Corrosion Resistance In Aqueous Media Research Articles

Corrosion barrier alumina/zirconia bilayer stack on low Cr steel by direct liquid injection metalorganic chemical vapor deposition

Numerous industrial fields necessitate the development of advanced metallic materials presenting high corrosion resistance in aqueous media and being less expensive than classical high chromium steels. In the present work, amorphous zirconia, alumina and alumina/zirconia coatings have been deposited on 2 wt% chromium steel coupons using an innovative direct liquid injection metal organic chemical vapor deposition process. Scanning electron microscopy and X-ray diffraction reveal that the alumina sublayer acts as an efficient barrier against steel oxidation occurring during the amorphous zirconia deposition performed under O2 at 400 °C. They also show that the steel oxidation occurring concomitantly to the zirconia coating modifies the film morphology by increasing its roughness and thickness, in comparison with the same zirconia coating on alumina. The anticorrosive properties of the thin films have been studied by an immersion test of the bare and coated coupons in deionized water at 80 °C during 6 days and by electrochemical impedance spectroscopy in aqueous sodium chloride solution for 48 h. They reveal that, in contrast to alumina and zirconia monolayers alone, the alumina/zirconia stack acts as a corrosion protection coating in pure water through a synergetic barrier effect against (i) oxidation by alumina and (ii) aqueous corrosion by zirconia.

Establishment of optimal technological regimes of out-of-furnace processing of low-alloyed steels in order to ensure their high corrosion resistance in aqueous media through the formation of favorable non-metallic inclusions

Based on the analysis of the technological principles of managing the formation of nonmetallic inclusions and the results of additional studies, optimal process conditions for out-of-furnace processing of steel were established, ensuring not only low contamination of nonmetallic inclusions (HB), but also the formation of nonmetallic inclusions of a favorable morphology that do not adversely affect the corrosion resistance of steel. It is shown that this is achieved by regulated input of aluminum for deoxidation and alloying of steel, limiting its content in steel, limiting the input temperature of aluminum and calcium at the final processing stage, as well as the duration of the flushing period. For steel, micro-alloyed with titanium, it is also possible to form another type of HB, which also do not adversely affect the corrosion resistance of steel. The oxide component of such HB with a high content of calcium and titanium acquires a rounded shape. The formation of such HB is achieved by the regulated input of aluminum, titanium and calcium at the final stage of processing.

Establishment of Optimum Production Regimes for Extra-Furnace Processing of Low-Alloy Steels in Order to Ensure their Good Corrosion Resistance in Aqueous Media through Formation of Favorable Non-Metallic Inclusions

Optimum production regimes are established for steel extra-furnace treatment providing not only low contamination with non-metallic inclusions (NI), but also formation of NI with favorable morphology not having a deleterious effect on steel corrosion resistance. It is shown that this is achieved by controlled input of Al in steel alloying and deoxidation stages, limiting its content in steel, limiting the temperature for additionof aluminum and calcium in the final treatment stage, and also the duration of the flushing period. For steel micro- alloyed with titanium it is also possible to form another type of NI that does not adversely affect steel corrosion resistance. The oxide component of these NI with a high content of calcium and titanium acquires a rounded shape. Formation of such NI is achieved by the controlled addition of Al, Ti, and Ca in the concluding treatment stage.

Technological Principles of Controlling the Formation of Non-Metallic Inclusions in Carbon and Low Alloy Steels to Increase their Corrosion Resistance in Aqueous Media

The analysis of literature data on the technological principles of controlling the formation of non-metallic inclusions in carbon and low alloy steels to increase their corrosion resistance in aqueous media is carried out. The key technological parameters of steel treatment in the ladle are summarized that ensure not only low contamination of steel with non-metallic inclusions, but also the formation of non-metallic inclusions of favorable morphology.

Technological principles of controlling the formation of non-metallic inclusions in carbon and low alloy steels to increase their corrosion resistance in aqueous media

Technological principles of controlling the formation of non-metallic inclusions in carbon and low alloy steels to increase their corrosion resistance in aqueous media

Effect of Heat Treatment on Corrosion Activity of Nonmetallic Inclusions and Steel Corrosion Resistance in Aqueous Media

Results of the studying the effect of heat treatment on the corrosion activity of non-metallic inclusions in contemporary steels, and correspondingly on corrosion resistance of the steels themselves, as applied to the conditions of oil-field pipeline operation, are presented. It is shown that after heat treatment (quenching and tempering) steel contamination with nonmetallic inclusions detected by Oberhoffer reagent and affecting steel corrosion resistance decreases (some nonmetallic inclusions lose their corrosive activity), which ensures an increase in corrosion resistance of steel (obtaining lower values saturation current density when tested by an electrochemical method for assessing corrosion resistance).

