Thin Benzotriazole Films for Inhibition of Carbon Steel Corrosion in Neutral Electrolytes

Methods of Formation of Protective Inhibited Polymer Films on Tungsten

A comparative study of anticorrosive inhibited polymer films on the tungsten surface formed from an aqueous solution of inhibited formulations (INFOR) containing organosilane and corrosion inhibitors was carried out by means of the prolonged exposure of a tungsten product in a modifying solution and by the method of cataphoretic deposition (CPD). Depending on the method of forming films on tungsten, the molecular organization of the near-surface layers was studied (ATR-FTIR), and the subprimary structure of the films was explored (TEM). The optimal modes of cataphoresis deposition (CPD duration and current density applied to the sample) for the formation of a protective inhibited polymer film on the tungsten surface were established by means of SEM. The energy and thermochemical characteristics (sessile drop and DSC methods), as well as operational (adhesive behavior) and protective filming ability (EIS and corrosion behavior), according to the method of formation of inhibited polymer film, were determined. Based on the combined characteristics of the films obtained by the two methods and the deposition modes, the CPD method showed better performance than the electroless dipping method.

Application of Electrophoretic Deposition as an Advanced Technique of Inhibited Polymer Films Formation on Metals from Environmentally Safe Aqueous Solutions of Inhibited Formulations

The presented paper analyzes polymer films formed from aqueous solutions of organosilanes, corrosion inhibitors and their compositions. Methods of depositing inhibited films on metal samples, such as dipping and exposure of the sample in a modifying solution, as well as an alternative method, electrophoretic deposition (EPD), are discussed. Information is provided on the history of the EPD method, its essence, production process, areas of application of this technology, advantages over existing analogues, as well as its varieties. The article considers the promise of using the EPD method to form protective inhibited polymer films on metal surfaces from aqueous solutions of inhibitor formulations consisting of molecules of organosilanes and corrosion inhibitors.

Effect of Organosilicon Self-Assembled Polymeric Nanolayers Formed during Surface Modification by Compositions Based on Organosilanes on the Atmospheric Corrosion of Metals

Reducing the risks caused by losses due to the atmospheric corrosion of metal structures has been relevant for many years and is an important scientific and technical task. Previously, for this purpose, the preliminary modification of the surface of structural metals with solutions of compositions, based on both individual organosilanes and their mixtures with amine-containing corrosion inhibitors, was proposed. Such treatment leads to the formation of self-assembled siloxane polymeric/oligomeric nanoscale layers on the metal surface, which are capable of changing the physicochemical properties of the metal surface (namely, by reducing the tendency of the metal to corrosive destruction). In this work, annual atmospheric corrosion tests of samples of steel, copper, zinc, and aluminum without protection, and samples modified with compositions based on organosilanes in an urban atmosphere, were carried out. It was established (by the gravimetric method) that the corrosion rate of unmodified (without protection) metals is as follows: steel—0.0022 mm/year; aluminum—0.0015 mm/year; copper—0.00018 mm/year; and zinc—0.00023 mm/year. Using gravimetry and optical microscopy, it was shown that the preliminary modification of metal surfaces with compositions based on organosilanes led to the inhibition of both uniform and local corrosion of metals. The corrosion rates of samples that were modified with one-component compositions decreased by almost two times. The maximum inhibitory effect for the studied systems was demonstrated by mixed binary modifying compositions: mixtures of vinyl- and aminosilane, vinylsilane, and benzotriazole. The corrosion rate decreased for all the studied metals. The minimum effect was observed on zinc (2.5 times) and the maximum inhibition of the corrosion rate was obtained on copper (5.1 times). The mechanism of corrosion inhibition by layers formed as a result of surface modification with two-component mixtures was considered.

Thin Protective Coatings on Metals Formed by Organic Corrosion Inhibitors in Neutral Media

Protection of metals in neutral media with pH 5.0–9.0 (in humid atmospheres and various aqueous solutions) can be achieved by formation of thin coatings (up to several tens of nm) on their surfaces due to adsorption and more complex chemical interactions of organic corrosion inhibitors (OCIs) with the metal to be protected. The review contains three sections. The first section deals with coatings formed in aqueous solutions, while the second one, with those formed in organic and water-organic solvents. Here we consider metal protection by coatings mainly formed by the best-known classes of OCI (carboxylates, organophosphates and phosphonates) and estimation of its efficiency. The third section discusses the peculiarities of protection of metals in the vapor-gas phase, i.e., by volatile OCIs, and a relatively new type of metal protection against atmospheric corrosion by the so-called chamber inhibitors. OCIs with relatively low volatility under normal conditions can be used as chamber OCIs. To obtain a protective coating on the surfaces of metal items, they are placed in a chamber inside which an increased concentration of vapors of a chamber OCI is maintained by increasing the temperature. This review mainly focuses on the protection of iron, steels, copper and zinc.

An Overview on the Performance of 1,2,3-Triazole Derivatives as Corrosion Inhibitors for Metal Surfaces

This review accounts for the most recent and significant research results from the literature on the design and synthesis of 1,2,3-triazole compounds and their usefulness as molecular well-defined corrosion inhibitors for steels, copper, iron, aluminum, and their alloys in several aggressive media. Of particular interest are the 1,4-disubstituted 1,2,3-triazole derivatives prepared in a regioselective manner under copper-catalyzed azide-alkyne cycloaddition (CuAAC) click reactions. They are easily and straightforwardly prepared compounds, non-toxic, environmentally friendly, and stable products to the hydrolysis under acidic conditions. Moreover, they have shown a good efficiency as corrosion inhibitors for metals and their alloys in different acidic media. The inhibition efficiencies (IEs) are evaluated from electrochemical impedance spectroscopy (EIS) parameters with different concentrations and environmental conditions. Mechanistic aspects of the 1,2,3-triazoles mediated corrosion inhibition in metals and metal alloy materials are also overviewed.

