Anti-corrosion Layer Research Articles

A study on the magnetically supported heteropolyacid nanophase catalysts

The magnetically supported heteropolyacid nanophase catalysts with the core-shell structure, in which the heteropolyacid molecules are embedded in the silica nanocoating supports, have successfully been obtained by a sol-gel incorporation technique rather than the impregnation method. The nanocomposites are composed of magnetic Fe 3O 4 nanophase cores, the interior silica nanocoatings as the anticorrosion layers and the exterior heteropolyacid-silica coatings. The catalytic performance of the resulted catalysts is comparable with that of pure heteropolyacids in esterification reaction of ethanol and acetic acid; in addition, the resulted catalysts can be used repeatedly without significant decrease of activity.

A design equation for evaluation of strain concentration factor in concrete coated X65 pipelines

An extensive parametric study using detailed nonlinear finite element (FE) models, was conducted in order to develop a design equation for predicting Strain Concentration Factor (SCF) in field joints of X65 concrete coated pipelines under bending. Dimensions of the pipeline and coating, material properties of the coating and anti corrosion layer, as well as the loading level, were included in the design equation. Buckingham's theorem was incorporated to simplify the equation by introducing non-dimensionalized parameters. The design equation was fitted to FE data using the nonlinear least square regression, while additionally, margins of safety were defined using the confidence interval concept for practical applications. The interactive effect of parameters on SCF was studied, leading to the introduction of a single non-dimensional “coating parameter” that can accurately describe the upper limit of the SCF. This study concluded with a definition of a critical “coating parameter” which can be used to assess safe combinations of coating thickness and installation loads, thus preventing excessive strain concentration.

Anticorrosive cerium-based coatings prepared by the sol–gel method

The development of efficient anti-corrosion and environmentally friendly coating systems are needed for the replacement of the highly toxic Cr-based conversion coatings for corrosion protection of aluminum alloys. In this study, we demonstrate that the direct application of ceramic cerium-based sol–gel coatings to AA7075-T6 substrates produces high-performance anti-corrosion layers. Electrochemical experiments and analyses of the microstructure demonstrate that the protective layers are very efficient for the passivation of the alloy surfaces operating as both passive and active barrier for corrosion protection.

Corrosion protection of galvanized sheet by maleic anhydride-g-liquid polybutadiene environmental friendly coatings

Maleic anhydride-g-liquid poly(1,2-butadiene) (MALPB) was modified with diethanolamine (DEA) to prepare anticorrosive coatings by using ethylene glycol monobutyl ether as non-volatile diluents which was considered environmental friendly; their curing processes and anticorrosive performances on galvanized sheet were studied. A robust coating could be obtained through the crosslinking reaction among hydroxyl groups and acids groups, as well as the crosslinking reaction of double bonds by adding peroxides including 0.25% benzoyl peroxide and 1% dicumyl peroxide (wt% of MALPB) as initiators. The Fourier transforming infrared (FTIR) spectra and differential thermo analysis (DTA) results showed that the coatings could be effectively cured at around 260 °C in 5 min. These coatings exhibited good flexibility and adherence on galvanized sheet while their adhesion decreased with the addition of pigments as observed by the digital microscope. As anticorrosive layers on galvanized sheet, these coatings provided effective barriers to electrolyte by impeding their contact with the metal surface; and their anticorrosive capability could be improved by the addition of pigments as observed through the DC polarization tests and salt spray tests.

Self-Healing Anticorrosion Coatings Based on pH-Sensitive Polyelectrolyte/Inhibitor Sandwichlike Nanostructures.

An anticorrosion layer of a smart polymer coating is developed. The nature and properties of the coating simultaneously provide three mechanisms of corrosion protection: passivation of the metal degradation by controlled release of an inhibitor, buffering of pH changes at the corrosive area by polyelectrolyte layers, and self-curing of the film defects due to the mobility of the polyelectrolyte constituents in the layer-by-layer assembly.

