Sintered NdFeB magnets possess excellent magnetic properties, but behave passively in alkaline and saline media and are susceptible to corrosion in acidic environments. The corrosion behavior of NdFeB magnets in industrial environments: potassium hydroxide (KOH), perchloric acid (HClO4) and sodium chloride (NaCl), was investigated by immersion and electrochemical tests. The immersion test concluded that the most corrosive electrolyte of the three studied was HClO4. Electrochemical tests showed that the NdFeB sample without magnetic order had better corrosion resistance. Metallographic microscopy and scanning electron microscopy support the obtained corrosion data. X-ray photoelectron spectroscopy indicates that the main elements on the surface of the analyzed sample (Nd, Fe, B) are in the oxidized state after corrosion.

Resumen En este estudio se investigó el comportamiento a la corrosión de los aceros al carbono SR355JR y S355J2 expuestos a diferentes aguas marinas (Mar Negro, Mar Egeo y Mar Mediterráneo) mediante mediciones de polarización. Se calcularon los parámetros de corrosión correspondientes. Se obtuvieron imágenes micrográficas antes y después de la inmersión en el medio corrosivo de las aguas marinas utilizadas. Para determinar la influencia del proceso de corrosión en la estructura cristalina y la magnetización específica de los aceros estudiados se utilizaron los métodos de difracción de rayos X y ponderomotivos respectivamente.

Abstract The corrosion behaviour of SR355JR and S355J2 carbon steels exposed to different seawaters (Black, Aegean and Mediterranean Sea) has been investigated by polarization measurements. The corresponding corrosion parameters were calculated. Micrographic images before and after immersion in the used seawaters corrosive medium were obtained. X-ray diffraction and ponderomotive methods respectively were used to determine the influence of the corrosion process on the crystal structure and specific magnetization of the studied steels.

High temperature ionic liquids (HTILs) densities and transport properties for mixtures BaCl2 CsCl, x(BaCl2) = 0-1, have been studied as a function of composition and temperature. In terms of Arrhenius theory, the temperature correlation of all measured properties was made and discussed. Thermodynamic properties (isothermal compressibility, molecular volume, lattice energy, heat capacity, molar Gibbs energy, enthalpy and entropy) were derived for all the studied HTILs from experimental data. The viscosity isotherms show negative deviations from linearity, while conductivity isotherms have positive deviations which may be related to the formation of highly negative changed ion associated species. The evolution of the excess quantities: viscosity deviation (∆η), excess molar viscosity (∆Eη), excess molar conductivity (∆Eκ), show a very good parallelism. The linear behavior between conductivity and viscosity was determined using the fractional Walden rule and the average slope was found far from unity.