Purpose The purpose of this study is to elucidate the effects of electric-arc-induced ablation on the corrosion behavior of pipeline steel in neutral and high pH environments. Design/methodology/approach Electrochemical testing, an atmospheric-pressure immersion experiment and various techniques (e.g. scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy) were used to examine the effects of electric-arc-induced ablation on the corrosion behavior of pipeline steel in neutral and high pH environment. Findings Electric-arc-induced ablation occurred preferentially in areas of inclusion. The corrosion resistance of an ablation pit was lower than that of non-ablation areas. In the neutral soil solution, general corrosion was the dominant corrosion that affected pipeline steel; the effect of ablation was small but pitting corrosion could still be induced. In a high pH environment, the samples without ablation were passivated, whereas the samples with ablation pits could not be passivated; the ablation pits were likely to develop pitting corrosion. Originality/value Electric-arc-induced ablation can reduce the corrosion resistance of pipeline steel under high-voltage direct current interference.

PurposeSulfate-reducing bacteria (SRB) are recognized by scholars as the most important class of bacteria leading to corrosion of metal materials. It is important to use the properties of microorganisms to inhibit the growth of SRB in the corrosion protection of metal materials and to protect the environment.Design/methodology/approachIn this work, the behavior of anaerobic Thiobacillus denitrificans (TDN) intracellular enzyme inhibition of SRB corrosion of EH36 steel was investigated with electrochemical impedance spectroscopy, biological detection technology and X-ray photoelectron spectroscopy.FindingsResults showed that the SRB crude intracellular enzyme affected the corrosion behavior of EH36 steel greatly and the purified TDN intracellular enzyme inhibits SRB intracellular enzyme corrosion to EH36 steel.Originality/valueA perfect enzyme activity inhibition mechanism will provide theoretical guidance for the selection and application of anticorrosion microorganisms, which is of scientific significance in the field of microbial anticorrosion research.

PurposeThis paper aims to research the effect of different concentrations for Nd(NO3)3 and Ce(NO3)3 on the microstructures and corrosion resistance of Ni-W-P composite coatings through electroless plating method.Design/methodology/approachScanning electron microscope, attached energy dispersive spectroscopy system and X-ray diffraction were used in this work. Meanwhile, the immersion test and electrochemical tests were used to characterize the corrosion behavior of the coating.FindingsThe coatings prepared at 1.00 g·L−1 Nd(NO3)3 exhibit a dense structure and high phosphorus content (12.38 wt.%). In addition, compared to the addition of Ce(NO3)3, when Nd(NO3)3 was introduced at a concentration of 1.00 g·L−1, the minimum corrosion rate of the coating was 1.209 g·m−2·h−1, with a noble Ecorr (−0.29 V) and lower Icorr (8.29 × 10−4 A·cm−2).Originality/valueThe effects of rare earths on the deposition and corrosion resistance mechanisms of Ni-W-P composite coatings were explored, with the rare earth elements promoting the deposition of nickel and tungsten atoms. Simultaneously, the amorphization of the coating increases, which excellently enhances the corrosion resistance of the coating.

PurposeThis study aims to provide a model to predict the service life of a thick organic coating.Design/methodology/approachA series of thin coating films are rapidly tested under the same exposure condition as the thick coating in its service condition by means of electrochemical impedance spectroscopy, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction.FindingsThe validity of the model is successfully verified. The long-term protectiveness or service life of a thick organic coating can be rapidly predicted.Originality/valueThe prediction model does not require long-term experiments or any test that may alter the degradation mechanism of the thick coating.

PurposeN-containing heterocyclic benzotriazole derivatives as new corrosion inhibitor for mild steel contained in emulsion were synthesized, and their inhibition behaviors for mild steel (MS) contained in emulsion were investigated by experiments and theoretical calculations, and this study aims to prove that two new inhibitors have excellent inhibition efficiency for steel corrosion.Design/methodology/approach2-(1H-benzo[d][1,2,3]triazol-1-yl)-N,N-dioctylacetamide (BTN) and O-(3-(1H-benzo[d] [1,2,3]triazol-1-yl)propyl) S-(2-(dioctylamino)-2-oxoethyl) carbonodithioate (BTSC) as a new corrosion inhibitor were synthesized, and their inhibition behaviors for MS contained in emulsion were investigated by gravimetric experiment, electrochemical tests and theoretical calculations.FindingsResults of gravimetric experiment, electrochemical tests show that BTSC exhibit excellent inhibition performance, and it has a higher inhibition efficiency of 96.6% than that BTN. The resultant adsorption films from BTN/BTSC adsorbed on MS, effectively inhibiting the corrosion of MS is mainly through chemisorption and follow to Langmuir’s adsorption isotherm.Originality/valueExperimental and theoretical calculations display that two new synthesized inhibitors are excellent corrosion inhibitor for MS contained in emulsion. Electrons of inhibitors mainly focus on the C, N, S and O atoms, which demonstrate these atoms are the centers of negative charge, and they supply electrons to Fe atoms through coordination bonds.

PurposeThe purpose of this study is to prepare copper oxide nanoparticles (CuO NPs) in an easy and efficient way using a natural and environmentally friendly substance like ascorbic acid. Various concentrations of these nanoparticles were then added to solvent-free coating formulations to produce highly hydrophobic, corrosion-resistant and antimicrobial hybrid coatings. These hybrid formulations were also used to coat the spent fuel casks for their integrity.Design/methodology/approachThe hybrid coated films were then characterized by X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), water contact angle and Scanning electron microscope (SEM). In addition, different measurements, namely, mechanical, physical, chemical, thermal, corrosion tests, open circuit potential and antimicrobial activity of these hybrid films were performed.FindingsThe results showed that the copper oxide was prepared at nanometer scales with good homogeneity and diffusion in the epoxy acrylate matrix. It also showed that some hybrid coatings have high corrosion resistance, strong hardness, excellent water resistance, remarkable antimicrobial activity and high thermal stability compared to virgin epoxy acrylates.Originality/valueThe formula containing 0.5% CuO NPs was found to provide the highest corrosion protection and antimicrobial activity for mild steel in 3.5% sodium chloride (NaCl).

