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The purpose of this paper is to study the effects of Cl⁻ and direct stray current on the soil corrosion of three grounding grid materials.

The electrochemical corrosion properties of three grounding grid materials, which include the Q235 steel, Q235 galvanized flat steel and copper, were measured by means of the weak polarization curve method and electrochemical impedance spectroscopy; the corrosion rate of specimens was calculated using the weight loss method; and the specimen surfaces were characterized using the scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction analysis.

Results showed that both factors, Cl⁻ and direct stray current, can accelerate the corrosion rate of grounding grid materials. The magnitude of DC stray current density affected the mass transfer type and response frequency of the anode and cathode reaction of grounding materials, while the Cl⁻ contents of the soil only affect the mass transfer rate of the electrode material from the electrochemical impedance spectroscopy diagrams. The electric field generated by the DC stray current caused Cl⁻ directed migration. The larger the DC stray current density, the greater the diffusion process and the greater the weight loss rate of the grounding grid materials that would have a logarithmic relationship with the Cl⁻ content at the same DC stray current density. The corrosion resistance of the three materials is copper > Q235 galvanized flat steel > Q235 flat steel.

The paper provides information regarding the relationship among Cl⁻, direct stray current and corrosion of three grounding grid materials by means of electrochemical impedance spectroscopy. Meanwhile the weight loss rate is the logarithmic relationship with the Cl⁻ content, which is useful for understanding the corrosion mechanism of Q235 steel, Q235 galvanized flat steel and copper under the condition of Cl⁻ and direct stray current in soil.

Reliable grounding is an important condition for the stable operation of substations and cathodic protection is one of the electrochemical protection technologies for substation grounding grids. The purpose of this paper is to consider the design proposal, installation, construction requirements and monitoring methods for Hunan 220 kV substation grounding grid.

This paper treated Hunan 220 kV substation grounding grid as a research object. The physical and chemical data of three soil samples were measured, German DIN50929 evaluation criteria were used to assess its corrosion and a sacrificial anode cathodic protection design was selected, based on advanced concepts.

The design proposal, installation, construction requirements and monitoring methods for the 220 kV substation grounding grid were clearly explained and recommended for implementation.

This paper has some guidance on design ideas and the selection method for substation sacrificial anode cathodic protection.

High-silicon chromium iron (HSCI) has been used in ground grids in southern China, while there was a lack of study on its corrosion behavior in this soil environment. The purpose of this paper is to discover the corrosion of HSCI in acidic and alkaline soil solutions.

The original defects on the HSCI surface were observed using optical microscopy, and the corrosion behavior of the HSCI in the acidic and alkaline soil solutions were jointly detected using electrochemical measurements and scanning electron microscopy/energy dispersive spectrometer.

The results showed the corrosion rates of the HSCI in the acidic and alkaline soil solutions were limited, and the high contents of Cr and Si in matrix was responsible for its high corrosion resistance. The HSCI showed a similar corrosion tendency in the two solutions, while its corrosion rate in the acid soil solution was higher than that in the alkaline soil solution. The corrosion pits on the specimen surface were originated from the original defects in matrix, and the edges of the corrosion pits were more rounded than the original defects after 720 h immersion in the two solutions. The original defects in the HSCI matrix played a significant role in the corrosion process.

The paper discovered the corrosion evolution of HSCI in the acidic and alkaline soil solutions. What is more, the acceleration role of the original defects on the corrosion of the HSCI in the acidic and alkaline soil solutions was discovered in the paper. The results are beneficial for the material selection of ground grid equipment in engineering.

The purpose of this paper is to study the corrosion behavior of Q235 steel in saturated acidic red and yellow soils.

The corrosion behavior of Q235 steel in saturated red and yellow soils was compared by weight-loss, SEM/EDS, 3D ultra-depth microscopy and electrochemical measurements.

R_p of the steel gradually increases and i_corr gradually decreases in both the red and yellow soils with time. The R_p of the steel in the red soil is lower, but its i_corr is higher than that in the yellow soil. The uniform corrosion rate, diameter and density of the corrosion pit on the steel surface in the red soil are greater than those in the yellow soil. Lower pH, higher contents of corrosive anions and high-valence Fe oxides in the red soil are responsible for its higher corrosion rates and local corrosion susceptibility.

This paper investigates the difference in corrosion behavior of carbon steel in saturated acidic red and yellow soils, which can help to understand the mechanism of soil corrosion.

The purpose of this paper is to study the corrosion behavior of Q235 steel in the bentonite-based resistance-reducing agent (RRA) with different infiltration rates of underground water.

The corrosion behavior of the steel in underground water was assessed by weight loss experiment, electrochemical impedance spectroscopy and polarization curve.

The results showed that the corrosion rate of the steel in the RRA pastes was much lower than that in the original acidic soil. The underground water infiltration slightly accelerated the corrosion rate of the steel in the RRA pastes, but the acceleration role is weak. The bentonite-based RRA can be compatibly applied in the acidic soil.

