The corrosion behaviour of welded maraging steel in hydrochloric acid solutions was studied over a range of acid concentration and solution temperature by electrochemical techniques like Tafel extrapolation method and electrochemical impedance spectroscopy. The corrosion rate of welded maraging steel increases with the increase in temperature and concentration of hydrochloric acid in the medium. The energies of activation, enthalpy of activation and entropy of activation for the corrosion process were calculated. The surface morphology of the corroded sample was evaluated by surface examination using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).

The inhibition action of 3-ethyl-4-amino-5-mercapto-1,2,4-triazole (EAMT) on the corrosion of 6061-Al alloy in different concentrations of aqueous sodium hydroxide solution has been investigated at different temperatures, using potentiodynamic polarization and electrochemical impedance spectroscopic techniques. The surface morphology of the metal surface was investigated by scanning electron microscopy (SEM). The experimental results showed that the presence of EAMT in sodium hydroxide solution decreases the corrosion rates and the corrosion current densities (icorr), and increases the charge transfer resistance (Rp). It was found that the inhibitor efficiency depends on the concentration of the inhibitor, concentration of the corrosive media and temperature. The inhibition was assumed to occur through adsorption of the inhibitor molecule on the metal surface. The adsorption of the inhibitor on the metal surface is found to obey Langmuir adsorption isotherm. EAMT acts as a mixed inhibitor. Thermodynamic parameters for the adsorption processes were determined from the experimental data. The results obtained from both the techniques are in good agreement.

The corrosion behavior of aged and annealed sample of 18 Ni 250 grade maraging steel was investigated in varied conditions of concentration and temperature of sulphuric acid medium, using electrochemical techniques like Tafel polarization and electrochemical impedance spectroscopy (EIS). The results obtained from both the techniques are in good agreement. These results have shown increase in corrosion rate of aged specimen with increase in concentration and temperature of sulphuric acid. With increase in concentration of sulphuric acid from 0.025 M to 0.25 M the corrosion rate of annealed sample was found to increase, but there after in 0.5 M, 0.75 M and 1 M, the rate of corrosion decreases, indicating passivation of alloy surface at higher concentration of sulphuric acid. The corrosion rate of aged specimen was found to be higher than that of the annealed specimen. Similar observations are revealed by SEM images. The thermodynamic parameters like activation energy, enthalpy of activation and entropy of activation were calculated.

Um método complexométrico simples e seletivo é proposto para a determinação de tálio na presença de outros metais, pela habilidade do etanetiol em mascarar seletivamente íons tálio (III). Em solução, o tálio presente foi inicialmente complexado com um excesso conhecido de EDTA, sendo o excesso titulado com uma solução padrão de sulfato de zinco em pH 5-6 (hexamina), usando-se xilenol como indicador. Uma solução aquosa de etanetiol 0,3 % foi então adicionada para deslocar o EDTA do complexo Tl(III)-EDTA. O EDTA livre foi titulado com solução padrão de sulfato de zinco, como anteriormente. Resultados reprodutíveis e precisos foram obtidos na faixa de 3,70 mg a 74,07 mg de Tl(III), com erro relativo menor do que ± 0,44 % e um coeficiente de variação menor do que 0,27 %. A interferência de vários íons foi estudada e o método foi usado para análise de tálio em misturas de ligas sintéticas e também em complexos.

A simple and selective complexometric method for the determination of thallium in presence of other metal ions is proposed based on the selective masking ability of ethanethiol towards thallium(III). Thallium present in a given sample solution is first complexed with a known excess of EDTA and the surplus EDTA is titrated with standard zinc sulphate solution at pH 5-6(hexamine) using xylenol orange as the indicator. A 0.3% aqueous solution of ethanethiol is then added to displace EDTA from the Tl(III)-EDTA complex. The released EDTA is titrated with standard zinc sulphate solution as before. Reproducible and accurate results are obtained for 3.70 mg to 74.07 mg of Tl (III) with relative error less than ± 0.44% and coefficient of variation not more than 0.27%. The interference of various ions was studied and the method was used for the analysis of thallium in its synthetic alloy mixtures and also in complexes.