Corrosion Protection of Carbon Steel in Circulating Cooling Water by Open-chain Carboxyethyltin and Transition Metal Co-functionalized Tungstogermanates

Coke Quenching Plenum Equipment Corrosion and Its Dependents on the Quality of the Biochemically Treated Water of the Coke-Chemical Production

Steel corrosion processes that occur due to the effects of the biochemically treated water in coke quenching plenums have been studied. Model investigations into the processes of the corrosion failure of carbon St. 3 steel and alloyed 18Х1MF steel were carried out to study the behavior of the metal exposed to the action of the primary but treated water used for the coke quenching after the metal is heated to 373 K and 773 K. Different types of the corrosion that results from the contact of the carbon steel and alloy steel with the sodium hydroxide biochemically treated water of the coke-chemical production have been described. It was shown that the corrosion failure of the steels results from the formation of the films of hydrated iron oxides that appear in all the test media and these films show different behavior of adhesion to specimen surfaces. It was proved that the water treatment results in a certain decrease of the values of the mass and in-depth corrosion factors for St.3 and 12X1MF steels, however it fails to produce an essential effect when the steel is in constant touch with hot water.

Enhanced Corrosion Resistance of Carbon Steel in Hydrochloric Acid Solution by Polyoxometalate-Estertin Derivatives

The development of acid-resistant and efficient corrosion inhibitors is of great significance for metal protection in many industrial processes. In this work, eight cases of sandwich-type polyoxometalate (POM)-based inorganic-organic hybrids, namely, carboxyethyltin and transition metal (TM) cofunctionalized tungstoantimonates and tungstobismuthates, formulated as Na _x K_10-x [(SnR)₂(TM(H₂O)₃)₂(B-β-SbW₉O₃₃)₂]·mH₂O and Na _y K_10-y [(SnR)₂(TM(H₂O)₃)₂(B-β-BiW₉O₃₃)₂]·nH₂O (abbreviated as SbW₉-TM-SnR and BiW₉-TM-SnR; TM = Mn, Co, Ni, and Zn; m = 18, 24, 24, and 22; n = 30, 25, 20, and 21; SnR = Sn(CH₂CH₂COO)) are first used as green corrosion inhibitors for 20^# carbon steel in 0.5-2.0 M HCl solutions. Weight loss and electrochemical experiments prove that the corrosion inhibition efficiency is all above 81% for these POM-based corrosion inhibitors at 150 mg L^-1, and SbW₉-Mn-SnR shows the highest efficiency of 96.9% at 150 mg L^-1 after immersion in a 0.5 M HCl solution for 10 h. Scanning electron microscopy-energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy analyses show that these POM-based inhibitors form films on the carbon steel and the adsorption mechanism obeys the Langmuir adsorption model. The thermodynamic activation parameters were calculated, proving the occurrence of both chemical and physical adsorptions. The film-forming mechanism was also analyzed. This work provides guidance for synthesizing new lacunary POM-based materials to protect metals from corrosion in HCl pickling.

Synthesis, characterization and corrosion inhibition behavior of 2-aminofluorene bis-Schiff bases in circulating cooling water

Two new bis-Schiff bases, namely 2-bromoisophthalaldehyde-2-aminofluorene (M1) and glutaraldehyde 2-aminofluorene (M2) were synthesized and were characterized, the potentiodynamic polarization curve confirmed that they were anode type inhibitors.