The bentonite-based RRA can significantly reduce the corrosion rate of the steel and is suitable to compatibly apply in the acidic soil.

The purpose of this paper is to develop a technological method of protection against electrical corrosion. One more way to protect the objects is to prevent the electrical current from getting to them. For example, railway objects are surrounded with a material with raised electrical resistance.

The railway infrastructure objects (foundations, contact-line supports, reinforced concrete sub-bases, bridge structures, pipelines of engineering networks, supports of passenger platforms and pedestrian bridges, concrete plinth walls of station buildings) are subjected to destruction due to the action of electrical current. One of destruction factors is a corrosion of the concrete constructions which is caused by the leakage current action.

Leakage currents and stray currents bypass the structure of supports of high passenger platforms or pipes of engineering networks. These currents spread by the line with the least resistance outside of the structures.

Electrical leakage current from the rails gets into such structures through sleepers, ballast and soil and leads to accelerated corrosion leaching of concrete.

The constructions are protected against the destructive effect of electrical corrosion on the metal or concrete of the structure. This scheme is suitable for the construction and reconstruction of railway structures which operate on electrified sections of railways.

Schemes of technological solution are proposed for protection of foundations, supports of high passenger platforms, pipelines of engineering networks, etc. For this, the arrangement of soil-contained screens with big electrical resistance is suggested.

The purpose of this paper is to study the influence of moisture on corrosion behaviour of steel ground rods in mildly desertified soil and the mechanism behind it.

The specimens were used for weight loss corrosion experiments and polarization scans were taken at different moisture levels. Specimen surfaces were characterized using a scanning electron microscope, energy dispersive spectrometer, and using X‐ray diffraction.

The results indicated that the moisture content of the soil influenced steel corrosion considerably. The maximum corrosion of 20G and Q235 galvanised steels occurred at 10 per cent and 12.5 per cent soil moisture, respectively. The corrosion products of 20G steel were mostly Fe₂O₃ and Fe₃O₄, whereas that of Q235 galvanised steel was Zn₅(OH)₈Cl₂ · H₂O.

The paper provides information regarding the relationship between moisture and corrosion of steel ground rods, which is useful for understanding the mechanism of soil corrosion. The research results can provide theoretical guidelines for preventing the corrosion of steel ground rods buried in mildly desertified soil.

The corrosion of buried steel pipelines is becoming more serious because of stress corrosion, stray current corrosion and other reasons. This paper aims to study the various alternating current (AC) interference densities on the stress corrosion cracking behaviors of X80 steel samples under cathodic protection (CP) in the simulated soil electrolyte environment by using an electrochemical method.

The change of corrosion rate and surface morphology of the X80 steel samples at various AC current densities from 0 to 150 A/m² or CP potential between −750 and −1,200 mV in the soil-simulating environment was revealed by the electrochemical methods and slow strain rate testing methods.

The results revealed that with the increase of interference density, the corrosion potential of the X80 steel samples shifted to the negative side, and the corrosion pitting was observed on the surface of the sample, this may cause a danger of energy leak. Moreover, the corrosion rate was found to follow a corresponding change with the stress–strain curve. Besides, with the introduction of the CP system, the corrosion rate of the X80 steel working electrode decreased at a low cathodic potential, while showed an opposite behavior at high cathodic potential. In this study, the correlation between AC stray current, cathodic potential and stress was established, which is beneficial to the protection of oil and gas pipeline.

Investigation results are of benefit to provide a new CP strategy under the interference of AC stray current corrosion and stress corrosion to reduce the corrosion rate of buried pipelines and improve the safety of pipeline transportation.

Gives introductory remarks about chapter 1 of this group of 31 papers, from ISEF 1999 Proceedings, in the methodologies for field analysis, in the electromagnetic community. Observes that computer package implementation theory contributes to clarification. Discusses the areas covered by some of the papers ‐ such as artificial intelligence using fuzzy logic. Includes applications such as permanent magnets and looks at eddy current problems. States the finite element method is currently the most popular method used for field computation. Closes by pointing out the amalgam of topics.

The purpose of the paper was to design an anti-corrosion system that combined conductive coatings with cathodic protection for a 500-kV substation ground grid, and provide a basis for the anti-corrosion construction of the installation.

The study took the Shaoguan 500-kV substation grounding grid as the research object. The anti-corrosion performance of KV conductive coatings on grounding metal was researched. In parallel, the alkalinity of substation soil was evaluated according to the German DIN50929 Standard, and the combined protection system comprising conductive coatings and impressed current cathodic protection was designed.

KV conductive coatings, that have resistance to acids, alkalis and salts, can effectively slow down the corrosion rate of the grounding grid. The investigation also provided the outline design, installation, construction requirements and monitoring methods for the 500-kV substation grounding grid.

This report contains some guiding significance for anti-corrosion engineering of 500-kV substation grounding grids.