2-Silalactones

Several methods have been developed for the synthesis of 2-silalactones in which the silicon atom is bound to an oxygen atom. Some chemical reactions of these compounds have been studied.     

Simple Method for Stabilizing Solution pH in an Electrochemical Cell

A method is proposed for stabilizing solution pH inside an electrochemical cell. During the working electrode polarization, an electrolyte of the same composition as that of the working one, but with a different pH value is continuously added into the cell. Its pH value and rate of addition are selected so as to compensate variations in the electrolyte's acidity occurring in the cell.     

Synthesis of silalactams

The action of ammonia or primary aliphatic amines on dialky-lchlorosilyl-substituted carboxylic acid chlorides has given silalactams and N-alkylsilalactams, which are readily hydrolyzed by water with the formation of siloxanedicarboxamides.     

Disintegration of 1-silalactones under the influence of electron impact

It is shown that the paths of fragmentation of 1-silalactones under the influence of electron impact are determined by the ring size and remain virtually unchanged when the methyl groups attached to the silicon atom are replaced by a chlorine atom or an ethyl group. The possibility of the identification of isomeric silalactones on the basis of their mass spectra was established.     

Corrosion behavior of aluminum in 1 M HCl solution

The corrosion behavior of pure (99.999) aluminum in 1 M HCl solution is studied. The regularities of local gas evolution on the surface of test specimen at the open-circuit potential are determined. A number of sites, where hydrogen gas evolves, varies with the time passing through a maximum. The sizes of bubbles prior to their detachment from the specimen surface are determined. The time dependences of gas bubble radius in the course of the bubble growth are obtained. From the experimental results, it is concluded that, at the sites of hydrogen gas evolution, the cathodic reaction prevails, whereas the anodic reaction (aluminum etching) proceeds at the rest specimen surface area. No pits form at the sites of hydrogen evolution during the experiments (up to 5 h). The quantitative analysis of the cathodic polarization curve enabled us to estimate the rate (the corrosion current density) of almost general corrosion after the decay of local gas evolution. The long-term experiments (for 2 months) showed that the pitting corrosion of pure aluminum takes place in 1 M HCl.     

Electrochemical Properties of Carbon Black AD-100 and AD-100 Promoted with Pyropolymer of Cobalt Tetra(p-methoxyphenyl)porphyrin

Carbon black AD-100: initial, activated, and promoted with pyropolymer of cobalt tetra(p-methoxyphenyl)porphyrin is characterized by a complex of electrochemical (floating electrode, rotating disk electrode, rotating ring-disk electrode, electrochemical impedance) and structural (standard porosimetry, BET) methods of investigation. Procedures for the AD-100 activation and promotion and the preparation of thin layers of the material to be studied and deposited on disk electrodes are described. The effect of the activation and promotion of carbon black on the surface and electrocatalytic activity of materials under study in the reduction of oxygen and hydrogen peroxide is shown. The ratio of constants of oxygen reduction directly to water and through intermediate formation of hydrogen peroxide is determined. A path for the oxygen reduction is discussed.     

Effect of Dissolved Oxygen on the Corrosion Rate of Stainless Steel in a Sodium Chloride Solution

Russian Journal of Electrochemistry - The corrosion currents of 17-4РН stainless steel in an NaCl solution at various contents of dissolved oxygen are obtained by the method of Tafel...     

Determination of AISI 304 Steel Corrosion Rate in the HCl Solutions by the Method of Measuring Specimen Ohmic Resistance

Russian Journal of Electrochemistry - Using the method of measuring ohmic resistance of steel AISI 304 specimens, the time dependence of steel corrosion rate in the 0.1–2 M HCl solutions is...     

Development of pitting corrosion on 20Kh13 steel

The nucleation and propagation of corrosion pits on 20Kh13 steel in the NaCl solutions with various concentrations, temperatures, and pH values are studied under the potentiostatic conditions and at the free-corrosion potential. In the potentiostatic experiments, the variations of the depth and diameter of pits and their number with the time are determined. It is shown that the state of metal surface in a certain area adjacent to the active pits changes. The dimensions of the area are estimated. The results, which were obtained at the free-corrosion potential, were much less reproducible. At the free-corrosion potential, in contrast to the potentiostatic conditions, the pit depth increased only slightly and the pit width increased to a larger extent. It is shown that the pH value of NaCl solutions has a pronounced effect on the development of pitting corrosion on 20Kh13 steel.     

Effect of doping and heat treatment on the mechanical parameters of ZnSe<Subscript>(1 − <Emphasis Type="Italic">x</Emphasis>)</Subscript>Te<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> crystals grown from the melt

The mechanical properties of crystals of ZnSe_{(1 − x)}Te _x (0 < x < 1.3 wt %) solid solutions are investigated using the indentation method. The breaking points of doped and undoped crystals are measured by the uniaxial compression method. It is revealed that the microhardness anisotropy coefficient for crystals with a tellurium dopant content of ∼0.3 wt % is equal to unity. A change in the tellurium content in the solid solutions from 0.2 to 1.3 wt % leads to a linear increase in the microhardness by 23%. The brittle strength of the ZnSe and ZnSe_{(1 − x)}Te _x crystals varies in a similar manner. It is demonstrated that heat treatment and the presence of interblock boundaries affect the ultimate strength and the cracking resistance of the ZnSe_{(1 − x)}Te _x crystals. This is an important factor which should be taken into account in mechanical treatment of the materials under investigation.