Effect of pH on the Passivation of Carbon Steel by Sodium Borosilicate Controlled-Release Inhibitor in Simulated Recirculating Cooling Water

Abstract

A sodium borosilicate controlled-release inhibitor has been prepared via calcination for suppressing carbon steel corrosion in simulated recirculating cooling water (SRCW). The synthesized inhibitor was mainly composed of B2O3 and SiO2, coupling with small quantities of NaB5O6(OH)4·3H2O and NaB5O8·5H2O crystals. The total boron concentration gradually increased to 250 mg L–1 during the 28 days of release (2 g inhibitor in 500 mL SRCW) at 50 °C. A higher controlled-released rate existed in acidic environments (pH 5) than in neutral environments (pH 7) and alkaline environments (pH 9). The potentiodynamic polarization and electrochemical impedance spectroscopy results indicated that the inhibitor showed a better anticorrosion performance in neutral and alkaline environments than in acidic environments. In addition, a passive film with a Fe–O–B structure formed on the carbon steel surface to prevent the attack of the corrosive ions. A passivation-pitting-repassivation process was detected in the passive film by electrochemical noise, which demonstrated that the passive film exhibited a self-healing capacity. Moreover, a potential corrosion risk under the film was detected under the passive film in alkaline environment after 21 days of immersion. According to the experiment results and the analysis results of the point defect model, we believed that the anticorrosion performance of the sodium borosilicate inhibitor was in the following order: pH 7 > pH 9 > pH 5.

Amorphous Nickel–Iron Borophosphate for a Robust and Efficient Oxygen Evolution Reaction

“…[24] The B 1s spectra was fitted into two different peaks at 192.6 and 190.6 eV (Figure 2d), corresponding to the trigonal and tetragonal units of boron oxides, respectively. [25] Deconvoluted P 2p spectra exhibit two doublets (Figure 2e). The binding energies of P 2p 3/2 were located at 134 and 132.9 eV), which are associated with meta-phosphate (PO 3 − ) and phosphate (PO 4 3−…”

Passivation of Recirculating Open Water Cooling Systems Using New Organic Passivator

“…Passivation of Carbon Steel by Sodium Borosilicate in Simulated Recirculating Cooling Water was clarified by Jun Cui, Wenjio, Donghai yuan [15]. Passivation of carbon steel in neutral aqueous solution by dicarboxylic acid was investigated by G. Chan-Rosado and M.A.Pech -Canul they discovered that the passive layer consisted of inner oxide region and outer hydroxylated region [16].…”

Effect of buffer chemistries on the electrochemical corrosion behaviour of three metallic materials

“…There has been a greater interest to study the influence of pH in the occluded cells on the electrochemical behaviour of metals. To simplify the experimentation, smooth specimens were used and the pH was simulated using buffer solutions to study passivation [9], pitting [10], crevice [11], and stress corrosion cracking [12].…”