Synergistic inhibition of polyethylene glycol and potassium chloride in water-based drilling fluids

Mud shale hydration and swelling are major challenges in the development of water-based drilling fuids(WBDFs).In this work,the inhibition performance and inhibition mechanism of polyethylene glycol(PEG)and potassium chloride(KCl)were investigated by hot rolling recovery tests,linear swell tests,Fourier transform infrared spectroscopy,X-ray difraction,atomic absorption spectrophotometry and X-ray photoelectron spectroscopy.The experimental results show that the combination of PEG and KCl achieved higher recovery and lower linear swelling rate than those obtained by individual PEG or KCl.Compared to the d-spacing of Na-montmorillonite(Na-Mt)with PEG or KCl,the d-spacing of Na-Mt with PEG+KCl was lower,which indicates that KCl and PEG have synergistic inhibition efect.This synergistic efect can replace sodium ions and water molecules from the interlayer space of Na-Mt and decrease the d-spacing of Na-Mt.Based on the above experimental results and analysis,a method for optimizing PEG and KCl concentrations was proposed and further verifed by rheological and hot rolling recovery tests of WBDFs.Hence,the results of this work can provide valuable theoretical guidance for developing other synergistic inhibitors.

THE SYNERGISTIC INHIBITION STUDIES OF SEVERAL AMINES AND CHLORIDE ION ON IRON IN THE ACIDIC PERCHLORIDE SOLUTIONS

The effect of chloride ion on the corrosion inhibition of iron caused by dencylamine(DA), dipentylamine(DDA) and dodecylamine(DPA) has been investigated by measuring the inhibitory coefficients for the anodic and cathodic processes at corrosion potential. It has been shown that the major synergistic inhibition effects between amines and chloride ions occur in the cathodic process, very weak in the anodic process. The anodic inhibition mechanism follows the competing adsorptive model, while the cathodic inhibition mechanism follows the cooperative adsorptive model.

Synergistic Inhibition Effect of Sodium Silicate and Acrylamide on the Corrosion of Carbon Steel in a High-concentration KCI Solution

The corrosion inhibition performances of sodium silicate（Na2SiO3） and acrylamide（AM） for Q235 carbon steel in a high-concentration KCl solution（25%, mass fraction） were investigated via static mass loss method, elec- trochemical measurements, scanning electron microscopy（SEM）, X-ray photoelectron spectroscopy（XPS） and Auger electron spectroscopy（AES）. AM shows poor inhibition performance, while Na2SiO3 exhibits a better inhibition per- formance. Moreover, the steel gains mass instead of losing mass in the presence of 0.5% Na2SiO3 and 0.5% AM, in- dicating that the corrosion is completely inhibited~ SEM analysis indicates that a compact protective film is formed on the steel surface by the combined use of inhibitors. Our results demonstrate that Na2SiO3 and AM could have a synergistic effect on steel corrosion in high concentrations of KCl. The synergistic inhibition mechanism is further conjectured by the XPS and AES analysis.

Corrosion resistance of tannic acid,d-limonene and nano-ZrO_(2)modified epoxy coatings in acid corrosion environments

The protection of rusted carbon steel in acid corrosion environments is of great significance for equipment to keep safe operation.In this work,we presented a method to protect the rusted steel by ru st conversion treatment and epoxy coating.Tannic acid was selected as rust conversion agent.Tannic acid,D-limonene and nano-ZrO_(2)were used to improve the corrosion resistance of epoxy coatings.The Raman spectra,Xray diffraction and 3 D confocal images were used to characterize the rust conversion reaction.Ad hesion test showed that the loss of wet adhesion of the optimal coating was relatively low due to the addition of tannic acid,limonene and nano-ZrO(2).The corrosion resistance of five different coatings was investigated by scanning electron microscopy(SEM)and electrochemical analysis.Results show that after 264 h acid immersion,the low frequency resistance of the optimal coating consisting of rust conversion treatment and additives is 10^(7)Ωcm^(2),three orders magnitude higher than that of the pristine coating.Moreover,SEM indicates that the optimal coating possesses a smooth surface and an unbroken interface between substrate and coating.Accordingly,the corrosion-resistant mechanism of the hybrid coating is proposed.