Effect of Chemical Composition and Microstructure Parameters on Carbon and Low-Alloy Steel Corrosion Resistance

An improvement in resistance to overall and local corrosion in neutral aqueous media with hydrogen index pH 6–8 is important for numerous structures operating under atmospheric conditions, in sea water, for heating network pipelines, oil industry pipelines (oil pipelines and water conduits), and many other forms of structure and equipment. Under these conditions, corrosion proceeds by a classical electrochemical mechanism. Today, there is no single point of view for the optimum chemical composition and microstructure for steels for simultaneous provision of good corrosion resistance in aqueous media and satisfactory mechanical properties. In this work, the effect of chemical composition and microstructure parameters on corrosion resistance of carbon and low-alloy steels of strength classes K52–K60 in aqueous media is studied with the aim of developing specifications for these properties in order to increase the operating life of steel equipment, in particular oil industry pipelines.

Increase in Corrosion Resistance in Aqueous Media of Low-Alloy Steel Used as the Main Layer of Corrosion-Resistant Bimetals

The article is devoted to a study of corrosion resistance of low-alloy steels, in relation to chemical composition, heat treatment conditions, other steel properties, and heat treatment regimes. The effect of chemical composition, degree of deoxidation, and steel cleanliness with respect to nonmetallic inclusions on steel corrosion resistance is demonstrated, including those that may be used as a main layer in corrosion-resistant bimetals.

Study of the Effect of Chemical Composition and Heat Treatment on Corrosion Resistance Indices for Martensitic Class Stainless Steels Alloyed with Nitrogen

Corrosion tests are performed on developed chromium corrosion-resistant steels alloyed with nitrogen. A set of tests shows that depending on chemical composition and production parameters the corrosion resistance indices for steels of one class may differ by an order of magnitude. Revelation of a dependence makes it possible to conclude that an increase within steel of nitrogen and molybdenum content combined with quenching and low-temperature tempering at 400°C makes it possible to prepare steel with good pitting corrosion resistance in aqueous media, particularly, under sea water conditions.

The Corrosion Attack on Stainless Steel 316L and WC-Co in High Sulphate-Chloride Ratio

Austenitic stainless steels and cermets alloy has been used extensively in many sectors due to their highly resistance to corrosion attack and excel in mechanical properties. However, in corrosive media both materials are susceptible to corrosion attack especially in seawater and high temperature. Cermet alloys are a combination of ceramic and metal. Therefore, cermets exist in high corrosion resistance in aqueous media and the corrosion rate is complex to identify. This paper presents the corrosion mechanism of 316L and cermets alloy exposed to high concentration of sulphate in the salinity of seawater. The solution (media) was prepared according to the same composition as seawater including pH, salinity and dissolved oxygen. The corrosion mechanism were characterized to breakdown potential (Eb) of 316L which are the potential once reaches a sufficiently positive value and also known as pitting potential. This is the most point where localized corrosion susceptibility to evaluate and considered a potential, which could be an appropriate point according to any given combination of material/ambient/testing methods. The Eb value of 316L in high sulphate are higher compared to seawater in every temperature which elucidate that some anions accelerate corrosion attack whereas some anions such as sulphate behaves as inhibiting effect to 316L.

Corrosion Behavior of WC-Co in High Sulphate Content

Cermet alloys are a combination of ceramic and metal. Therefore, cermets exist in high corrosion resistance in aqueous media. However, because of the nature of cermet alloys, which have a metal and ceramic composition, the corrosion rate is complex to identify. The corrosion attack could be assessed by calculating the corrosion rate or through electrochemistry evaluation. Generally, the corrosiveness of media increased as the anions contents increased. This paper presents the corrosion mechanism of cobalt tungsten-carbide (WC-Co) exposed to a high concentration of sulphate in the salinity of seawater. The solution (media) was prepared according to the same composition as seawater including pH, salinity and dissolved oxygen. The corrosion rate was then identified and the corrosion mechanism revealed. The corrosion rate was identified at 4°C, 20°C, 50°C and 80°C and compared with the corrosion rate of WC-Co in seawater. The results revealed that sulphate has an inhibiting effect that minimises the corrosion attack on WC-Co. The corrosion rate decreased as the sulphate content in seawater increased, and an increase in the temperature increased the corrosion attack on WC-Co.

On the Corrosion Resistance in Aqueous Media of Ball-milled Magnesium

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