Inhibition of corrosion of SS 18/8 alloy is sea water by Thiourea-Zn2+ system

The corrosion resistance of SS 18/8 in natural sea water, in presence of an inhibitor named Thiourea-Zn2+ has been evaluated. Weight loss method, polarization study and AC impedance spectra have been employed to evaluate the corrosion resistance of SS 18/8 alloy in natural sea water, in presence of an inhibitor named Thiourea-Zn2+ system. Weight loss method reveals that Thiourea-Zn2+ system offers a maximum corrosion inhibition efficiency of 95% in controlling corrosion of SS 18/8 alloy in natural sea water. Synergism parameters are found to be greater than 1, confirming the synergistic effect existing between Thiourea-Zn2+. Adsorption of inhibitor molecules on the metal surface obey Langmuir adsorption isotherm. Polarisation study reveals that the inhibitors named Thiourea-Zn2+ system functions as mixed type of inhibitor. AC impedance spectra confirm the formation of a protective film on the metal surface. This formulation of Thiourea-Zn2+ may be used in cooling water systems where SS 18/8 alloy pipelines are used to carry sea water which is used as coolant. Also, Thiourea-Zn2+ coating can be given on SS 18/8 alloy to protect it from corrosion by sea water when SS 18/8 alloy is used as hull plates in ship industry.

Inhibition of corrosion of mild steel in well water by an aqueous extract of soapnut (Sapindus Trifoliatus)

Inhibition efficiency of an aqueous extract of soapnut (Sapindus Trifoliatus) and Zn2+in controlling corrosion of mild steel in well water at room temperature has been evaluated by using weight loss method, polarization study and AC impedance spectra. Dynamic light scattering and Vickers hardness have also been employed. Weight loss method reveals that the formulation consisting of 10 ml soapnut extract and 50 ppm Zn2+ has 97 % inhibition efficiency in controlling corrosion of mild steel immersed in well water. Synergism parameters suggest that a synergistic effect exists between soapnut extract and Zn2+. Adsorption isotherm of metal surface obeys Langmuir adsorption isotherm. Polarization study reveals that the inhibitor system functions as anodic type of inhibitor. AC impedance spectra confirm the protective film formed on the metal surface. Dynamic light scattering (DLS) study reveals surface is in nano meter scale. The Vickers hardness of metal surface was increases in inhibitor system.

Inhibition of corrosion of mild steel by an alcoholic extract of a seaweed Sargassum muticum

An alcoholic extract of a sea weed Sargassum muticum has been used to control corrosion of mild steel in 0.5 N HCl. Weight loss method and Electrochemical studies have been used in this study. Weight loss study reveals that 500 ppm of the inhibitor offers 99.25 % inhibition efficiency. Polarization study reveals that the inhibitor functions as an anodic inhibitor at higher concentration. The AC impedance spectra confirm the formation of a protective film on the metal surface. Adsorption of inhibitor molecules on the metal surface follows Langmuir adsorption isotherm.

Corrosion Inhibition by Flower Extracts - At a Glance

Flower extract are ecofriendly corrosion inhibitors. They have been used to control corrosion of mild steel, copper and aluminium in various media. The mechanistic aspects have been investigated by electrochemical studies such as polarisaiton study and AC impedance spectra. The protective film has been analysed by FTIR, SEM, EDX and AFM. The adsorption isotherms isotherms being obeyed are Langmuir, Temkin and Freundlich adsorption isotherms. The flowers extract primarily function as mixed type of inhibitors. The active principles mainly present in colored flowers are anthocyanins, and carotenoids. They contain polar groups such as hydroxyl, methoxy and ether. These ingredients coordinate with the metal ions on the metal surface through oxygen atom, benzene ring and conjugated double bonds. The protective film formed on the metal surface controls the corrosion process. Keywords: Corrosion Inhibition; Flower Extract; AFM; SEM; FTIR; Isotherms; Green Inhibitors

Influence of excess lithium and sintering on the conductivity of Li1.3Al0.3Ti1.7(PO4)3

NASICON-type samples with different amount of excess lithium content in starting materials, Li[Formula: see text]Al[Formula: see text]Ti[Formula: see text](PO4)3 ([Formula: see text]), were prepared by conventional solid-state reaction. Effect of excess lithium and sintering conditions on composition and electrical properties of LATP were investigated. X-ray diffraction and Scanning electron microscopy were used to characterize the composition, crystal structure and morphology, respectively. The total ionic conductivities of samples were measured by AC-impedance spectra. The optimal addition amount of excess Li was found to be 40[Formula: see text]mol.% with the highest conductivity of [Formula: see text][Formula: see text]S/cm at [Formula: see text]C. The improvement of the conductivity of LATP can be attributed to the increasing of Li[Formula: see text] carriers and the formation of glassy phase in samples which acted as binders and provided excess Li ion vacancies for lithium transport.

A Comparative Study on Sintering Behaviour of Low and High Density Pellets of Ni-YSZ by Electrochemical Impedance Spectroscopy

In this study, a systematic investigation on in-situ sintering behavior of Ni-YSZ (50: 50wt. %) pellets of density of 4.2 (low density) and 4.9 g/cm3 (high density) in ambient and oxygen environment by impedance spectroscopy is presented. X-ray diffraction indicated the formation of cubic phases of NiO and YSZ. The low density pellet sintered for 16 h showed low content of monoclinic phase when compared to high density pellet. The microstructure of the high density pellet revealed finer and homogenous distribution of Ni in YSZ matrix due to longer sintering duration when compared with the low density pellet. AC impedance spectra were recorded for both low and high density pellets during sintering in ambient and oxygen environment in the temperature range 873-1173 K. The results indicate that for both the pellets, the impedance values decreased when sintering temperature increased from 873 to 1173 K in both ambient and oxygen environment. However, the impedance was low while sintering in oxygen atmosphere than in ambient. Besides these observation, impedance of the high density pellet was much lower than that of the low density pellet at all sintering temperature in both ambient and oxygen atmosphere. While the impedance decreased with increasing sintering temperature, the capacitance increased slowly in both the ambient and oxygen atmosphere. The change in the impedance behavior due to grain interior and grain boundaries is explained in relation with the microstructural changes that occur during sintering in different environments.