Multilevel Self-Healing Characteristics of Smart Polymeric Composite Coatings

Smart polymeric composite coatings demonstrating multilevel self-healing characteristics were developed and characterized. The pH-responsive smart carriers were synthesized by loading halloysite nanotubes (HNTs) with the benzotriazole corrosion inhibitor (BTA) using the vacuum cycling method, referred to as (BTA-loaded HNTs). Similarly, mechanically triggered melamine urea-formaldehyde microcapsules encapsulated with the boiled linseed oil-self-healing agent (LO) denoted as (MUFMCs) having an average size of a ∼120 μm diameter with a wall thickness of ∼1.84 μm were synthesized by the in situ polymerization technique. The newly designed double-layered smart polymeric composite coatings (DLPCs) were developed by mixing 3 wt % BTA-loaded HNTs with epoxy and applying it on the clean steel substrate to form a primer layer. After its complete curing, a top layer of epoxy containing 5 wt % of MUFMCs was deposited on it. For an exact comparison, single-layer polymeric composite coatings (SLPCs) containing 3 wt % BTA-loaded HNTs were also developed. The Fourier transform infrared radiation spectra of MUFMCs and BTA-loaded HNTs indicate the existence of all desired functional groups, confirming the presence of loaded chemical species such as LO and BTA into the smart carriers. Thermogravimetric analysis (TGA) indicates that ∼18% BTA is successfully loaded into HNTs. Quantitative UV-spectroscopic analysis indicates a pH-responsive release of BTA from BTA-loaded HNTs, which is time-dependent, attaining its maximum value of ∼ 90% in an acidic medium after 30 h. Electrochemical impedance spectroscopy analysis conducted in 3.5 wt % NaCl solution at room temperature for different immersion times reveals that SLPC exhibits the maximum charge-transfer resistance (R_ct) of 55.47 GΩ cm² after the 7th day of immersion, and then, a declining trend is observed, reaching 26.6 GΩ cm² after the 9th day. However, in the case of DLPC, the R_ct values show a continuous increment, attaining a maximum value of 82.11 GΩ cm² after the 9th day of immersion. The improved performance of DLPC can be ascribed to the efficient triggering of the individual carriers in the isolated matrices, resulting in the release of LO and BTA to form individual protective films at the damaged area due to the oxidative polymerization process and triazoles' ability of passive film formation on the substrate, respectively. The tempting self-healing properties of DLPCs justify their decent role for long-term corrosion protection in many industrial applications.

Innovative Silver-Based Capping System for Mesoporous Silica Nanocarriers Able to Exploit a Twofold Anticorrosive Mechanism in Composite Polymer Coatings: Tailoring Benzotriazole Release and Capturing Chloride Ions

In this work, engineered stimuli-responsive mesoporous silica nanoparticles (MSNs) were developed and exploited in polymer coatings as multifunctional carriers of a typical corrosion inhibitor, benzotriazole (BTA). In detail, a new capping system based on a BTA-silver coordination complex, able to dissolve in acid and alkaline conditions and to simultaneously tailor the BTA release and the capture of chloride ions, was properly designed and realized. Acrylic coatings embedding the engineered MSNs were deposited onto iron rebar samples and tested for their protective capability in acid and alkaline environments. Results highlighted the high potential of the proposed system for the protection of metals, due to the synergistic effect of the mesoporous structure and the capping system, which guaranteed both the sequestration of chloride ions and the on-demand release of the effective amount of anticorrosive agents able to ensure the enhanced protection of the substrate.

Adsorption of Organosilanes on the Surface of Aluminium and the Formation of Organosilane Films to Protect It from Corrosion

Adsorption of diaminesilane (DAS), vinyltrimethoxysilane (VS) on the surface of thermally precipitated aluminium was examined. The use of different adsorption isotherms made it possible to calculate the adsorption heats for DAS and VS. It was determined that chemisorption of these organosilanes occurred on the surface of aluminium. Exposure of aluminium for 60 min to aqueous solutions of organosilanes led to the formation of organosilane films on the surface of the metal. The use of infrared spectroscopy and scanning electron microscopy in the work made it possible to assess the interactions of organosilanes with the metal surface, as well as to determine the structural features of the films and their thickness. Electrochemical and corrosion research methods made it possible to study the protective properties of organosilane films on aluminium.

Naproxen-Based Hydrazones as Effective Corrosion Inhibitors for Mild Steel in 1.0 M HCl

The corrosion-inhibiting performance of (E)-N’-(4-bromobenzylidene)-2-(6-methoxynaphthalen-2-yl) propanehydrazide (BPH) and (E)-N’-(4-(dimethylamino) benzylidene)-2-(6-methoxynaphthalen-2-yl) propanehydrazide (MPH) for mild steel (MS) in 1.0 M HCl was investigated using electrochemical methods, weight loss measurements, and scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscope (EDX) analysis. Raising the concentration of both inhibitors towards an optimal value of 5 × 10−3 M reduced the corrosion current density (icorr) and the corrosion rate of mild steel. The inhibitory effect of MPH, which showed the highest inhibition efficiency, was explored under a range of temperatures between 303 and 333 K. The inhibitory performance of both compounds significantly improved when the inhibitor concentration increased. The main result that flowed from potentiodynamic polarization (PDP) tests was that both compounds acted as mixed-type inhibitors, with a predominance cathodic effect. The adsorption of both compounds follows the Langmuir isotherm. SEM/EDX confirmed the excellent inhibition performance of tested compounds.