No abstract

The article deals with the role of electrodes materials in improving the industrial wastewater treatment from pollutants by electrochemical action. The instability constants of the complexes and coordinated ligand molecules were calculated. Based on the research conducted regarding the rationalisation of the poly-ligand electrolytes and electrolysis modes, a variative flow scheme of the coatings deposition by triple alloy has been developed. The corrosion resistance characteristics of the coatings obtained in the form of alloy, that were obtained from complex electrolyte that satisfy the necessary coatings requirements for effective treatment of wastewater have been researched. The obtained coatings have better corrosion resistance than in special steels of electrochemical purpose.

The main problem in the production of bimetals (BMs) is the need to ensure adhesive interaction at the contact boundary of layers to prevent their peeling during operation. Hot forging of porous preforms (HFPP) provides the possibility of obtaining high-density powder BMs with a minimum amount of pores both in the volume of the layer material and at the layer interface to increase adhesion strength. Production of hot-forged powder BMs may involve mixing of working layer and substrate charge materials, which can lead to uncontrolled interface «blurring». This study uses the previously proposed method for pre-pressing of hard-to-deform material powder to produce «structural steel – high-speed steel» porous BM preforms. Two-layer cylindrical ∅20×30 mm samples were obtained in order to determine mechanical properties and conduct structural analysis. The BM base material was PK40 steel, and the working layer was atomized powder of M2 high-speed steel featuring satisfactory compressibility properties. The porous preforms of BM samples were pressed in a specially designed mold at a hydraulic press enabling two-sided pressing of two-layer powder moldings with predetermined distribution of layer densities and strengths. Cold-pressed BM preforms were sintered in protective environment, and then subjected to hot repressing using a laboratory drop hammer. Some preforms were examined as sintered. In addition, hot repressing of cold-pressed green preforms was performed. Satisfactory process strength of the working layer material is observed at its porosity (Pwl) in the range from 34 to 45 %. When Pwl> 45 %, powder is not molded, and at Pwl< 34 % the working layer delaminates. The maximum layer bonding strength and thermal shock resistance of BM provides the use of a flow route that involves preliminary sintering of cold-pressed preforms and subsequent hot forging. The optimum pressure of working layer pre-pressing is 145 MPa.

One of the factors limiting the operation time of nuclear reactor is corrosive wear of the reactor core structural materials and fuel element cladding due to continuous action of water coolant. Thus, for VVER (water-water energetic reactor) type reactors, local galvanic corrosion, which occurs between the surface of fuel element cladding made of zirconium alloy and various grade steel parts of other structural elements is peculiar. A short-circuited galvanic cell formed on the inner wall of Zr + 1% Nb alloy fuel elements is shown. Changes in oxide films thicknesses depending on the time at different water medium acidity are analyzed. A generalized model demonstrating that dissimilar metals in the reactor core (zirconium alloy and steel) form a short-circuited galvanic cell, resulting from which an increase in local corrosion of zirconium alloy occurs is presented.

The main attention is paid to the study of processing mechanisms the surface of the electrode affects the kinetics of the electrodeposition of metals from various solutions of their complex salts, as well as improving the technology of obtaining electrolytic powder. Special attention was paid to the detailed study of regularities of the processes occurring during the electrodeposition of copper. Discussed features of the processes of separation of copper powders from solutions of ammonium chloride with addition of complexing polymers of polyacrylamide and polyvinylpyrrolidone's. The basic laws of surface treatment are considered cathode and processes affecting the kinetics of electrodeposition of metals various factors on the particle growth rate and purity of the resulting powders. Researches on improvement of technology of receiving and the intensification of the processes of electrodeposition of copper powders from complex electrolytes'.