. Three routes have been proposed to achieve this type of coating, a single sol precursor of silica or alumina and a mixture of sols precursors of both oxides. The results of tribological tests show that silica coating does not provide a performance gain towards the stainless steel protection. Alumina coating even as thin film is very efficient to resist against wear. Wear track widths on the sample is reduced by a factor 2, and the wear volume of the counterface is decreased by a factor 30, corresponding to a total wear volume reduction of a factor 7. The combination of both oxides seems to be a very promising way for such kind of application. With silica/alumina coating, we have obtained a reduction of widths wear track of a factor 1.5 and a decrease of friction coefficient as compared to alumina coating.

A new double-layer sol–gel coating to improve the corrosion resistance of a medical-grade stainless steel in a simulated body fluid

One of the effective ways to overcome some of the drawbacks of oxide coatings for corrosion protection of metal surfaces is the incorporation of an organic component into the inorganic network, although, commonly, film adhesion is disadvantageously affected. In this work, for the first time, by exploiting both inorganic and organic–inorganic coatings, a new double-layer thin film, which comprises ZrTiO4 as the bottom layer and ZrTiO4–PMMA as the top layer, was deposited on a medical-grade stainless steel substrate via a sol–gel spin coating method. According to potentiodynamic polarization experiments in a simulated body fluid, the substrate coated with this film exhibited superior corrosion resistance, compared with the same steel coated with purely inorganic ZrTiO4 and hybrid ZrTiO4–PMMA films. The superior corrosion resistance of the newly developed coating was found to be due to simultaneously the good adhesion of the lower, inorganic film and the low defect density of the upper, hybrid film.

A new method for surface modifications of carbon steels and alloys

A three-dimensional treatment method involving implantation of ions into solids immersed in a high voltage pulse discharge ignited on the left-hand-branch of the Paschen curve was elaborated about fifteen years ago. This method, named 3DII for short, has been used in the equipment JUPITER (Joint Universal Plasma and Ion Technologies Experimental Reactor) for practical purposes. Hereafter, the need for better means to improve the metal surface protection against aggressive media prompted an elaboration of the MOSMET concept which is based on a hybrid treatment involving the processes of implantation and deposition. It is significant that the processes can be set into action simultaneously or separately. In this article, the conditions of hybrid treatment of AISI SAE 1010, 1020 y 1045 carbon steels, their subsequent electrochemical diagnostics and corrosion test results are described. The corrosion rate of the samples treated by titanium hybrid discharge is found approximately an order of magnitude smaller as compared to the non-treated samples.

Atomic force microscopy–based study of self-healing coatings based on reversible polymer network systems

A self-healing polymer system is created by incorporating reversible covalent bonds into an epoxy–amine-based network structure. The self-healing concept is based on the reversible Diels–Alder reaction between furan and maleimide functional groups. The thermal and mechanical properties of the reversible network structure are tailored in order to achieve good self-healing properties for the corrosion protection of metal surfaces. Atomic force microscopy is proposed as a technique to study the self-healing behavior of coatings. Local thermal analysis techniques are used to study the local thermomechanical behavior of the reversible network. Nanosized defects in the coatings are made by means of nanolithography. The actual self-healing behavior is studied by atomic force microscopy imaging before and after the heating steps. The healing capability of elastomeric and glassy model systems is compared.

Silica doped with lanthanum sol–gel thin films for corrosion protection

We present here anticorrosive silica coatings doped with lanthanum ions for the protection of metallic surfaces as an alternative to chromate (VI)-based conversion coatings. The coatings were synthesized by the sol–gel method starting from silicon alkoxides and two different lanthanum precursors: La (III) acetate hydrate and La (III) isopropoxide. Artificial corrosion tests in acid and alkaline media showed their effectiveness for the corrosion protection of AA2024 aluminum alloy sheets for coating prepared with both precursors. The X-ray absorption Near Edge Structure and X-ray Absorption Fine Structure analysis of the coatings confirmed the key role of lanthanum in the structural properties of the coating determining its anticorrosive properties.

Nanoengineered Metal Surface Capsules: Construction of a Metal‐Protection System

Sonochemically formed metal capsules, which can protect a metal surface and release active compounds, are presented. The capsules are formed by modifying a metal surface into having a porous sponge layer; this layer is continuous with the bulk metal allowing for excellent adhesion. The porosity of the sponge layer and polyelectrolyte complexes allows active compounds to be stored and released depending on external stimuli. These porous capsules open up prospects in metal nanoengineering and surface protection as well as in encapsulation and polyelectrolyte applications.

Novel triazolyl bis-amino acid derivatives readily synthesized via click chemistry as potential corrosion inhibitors for mild steel in HCl

Triazolyl bis-amino acid derivatives readily synthesized via click chemistry were identified as novel potent corrosion inhibitors for mild steel in HCl. The inhibitive characteristic of compound 4 was studied in detail via gravimetric measurement, electrochemical impedance spectroscopy, potentiodynamic polarization and scanning electron microscopy. In addition, a quantum chemical study suggests that the triazole ring involved in these inhibitors is structurally essential for the protection of metal surface.

Corrosion protection of metal surfaces by atmospheric pressure plasma jet treatment

In this paper the corrosion protection of silicon-organic coatings applied by an atmospheric pressure plasma jet system was studied on copper (Cu) and aluminium (Al). The influence of a plasma pre-treatment on the defect density and the adhesion of the subsequently deposited plasmapolymer coating are presented. The quality of the coating was studied via visualization of defects by means of silver precipitation. Use of a reductive gas mixture for the plasma pre-treatment led to a significant reduction of the defect density. Additionally, the implementation of chromate-free corrosion inhibitors in the plasmapolymer layer enables an active corrosion protection of Al surfaces.