Deposition of Organosilicon-Based Anticorrosion Layers on Galvanized Steel by Atmospheric Pressure Dielectric Barrier Discharge Plasma

This work reports on organosilicon-based coatings deposited by atmospheric plasma processes on aluminium-zinc galvanization layers on steel in order to prevent corrosion. Hexamethyldisiloxane (HMDSO) is introduced as a precursor in an atmospheric pressure dielectric barrier discharge (DBD) plasma. Structure of the coating is evaluated by means of white light interferometry (WLI) and fourier transform infrared spectroscopy (FT-IR) measurements. Anti-corrosion properties are measured by means of electrochemistry testing and salt spray exposure. Admixtures of oxidizing gases in the plasma carrier gas enable faster deposition rate and more corrosion resistant organosilicon coatings.

Real-Time Monitoring of High-Temperature Corrosion in Stainless Steels by Open-Path Laser-Induced Plasma Spectrometry

Open-path laser-induced plasma spectrometry (OP-LIPS) represents an appealing alternative for the real-time monitoring of high-temperature processes due to its inherent non-invasive and remote capabilities. In this work, stainless steel samples have been analyzed at 10 meters from the laser source. The effect of the high-temperature conditions to the protective anti-corrosion layer have been analyzed, as well as additional factors such as the type of steel and the exposure time. The number of pulses required to ablate the alteration layer has been found to follow a linear relationship with the square root of the exposure time, in excellent agreement with the off-line thermogravimetric measurements described in the literature.

A process for welding structural steel elements coated with anticorrosive layers

A process for welding structural steel elements coated with anticorrosive layers

Surface activity of high-temperature perfluoropolyalkylether oil additives

Three additive materials for perfluoropolyalkylether-based high-temperature engine oils were studied, a bis-substituted dibenzothiazole, a diphenyl ether and a triphenyl phosphine. The focus of this work was to understand how the additives interacted with various surfaces to provide either anticorrosion or antiwear activity. In the case of the bis-substituted dibenzothiazole, the additive was found to form a thick, protective anticorrosion layer on the surface. The diphenyl ether served as another equally effective anticorrosion additive but failed to demonstrate surface activity. The third additive compound, triphenyl phosphine, was found to break down at the surface and form an inorganic polyphosphate which provided a level of both anticorrosion and antiwear function.

507842 Process for converting lead and lead oxides to barium metaplumbate

The present invention provides improved processes for forming anti-corrosion layers, particularly barium metaplumbate, on lead, lead alloy-, and lead oxide-containing substrates. The processes of the invention are used to form corrosion-resistant current collectors which are assembled into lead-acid batteries. The inventive methods used to form barium metaplumbate employ a salt solution which includes a barium compound and a solvent salt. In a first embodiment, a substrate material having at least a surface comprising elemental lead reacts with a salt solution to form barium metaplumbate. The salt solution includes a barium compound and an oxidizing agent. The solvent salt or barium compound may themselves be oxidizing agents, or an additional oxidant may be added to the solution. The molten salt solution is applied to the substrate in any known manner such as dipping, spraying, and brushing. Advantageously, a lead or lead alloy-containing substrate is dipped into a molten salt solution heated to a temperature at which a portion of the lead-containing substrate is directly converted to barium metaplumbate. In a further embodiment of the invention, barium metaplumbate is formed on a lead oxide-containing substrate. This process employs a salt solution comprising a barium compound and a solvent salt to convert lead oxide to barium metaplumbate.

Effect of plasma activation on the phase transformations of aluminum oxide

The deposition of protective, anticorrosive and wear resistant layers onto large-area metal substrates by physical vapor deposition techniques is gaining increasingly in industrial significance. This contribution deals with the deposition of aluminum oxide onto stainless steel. The aluminum oxide was deposited by reactive high-rate electron beam evaporation. Plasma activation of the vapor took place via a hollow-cathode plasma. The substrates were coated at a temperature of 500 and 700 °C and subsequently post-annealed in vacuo at 600, 800, 1000 and 1200 °C. At a substrate temperature of 500 °C with and without plasma activation, Al 2O 3 is deposited with different densities and amorphous to X-rays. At 700 °C without plasma activation, however, γ-Al 2O 3 is found in an amorphous matrix whereas plasma activation results in α-Al 2O 3 in an amorphous matrix. The effects of plasma activation and post-annealing temperature on the sequence of Al 2O 3 phase transformations were investigated. The hardness of the layers increases noticeably with plasma activation and post-annealing temperature. In addition, layers deposited under plasma activation exhibit better thermal stability with respect to volume contraction. Phase identification was done using X-ray diffraction, and transmission electron microscopy with selected area diffraction. The morphology of the layers was investigated by scanning electron microscopy and the hardness was measured by nanoindentation.

