Protection of carbon steel against atmospheric corrosion by volatile inhibitors of IFKhAN series at high concentrations of CO2, H2S and NH3

Abstract

The protective efficacy of volatile inhibitors (VCI) of IFKhAN-A series (A-8, 112, 114, 118) against atmospheric corrosion of carbon steel St3 was studied at room temperature in air in the presence of corrosion stimulants (CS) at specified concentrations: CO 2 (0.2-0.6) vol.%, H 2 S (10-30) mg/m 3 and NH 3 (20-60) mg/m 3. The relative humidity was 100%. Corrosion tests were carried out in sealed containers of 7 liters in volume (desiccators) in two versions. In one version, only one CS was introduced into the air atmosphere. In the other, two or all three used CS were simultaneously injected into the gas phase. To create equilibrium concentrations of the CS in the air atmosphere, a special technique has been developed. The duration of the corrosion tests was 240-528 hours. Potentiodynamic polarization measurements were performed at a potential sweep rate of 0.66 mV/s immediately after immersing the electrodes in the solution and after 24 to 96 hours of their stay in the corrosive medium (in situ). In the presence of CO 2 in air atmosphere, the protective efficiency of all the VCIs studied is close to 100%. In the presence of NH 3 (20 mg/m 3), it is within 74% (IFKhAN-8) to 21% (IFKhAN-118). In the presence of H 2 S, the protective effect of the VCIs increases again, amounting to 93-97%. In uninhibited systems containing simultaneously two stimulants of corrosion, intense pitting is observed. When CO 2 and NH 3 are introduced simultaneously, the protective effect of the investigated VCIs is in the range of 76-87%, with CO 2 +H 2 S it is 81% (A-112 and 118) to 100% (A-114), and with H 2 S+NH 3 , it is 67-85%. The most effective is IFKhAN-114, which not only reduces the corrosion rate, but also eliminates pitting (CO 2 +NH 3). Introduction of IFKhAN-114 allows one to achieve the protective effect of 95% in the presence of all three CS simultaneously. The corrosion rate of steel in the uninhibited background solution is limited by the cathodic reaction. In the presence of (NH 4) 2 S as an NH 3 and H 2 S reaction

Inhibition of zinc corrosion by glycerol stearate in 1.0M hydrochloric acid medium with experimental, theoretical, and electrochemical techniques

“…The prevention occurs by immersing the metal inside the inhibition solution. 6 The metal absorbs the inhibitor on its surface, forming a protective film and preventing oxygen or water to attack. Furthermore, temperature has been identified as one of the factors affecting the rate of corrosion.…”

Suppression of local corrosion of steel, brass and copper with IFKhAN-114 volatile inhibitor

“…It was shown earlier in a number of works [1][2][3] that volatile corrosion inhibitors (VCI) of IFKhAN series efficiently suppress the atmospheric corrosion of steel [1][2][3], brass [3] and copper [3] under conditions of 100% relative humidity at the background and multiply increased concentrations of corrosion stimulants (CSs) NH 3 , H 2 S and CO 2 . Simultaneous presence of any two CSs reduces the effectiveness of some representatives of this series (IFKhAN-118 [2,3]) with respect to the rate of general corrosion and practically does not change that of other ones (IFKhAN-114 [2,3]). The presence of all three CSs increases the efficiency of VCI in a number of cases.…”

“…The presence of all three CSs increases the efficiency of VCI in a number of cases. However, the presence of all these corrosion stimulants separately or together, as a rule, causes significant local damage to the surface of metals [2,3]. Ulcers and numerous pits are formed on the surface of steel (St3), biphasic (α+β) brass and copper in 10-day tests.…”