Adsorption of the IFKhAN-92 Inhibitor on Chromium–Nickel Steel from Mineral Acid Solutions

Protection of Metals and Physical Chemistry of Surfaces - Impedance spectroscopy was used to study the adsorption of the IFKhAN-92 inhibitor, a triazole derivative, on cathodically polarized...     

Preparation of Exfoliated Graphite Modified with Magnesium Ferrite

A magnetic sorbent based on exfoliated graphite modified with magnesium ferrite has been prepared by impregnating oxidized graphite in a mixed solution of FeCl₃ and Mg(NO₃)₂, followed by heat treatment of the impregnated oxidized graphite in air. X-ray diffraction and Mössbauer spectroscopy results demonstrate that the structure of the magnesium ferrite is an inverse spinel with a degree of inversion of 0.59. The saturation magnetization of the magnesium ferrite-containing exfoliated graphite is 16.1 emu/g, whereas its oil sorption capacity is as high as 54 g/g. Compaction of the exfoliated graphite to a density of 0.03 g/cm³ reduced its sorption capacity to 26 g/g. Further increasing the density of the material led to a considerable decrease in its sorption capacity.     

Protective Aftereffect of IFKhAN-92 Inhibitor for Corrosion of Nickel–Chromium Steel in Hydrochloric Acid

It is shown that the multimolecular protective layer of an organic inhibitor formed on the surface of chromium–nickel steel in an HCl solution containing a triazole derivative, the inhibitor IFKhAN-92, has a protective aftereffect in background solutions of the same acid. Such a protective layer is chemically bonded to the Fe, Cr, and Ni oxide and hydroxide phase adjacent to the metal phase. The lower part of the polymolecular protective layer of the organic inhibitor consists of a polymer complex formed by IFKhAN-92 molecules, metal cations (Fe, Cr, and Ni), and chloride anions, and the outer part consists of physically adsorbed IFKhAN-92 molecules, which are easily removed from the metal surface during ultrasonic washing of samples.

     

Surface modification of carbon fibers with nitric acid solutions

We have studied the surface modification of carbonized carbon fibers with nitric acid solutions, compared the effects of 60 and 98% HNO₃, and examined the influence of the anodic polarization of the fiber for surface functionalization. Unmodified and surface-modified carbon fibers have been characterized by a variety of physicochemical techniques.     

Vapor condensation upon transversal flow around a cylinder (boundary heat-exchange laws)

The problem of vapor condensation upon transversal flow around a horizontal cylinder is considered. The analytical solutions for the “boundary heat-exchange laws” are obtained. The solutions show the dependence of the heat transfer coefficient on the corresponding factor (gravity, interfacial friction, longitudinal pressure gradient) under the assumption that there is no effect of other factors. The boundary laws obtained for moving vapor are shown to depend on pressure in the same manner, while the temperature differential has different effects in specified asymptotics. The theoretical results obtained are used for qualitative analysis of the available experimental data.     

Temperature and Time Effects on the Acid Corrosion of Steel in the Presence of Acetylenic Inhibitors

Potentiostatic and gravimetric methods were used to reveal that the inhibition effect of acetylenic inhibitors (namely propargyl alcohol and propargyl chloride) on the electrode processes of iron and steel corrosion in hydrochloric and sulfuric acids grows with time and temperature, owing to the formation of a polymeric film on the metal surface. In sulfuric acid, propargyl alcohol is easily hydrogenated to give removable reduction products, which lowers its protection effect on steel corrosion.