EIS study on the corrosion behavior of rusted carbon steel in 3% NaCl solution

Abstract

Purpose -The purpose of this paper is to explore the long-term corrosion behavior of carbon steel in 3% NaCl solution and evaluate the effect of rust layer on the corrosion process. Design/methodology/approach -The corrosion behavior of rusted carbon steel in 3% NaCl solution was studied by means of infrared spectroscopy (IR) and electrochemical impedance spectroscopy (EIS). Findings -The results indicated that the corrosion of carbon steel was affected by chloride ion in initial immersion and then controlled by the rust layer. The rust layer consisted of a thin outer layer (g-FeOOH layer) and a thick inner layer (Fe 3 O 4 layer). The outer rust layer facilitated the cathodic process via reduction of g-FeOOH, while the inner rust layer provided a large cathode area and oxygen could be reduced on its surface. As a result, the corrosion rate of carbon steel was determined by the limiting diffusion rate of oxygen and stabilized at a high value. Originality/value -The corrosion model of rusted carbon steel in 3% NaCl solution was established. It is probable that the iron rust in all slightly acidic water with low alkalinity can promote the corrosion process via reduction of g-FeOOH. Anti-corrosion measures for iron in this type of solutions should be aimed to reduce the promoting effect of rust layer on the metal corrosion. The NaCl solution prepared from tap water is more suitable for the substitution of artificial water than that prepared from deionized water.

Influence of water salinity on corrosion risk—the case of the southern Baltic Sea coast

“…For instance, photosynthesis processes, which occur close to the water surface, increase oxygen concentrations (Ayers 1991; Rose et al 2003). Calcareous deposits (Zakowski et al 2013; Neville and Morizot 2002; Zamanzade et al 2007), deposition of corrosion products (Hu Jiayuan et al 2013; Jia-Yuan et al 2012; Liu et al 2013), water contamination (Melchers 2009; 2007) and fouling also affect corrosion rates (Khana et al 2013). …”

Optimizing the Required Cathodic Protection Current for Pre-Buried Pipelines Using Electrochemical Acceleration Methods

“…The electrons for the above reaction are provided by the oxidation of iron, which may be described as follows [ 16 ]: …”

“…Hence, −FeOOH accumulates on the surface of the metal and forms the early rust layer. The −FeOOH layer, which is in electrical contact with the metal, can be reduced according to [ 16 , 17 , 18 ]: …”

“…Fe 3 O 4 can accumulate at the interface between the −FeOOH and the surface metal, forming the inner rust layer. In previous works, it has been reported that ferrous ions and electrons can pass through Fe 3 O 4 , and hence the cathodic reaction can occur on the surface of the Fe 3 O 4 [ 16 , 19 ]. Additionally, the value of the oxygen diffusion coefficient ( D ) it has been proved that oxygen is reduced on the surface of the rust layer.…”

The corrosion behavior of Cu/Cr containing tube pile steel in half-immersion environment

“…It is well-known that the most effective and economical way in mitigating corrosion of steel is alloying the steel with less than 3 mass per cent amounts of elements such as Cr and Cu. This is due to the development of an adherent, protective rust layer formed on the steel (Misawa et al, 1974;Hu et al, 2013;Tamura, 2008;Xie et al, 2012;Wang et al, 2013).…”