PurposeThis paper aims to analyze the high temperature (200°C) corrosion behavior of 2205 duplex stainless steel in acidizing stimulation solution containing hydrochloric acid (HCl) and acetic acid.Design/methodology/approachThe corrosion rate of 2205 duplex stainless steel in all kinds of acid solutions was calculated through immersion tests and electrochemical test. The corrosion product composition is analyzed by X-ray diffraction analysis. The element composition and element distribution before and after corrosion were analyzed by an X-ray energy spectrometer. The corrosion morphology of the steel surface was observed by a scanning electron microscope. Both static and dynamic corrosion experiments were carried out at 200°C.FindingsThe results show that 2205 duplex stainless steel has excellent corrosion resistance in low to high concentration acetic acid solutions, but increasing the concentration of Cl− in acetic acid solution will accelerate the corrosion rate. Low concentration HCl solution can cause serious corrosion to 2205 duplex stainless steel. The system of HCl and acetic acid will produce a synergistic effect on corrosion of 2205 duplex stainless steel and accelerate the corrosion. Sb2O3 is a good corrosion inhibitor synergist for high-temperature acidizing stimulation solution.Originality/valueThe amount of HCl that is used in acidizing stimulation is usually determined by the dissolution effect of the acid on the rocks, but for ultra-high-temperature reservoirs, the amount of HCl should be based on reducing the corrosion of oil and gas wells.

PurposeThis paper aims to investigate the electrochemical corrosion rate of galvanized steel wires for bridge cables.Design/methodology/approachThe electrochemical corrosion test and response surface analysis of galvanized steel wires were carried out, and the variety of polarization curves of galvanized steel wires under different corrosion parameters was discussed. The expression of corrosion rate of galvanized steel wires under the action of single and multi-factor coupling was established.FindingsThe polarization curves of galvanized steel wires under different Cl- concentrations, pH value and temperature were basically similar, but all show different degrees of deviation and some anodic polarization curves had inflection points. For example, when the Cl- concentration reached 3.5%, the corrosion rate of galvanized steel wire was four times that of pure water.Originality/valueThe influence relationship of single and multi-factor coupling on the corrosion rate of galvanized steel wires was as follows: RCl > RT * Cl > RT > RpH > RpH * T > RpH * Cl.

PurposeLightweight, durable and economical materials production has gained considerable importance according to the needs of developing technology. The purpose of this paper is to develop an new aluminum alloy by powder metalurgy.Design/methodology/approachPowder metallurgy, which provides controllably on desired end product, method was applied. Aluminum alloy was created with Al, Zn, Mg, Cu powders and 1.5% Na2[B4O5(OH)4].8H2O added. It was pressed under high pressure and sintered at 600 °C under N2 gas atmosphere. Density, hardness behaviors and thermal properties were determined. Surfaces and crystal structures of samples were characterized.FindingsThe addition of borax made easier grains coming to together, acting as binders and the AlB2 crystal phase was formed. It was also observed that MgZn2, Al2CuMg phases were formed. In this way, the pores between the particles of the material were reduced from 35% to 5% total porosity and the hardness of the material was increased 29 N/mm2 to 45 N/mm2 (Brinell Hardness, HB). The surface properties improved and the hydrophobicity of the surface (from 63° to 102° contact angle with borax) increased. Thus, the heat transfer among atoms get easier and the borax addition decreased specific heat capacity and enthalpy of aluminum–borax samples. This situation was also simulated with the heat transfer module of COMSOL. As result, the energy required reduced. In the other word, sintering process occurred at low temperature and more efficient.Originality/valueNew aluminum alloy has been created from different amounts of Zn, Mg, Cu elemental powders. In addition to literature, relationship of borax and aluminum and other alloying elements on the mechanical, thermophysical and surface properties of new obtained aluminum alloy has been investigated.

PurposeThe purpose of this paper is to study systematically the corrosion behavior of AZ31 magnesium (Mg) alloy with different concentrations of bovine serum albumin (BSA) (0, 0.5, 1.0, 1.5, 2.0 and 5.0 g/L).Design/methodology/approachElectrochemical impedance spectroscopy and potential dynamic polarization tests were performed to obtain corrosion parameters. Scanning electrochemical microscopy (SECM) was used to analyze the local electrochemical activity of the surface film. Atomic force microscope (AFM), Scanning electron microscope-Energy dispersive spectrometer and Fourier transform infrared spectroscopy were used to determine the surface morphology and chemical composition of the surface film.FindingsExperimental results showed the presence of BSA in a certain concentration range (0 to 2.0 g/L) has a greater inhibitory effect on the corrosion of AZ31, however, the presence of high-concentration BSA (5.0 g/L) would sharply reduce the corrosion resistance.Originality/valueWhen the concentration of BSA is less than 2.0 g/L, the corrosion resistance of AZ31 enhances with the concentration. The adsorption BSA layer will come into being a physical barrier to inhibit the corrosion process. However, high-concentration BSA (5.0 g/L) will chelate with dissolved metal ions (such as Mg and Ni) to form soluble complexes, which increases the roughness of the surface and accelerates the corrosion process.