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Improvement of Microstructure and Barrier Properties of Silicate Coatings on Low Carbon Steel by Incorporating Colloidal Nano-SiO2

Majdi M. R., Danaee I., Zaarei D., Farzam M.

Archives of Metallurgy and Materials

2020

Vol. 65, iss. 2

627--638

Silicate coatings have been considered as an alternative to toxic and carcinogenic other chemical treatments. In this paper, a strengthened silicate coating was formed on the surface of low carbon steel by dip immersion method. The modification and strengthening was done by loading colloidal nano-SiO2 into the film. The characterizations of nano-SiO2 were investigated by FESEM, TEM and FT-IR. The effects of nano contents (weight ratio) and drying temperatures on corrosion properties of silicate film were studied. Potentiodynamic polarization, electrochemical impedance spectroscopy and immersion tests have been used to study corrosion behavior of nano-loaded silicate films. Surface morphology, microstructure and its chemical composition were analyzed by means of FESEM, EDS, AFM, XRD, GIXRD, ATR-FTIR and Raman techniques. Results indicated that colloidal nano-SiO2 properly modified the silicate coatings and significantly improved the corrosion resistance and barrier property. Also drying temperature showed a considerable effect in silicate coating and higher corrosion resistance was obtained with 150°C curing.

Biological Soil Crusts, Plant Functional Groups, and Soil Parameters in Arid Areas of Iran

Bashtian M. H., Sepehr A., Farzam M., Bahreini M.

Polish Journal of Ecology

2018

Vol. 66, nr 4

337--351

Biological soil crusts (BSCs) have a vital role regarding vegetation and soil development in arid and semi-arid areas in the world, and apparently in Iran, where they comprise more than 85% of the land. In this research, the relationship between BSCs and plant functional groups, considering soil parameters along an arid alluvial fan located in Khorasan Razavi province in northeastern Iran, was examined. The sampling carried out in summer, systematically from apex towards base part of alluvial fan, using a 0.25 m2 quadrat over a 5-cm thick soil surface. Surface levels were classified into three categories: apex, middle, and base. At each level, 16 samples were taken; in total 48 samples were collected along the alluvial fan from the apex point to the base district. The results showed a strong relationship between BSCs and the soil surface features, and a weak correlation between the plant functional group and soil parameters. BSCs indicated an ecological evolution from apex to the base geomorphic level by soil development; so that BSCs are more developed on the base of alluvial fan, but their diversity is reduced.