Effect of plasma activation on the phase transformations of aluminum oxide

The deposition of protective, anticorrosive and wear resistant layers onto large-area metal substrates by physical vapor deposition techniques is gaining increasingly in industrial significance. This contribution deals with the deposition of aluminum oxide onto stainless steel. The aluminum oxide was deposited by reactive high-rate electron beam evaporation. Plasma activation of the vapor took place via a hollow-cathode plasma. The substrates were coated at a temperature of 500 and 700 °C and subsequently post-annealed in vacuo at 600, 800, 1000 and 1200 °C. At a substrate temperature of 500 °C with and without plasma activation, Al 2 O 3 is deposited with different densities and amorphous to X-rays. At 700 °C without plasma activation, however, γ -Al 2 O 3 is found in an amorphous matrix whereas plasma activation results in α -Al 2 O 3 in an amorphous matrix. The effects of plasma activation and post-annealing temperature on the sequence of Al 2 O 3 phase transformations were investigated. The hardness of the layers increases noticeably with plasma activation and post-annealing temperature. In addition, layers deposited under plasma activation exhibit better thermal stability with respect to volume contraction. Phase identification was done using X-ray diffraction, and transmission electron microscopy with selected area diffraction. The morphology of the layers was investigated by scanning electron microscopy and the hardness was measured by nanoindentation.

Investigation of the pore-formation process during the chromizing of steel 40Kh by the circulation method

During the chromium plating of carbon steels, a carbide possessing elevated hardness and wear resistance is formed on the surface. It is known that the development of diffusion porosity, which is associated with the different diffusion mobilities of the atoms, is possible in the coatings. Use of carbides as an anti-corrosion protective layer requires its continuity; this is difficult to achieve by chromium plating in accordance with applicable regimes. In the literature, there are virtually no studies in which pore formation processes are addressed as applies to carbide coatings. This paper examines diffusion processes that take place in the surface layers of steel 40Kh during long-term annealing after chromium plating by the circulation method. The composition and properties of the chromium plated layer are studied. Possible mechanisms of pore formation and recommendations for the use of diffusion carbide coatings are proposed.

Development of a new detection method of partial discharge for EHV long‐distance active cable line

AbstractA new method was used to measure the characteristics of partial discharge (PD) for an active 9.5‐km long‐distance 275‐kV XLPE cable line with insulating joints. It was found that the detection of PD and the calibration of detection sensitivity were carried out safely and easily. The proposed method includes: detection of PDs and injection of calibration pulses using two pairs of metal electrodes placed on PVC jackets with anti‐corrosion layers separated by a joint sleeve sectionalizing insulator; measurement of detection sensitivity with distance using calibration pulses injected from an adjacent insulating joint; detection of PDs with a high S/N ratio measured at a frequency corresponding to the lowest noise level; and usage of rf cores attached at cross‐bonding leads and wires for sheath current limiters to reduce the crosstalk of signal and noise through these lines at insulating joints. Using a combination of these techniques, the highest detection sensitivity was 1 pC in the vicinity of an insulating joint, and 15 pC at 617 m from the adjacent joint. The sensitivity obtained by the conventional PD measurement using a low‐frequency method was at most 1000 pC.

The parameters of a discharge in an AT-1 biased activated reactive evaporation system for TiN deposition

The AT-1 system designed for deposition of hard coating, decorative or anticorrosive TiN layers with the biased activated reactive evaporation (BARE) method is described. The current-voltage characteristics of a plasma-activating electrode at various nitrogen pressures, electron beam currents (of the electron beam evaporator) as well as electrode geometries and positions are presented. The results of plasma measurements obtained by the glow discharge optical spectroscopy method are discussed.

The formation of an effective anti-corrosion film on copper surfaces from 2-mercaptobenzimidazole solution

The formation of an effective anti-corrosion film on copper surfaces has been achieved by immersion of a chemically cleaned copper plate into a solution of 2-mercaptobenzimidazole in ethanol. This film is extremely stable as compared with the anti-corrosion layer formed on an oxidized surface. The formation mechanism and the structure of the inert film have been investigated by the use of infrared and X-ray photoelectron spectroscopy. Its anti-corrosion characteristics in several media were investigated by the use of cyclic voltammetry.