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Purpose The purpose of this paper is to develop an equation for the synergistic corrosion of SRB and CO2 based on the D-W model. Design/methodology/approach The bacterial types in the a and ß pipelines were studied by the most probable number method, and the corrosion morphology of L360 in pipeline water samples was studied by surface analysis. The corrosion rate of L360 was studied using the weight loss method. The gray correlation method was used to calculate the degree of correlation between the influencing factors of corrosion under the synergistic effect of CO2 and SRB. The curve obtained from PIPESIM software and experiments data was then fitted using multiple non-linear regression method by MATLAB software. Findings The equation was used to predict the corrosion of the ß pipeline for verification, and it was found that seven out of ten excavation sites were within a 20% error range. Originality/value Using the gray correlation method, an equation that considers synergistic corrosion of SRB and CO2 has been developed based on the D-W model. The equation could be used to predict the corrosion rate of shale gas gathering pipelines through SRB and CO2 synergistic corrosion.

Hydrogen evolution reaction (HER) through water splitting depends on the development of efficient non-noble catalysts, among which the cobalt phosphide has been considered as one of the promising catalyst. Herein, the Gibbs free energy towards HER on CoP(110) surface was studied with density functional theory (DFT) calculation. It can be found that the crystal parameters calculated with both GGA-PBE and GGA-PW91 functionals consist well with the experimental result. The CoP(110) may possess good HER activity since it has good conductivity and appropriate Gibbs free energy (∆GH) for hydrogen adsorption.

In this study, experimental tests were performed to investigate the strain aging behavior of X100 pipeline steel in service and the resulting enhancement of susceptibility of pipelines to stress corrosion cracking (SCC). Results demonstrated that an immediate rise in temperature during coating application could result in strain aging of X100 steel, as indicated by increasing strength and decreasing elongation as well as the presence of Luders strain during yielding. The aged steel is associated with an enhanced cracking susceptibility under cathodic protection potentials. It is believed that strain aging is able to enhance hydrogen evolution and the further permeation into steel, resulting in hydrogen-induced SCC of the steel.

Weight-loss testing and computational fluid dynamic simulation were combined to investigate the essential roles of fluid mechanics and the sand impact in erosion-corrosion (E-C) of an X65 pipe steel in oil sands slurry. Results demonstrated that the steel E-C is resulted from the synergistic effect of the hydrodynamic shear stress and mechanical impact stress exerted on the steel surface. At low impact angles, such as 30°, the effect of shear stress is dominant. The particle impact stress becomes dominant when the impact angle increases to a high value, such as 90°. It is demonstrated that the maximum of E-C of the steel occurs at approximately 45° of the slurry impingement.

A series of InN thin films was grown on sapphire substrates via plasma-assisted molecular beam epitaxy (PA-MBE) with different nitrogen plasma power. Various characterization techniques, including Hall, photoluminescence, Raman scattering and Rutherford backscattering, have been employed to study these InN films. Good crystalline wurtzite structures have been identified for all PA-MBE grown InN films on sapphire substrate, which have narrower XRD wurtzite (0002) peaks, showed c-axis Raman scattering allowed longitudinal optical (LO) modes of A 1 and E 1 plus E 2 symmetry, and very weak backscattering forbidden transverse optical (TO) modes. The lower plasma power can lead to the lower carrier concentration, to have the InN film close to intrinsic material with the PL emission below 0.70 eV. With increasing the plasma power, high carrier concentration beyond 1 × 10 20 cm − 3 can be obtained, keeping good crystalline perfection. Rutherford backscattering confirmed most of InN films keeping stoichiometrical In/N ratios and only with higher plasma power of 400 W leaded to obvious surface effect and interdiffusion between the substrate and InN film.