Corrosion of metals and its prevention

Corrosion is the deterioration of materials by chemical interaction with their environment. The term corrosion is sometimes also applied to the degradation of plastics, concrete and wood, but generally refers to metals. The most widely used metal is iron (usually as steel) and the foieowing discussion is mainly related to its corrosio

Eco-friendly inhibition of mild steel in acidic media

The inhibition effect of Ipomoea carnea plant extract on the corrosion of mild steel has been investigated by weight loss and potentiodynamic polarization techniques. Potentiodynamic polarization study indicated that the plant extracts behave as mixedtype inhibitors. The corrosion rates of the steel and inhibition efficiencies of the extracts were calculated. The results obtained showed that the extract solution of the plant could serve as an effective inhibitor for the corrosion of steel in sulphuric acid media. The corrosion inhibition efficiency increases on increasing plant extract concentration

Localised corrosion of 2124SiCp composite

Influence of alternate immersion in Sodium chloride solution, exposure to salt spray, EXCO test (ASTM-G34), Electrochemical test and marine exposure on 2124 aluminium alloy composite plates reinforced with 10 vol.% SiC particulate and the 2124 base alloy, were studied, and also the localised corrosion like pitting and exfoliation behaviours were reported in this paper

Hydrogen entry into pipeline steel under freely corroding conditions in two corroding media

Hydrogen permeation through API 5L X65 pipeline steel was studied under freely corroding conditions in NACE solution (simulated seawater) and poisoned 1 N H2SO4. A steady state condition with regards to permeation flux is not obtained due to the presence of corrosion product, changing sample dimension and a possible change in hydrogen availability on the corroding surface. A unique way of calculating the sub-surface hydrogen concentration (C0) under non-steady state freely corroding conditions has been developed. The C0 has been evaluated as a function of exposure time in NACE solution and poisoned H2SO4 solution. The sub-surface hydrogen concentration (C0) increased initially but then decreased with increasing exposure to the corroding solutions, after demonstrating an early maximum. The changes in C0 have been explained taking into consideration the corrosion products that developed, the possible anodic reactions, the changes in sample thickness and other issues in the dynamic system

Corrosion protection of steel using waste oils

In the present investigation attempts have been made to develop and evaluate the rust preventive oils to provide temporary corrosion protection of steel structures during transportation as well as agricultural appliances kept idle in the off seasons. For these purposes waste engine oil and used transformer oil were selected, as rust preventive oils, after addition and mixing of some organic inhibitors. For comparison purpose fresh oils and a proprietary oil were also used. The electrochemical method was used to compare the behavior of inhibitors used. Effect of the inhibited as well as uninhibited oils, on rust formation was determined in moistened sulphur dioxide and 10% water mixture of the oils. These tests were performed according to ASTM standard. It was observed that the inhibitor containing heterocyclic secondary amine was more effective in preventing the rust formation and also reduced the corrosion rate in these oils. Studies revealed that used transformer oil inhibited by the organic amino compounds was more effective to reduce the corrosion rate of the mild steel sample

Electrochemical response of amorphous and devitrified Al-Ni-La-X (X = Ag, Cu) alloys

The electrochemical response of melt-spun Al-Ni-La alloys with partial substitution of Ni after different stages of devitrification was studied. The base alloy was found to have the best corrosion resistance. It was observed that primary crystallization caused minimal deterioration in the corrosion resistance of the base alloy as compared to its amorphous state. The substitute alloys had different corrosion resistance dependent on the substituting element with the Ag containing alloy having the least resistance. This could be attributed to the operation of local galvanic cells, enhanced by chemical heterogeneities in the alloys. Secondary crystallization caused a reduction in the corrosion resistance of all the alloys due to the creation of intermetallic phases that increased the galvanic activity

Goethite-arsenite interaction study to understand groundwater arsenic mobilization in the Bengal Delta Plain

Rock-water interaction was studied between goethite and arsenite to understand the mobilization of arsenic from goethite, a major constituent of the Bengal Delta Plain (BDP) matrix. Goethite was synthesized following standard methods of ferrihydrite precipitation and further transformation to goethite. Characterization was carried out using FT-IR, XRD and TEM. As (III) adsorption broadly follows both Langmuir and Freundlich isotherms. As (III) adsorption on goethite was found to be pH dependant. Optimum As (III) loading on goethite has been estimated at 8.93 mg/g for an initial As (III) concentration of 1.04 mg/L

Studies on spectrum density analysis of yarn hairiness variations

92-96<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:calibri;mso-bidi-theme-font:minor-latin;="" color:black;mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:="" ar-sa"="">An attempt has been made to extend the application of spectrum analyser to the textile field for the first time for tracing the yarn hairiness spectrogram from the output signals of Shirley hairiness meter, using 11 yarn samples widely differing in hairiness characteristics. The amplitude and wavelength of the hairiness periodicities would be useful for analyzing the causes of hairiness formation from the point of view of producing quality yarns.</span

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