On penetration of the migrating corrosion inhibitor IFKhAN-80 into cement stone

The physicochemical features of corrosion inhibition of metals (alloys) strongly depend on the composition of the corrosive environment, its pH, temperature t, hydrodynamic conditions, the chemical nature of the metal to be protected, and the state of its surface, the presence of oxides, dirt, or corrosion products on it. This "multifactor" nature of corrosion seriously complicates the theoretical choice of an efficient corrosion inhibitor (CI), often requiring careful experimental studies and creating unjustified skepticism about the fundamental character of the physical chemistry area related to the study and development of CIs. Meanwhile, this skepticism can be proved wrong by the progress made over the past quarter century in various subareas. Key words: corrosion inhibitors, adsorption, metal passivation, volatile corrosion inhibitors, migrating inhibitors, local depassivation of metals, protecting coatings. Adsorption of corrosion inhibitors on metals and passivationAdsorption on a protected surface is the first event that often determines CI efficiency. Difficulties of its measurement in situ are caused by dissolution and/or oxidation of the metal substrate with time. The uncertainty in separating the effects of adsorption and changes of the state of the metal surface often does not permit to unambiguously interpret the results obtained, for example, by electrochemical impedance spectroscopy (EIS) or using radioactive tracers. In his first "Inhibitors of corrosion of metals in neutral media" (1953), I.L. Rozenfel'd considered only inorganic CIs. He remained interested in these inhibitors throughout his whole life, so it is not surprising that in his latest book "Corrosion Inhibitors" (1977) he reexamined the interaction of some inorganic CIs, primarily chromate, with the metal at a more modern level, including a quantum-chemical approach. However, studies on the

Section: Goal-oriented Corrosion Inhibitorsmentioning

confidence: 99%

Progress in the science of corrosion inhibitors

Kuznetsov

pr.²,

Moscow³

et al. 2015

“…Concrete carbonation is a slow process, and depassivation sites (pits) appear on the reinforcement by the above mechanism for a long time after reinforced concrete structures have been put into service. However, the results published previously [3,4] give a reason to believe that reinforcement can undergo pitting even during concrete curing when the pore liquid has not yet become sufficiently alkaline for passivation. The resulting pits may serve as mechanical stress points and concrete delamination sites, thus weakening reinforced concrete structures considerably.…”

Section: Introductionmentioning

confidence: 99%

“…The latter has been developed at the Institute of Physical Chemistry of the Russian Academy of Sciences and is positioned as a versatile (contact and migrating) corrosion inhibitor for concrete reinforcing steel [3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Corrosion and electrochemical behavior of steel in hardening concrete

2017

It has been shown using corrosion and electrochemical methods that reinforcing steel is subject to pitting during the initial period of concrete hardening. It is intensified if chlorides are present in the tempering water and/or if corrosion products exist on the metal surface. IFKhAN-80 inhibitor added with tempering water hinders pit formation on steel during concrete hardening, up to complete suppression of this process. Even at high chloride concentrations and in the presence of corrosion products on the metal surface, reinforcing steel in concrete is passivated some time after concrete tempering.

“…Non commercial inhibitors, both inorganic and organic have been studied: both inorganic (zinc oxide, molybdates, borates, stannates) and organic compounds (benzoate and its derivatives, carboxylate ions, quaternary ammonium salts, citrate and amine-based substances) [11,[33][34][35][36][37][38][39].…”

Section: Introductionmentioning

confidence: 99%

Experiences on corrosion inhibitors for reinforced concrete

Bolzoni¹,

Brenna²,

Fumagalli³

et al. 2014

Corrosion of carbon steel reinforcement is the most important cause of premature failure on reinforced concrete structures. Prevention of corrosion is primarily achieved in the design phase by using high quality concrete and adequate cover. Additional prevention methods are adopted when severe environmental conditions occur or on structures requiring very long service life. Among these methods, corrosion inhibitors seem to offer a simple and cost effective prevention technique. They may be used both as a preventative techniques, if added to fresh concrete, and as a repair system, if applied on hardened concrete.The performance of corrosion inhibitors for reinforced concrete structures affected by chloride induced and carbonation corrosion has been studied at PoliLaPP, Laboratory of Corrosion of materials "P. Pedeferri" of the Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano, in the last 15 years.Organic commercial admixed corrosion inhibitors delayed the occurrence of chloride induced corrosion. This result is related to two effects: reduction of the rate of chloride transport into concrete and increase of the critical chloride threshold.Commercial migrating corrosion inhibitors (MCI) are able to delay time-to-corrosion of passive rebars in concrete subjected to chlorides ponding; this effect is mainly related to the reduction of chlorides diffusion coefficient. MCI can reduce the corrosion rate after corrosion initiation only in carbonated concrete, nevertheless efficiency is low and residual corrosion rate is not negligible.Commercial MCI can penetrate into concrete mainly through capillary sorption but penetration depth is limited to 20 mm.The results obtained with nitrite-based inhibitor confirm literature data: the inhibitor is effective if the molar ratio is higher than 0.5-0.6; in carbonated concrete, due to insufficient amount of inhibitor, no significant effect has been observed on corrosion rate.Among the tested organic substances, compounds containing carboxylic group showed the best results solution tests: pitting potential, time-to-corrosion and critical chloride content are similar to those obtained with sodium nitrite. In concrete tests, only one amine and one amino acid showed good performance increasing the critical chlorides Int. J. Corros. Scale Inhib., 2014, 3, no. 4, 254-278 255 threshold with respect to the reference condition. For carboxylate substances, a strong link was found between inhibiting properties and molecular structure.