Papers by Keyword: Electrolyte

Abstract: Established the possibility of galvanochemical obtaining of a plating stronger than in case of chrome precipitation. Proposed precipitation of ternary alloy Co-Мо-W, which allows using the effect of synergism. Proposed and researched usage instead of sulphate-anhydride electrolyte – citrate-diphosphate and ammonia-citrate one. Achieved an increase in current efficiency of precipitated alloy and decrease in current efficiency of hydrogen, with respect to chrome precipitation, which increased safety of the galvanochemical industry. Selected the optimal ratios of components in citrate-diphosphate and ammonia-citrate electrolytes for ternary alloy Co-Мо-W precipitation. Determined the parameters of electrical effect for the galvanic process: constant current – j = 2–8 А/dm², pulse unipolar current – j = 4–20 А/дм². Achieved a high microhardness of this plating and high adhesion to base surface. Achieved greater safety of the galvanochemical technological process of ternary alloy Co-Мо-W application compared with chromium plating.

Abstract: OAbstract. One of the approaches that has been done to produce a better performance of an intermediate temperature solid oxide fuel cell (IT-SOFC) is by varying the synthesis methods. This paper focused on the proton conducting electrolyte in particularly barium cerate and barium zirconate system namely BaCe_0.9Y_0.1O_3-δ (BCY) and BaZr_0.9Y_0.1O_3-δ (BZY). Supercritical ethanol processing technique is one of the alternative synthesis routes that able to produce ceramics powder at lower calcination temperature. The samples were synthesized in High-Pressure-High-Temperature (HP-HT) Batch Wise reactor system using ethanol as reaction medium. XRD was used to study the structure of both samples and all the data were refined using Rietveld refinement method by X’pert Highscore software. VESTA software is used to observe the crystal structure for both BCY and BZY samples. Both BCY and BZY have 98.16% and 96.55% purity after being calcined at 700°C and 1100°C, respectively. This study showed that BCY has orthorhombic structure with lattice parameter a=8.76Å, b=6.24Å and c=6.21Å and BZY exhibited cubic structure with a=b=c, and a=4.194Å. It was observed that BCY synthesized by supercritical fluid (SCF) method at reduced calcination temperature exhibited an acceptable value of lattice paramter as compared to other method that used higher processing temperature.

Abstract: Abstract. Solid oxide fuel cell (SOFC) is an electrochemical conversion device that undergoes a thermal cycling at various operating temperature where lead to the degradation of its mechanical properties. Electrolyte among the main component in SOFC plays a crucial part in defined the overall performance which facing a lattice expansion event when exposed to heating. Thus, in this paper BaCe0.54Zr0.36Y0.1O3-δ (BCZY) was selected as potential electrolyte for intermediate temperature solid oxide fuel cell (IT-SOFC) to investigate its lattice expansion as a function of temperature. The sample was prepared via a sol gel method and calcined at 1100°C for 10 hours to form a powder and then pressed to become a pellet. To ensure a good densification in such pellet, two-steps sintering processes was indicated at 1500°C and ground to a powder form prior to the lattice expansion measurements. High temperature X-ray diffraction (HT-XRD) was used to study the lattice expansion of sample in the temperature range of 25°C to 700°C with interval 100°C under air atmosphere. HT-XRD analysis was done using X’pert Highscore Plus software and Visual for Electronic and Structural Analysis (VESTA) software was used to observe the crystal structure. Phase and structural analysis of BCZY electrolyte materials were discussed. Apparently, the BCZY shows an average of 97% phase purity from room temperature to 700°C. Rietveld refinement analysis revealed that the BaCe0.54Zr0.36Y0.1O3-δ exhibits cubic symmetrical structure with unit cell, a=b=c that varied from 4.3440Å - 4.3731Å for all the temperature studied. Thus, the expansion percentage for the lattice expansion from room temperature to 700°C was about 12.6 %.

Abstract: The processing conditions of the of electronic wastes are largely dependent on environmental standards and requirements. Modern technologies for processing electronic waste should meet the increased demand for metals as well as the requirements. Electronic wastes can be classified as hazardous materials, as household and industrial electrical devices, which contain components such as batteries, capacitors, cathode ray tubes, etc. Electronic waste can consist of a large number of components of various sizes, shapes and chemical composition. Some of them contain hazardous metals, including mercury, lead, cadmium. The presence of precious metals in electronic waste such as gold, silver, platinum, palladium, as well as non-ferrous metals (copper, nickel, zinc, tin, etc.) make it attractive for processing. In industry, both hydrometallurgical and pyrometallurgical methods are used to extract valuable metals from electronic waste. Applied technologies may have both advantages and disadvantages.

Abstract: Anodic oxide films of zinc oxide in an aqueous solution of K Cl (0.1 M; 0.5 M and 1 M) were obtained by electrochemical oxidation of zinc metal. Zinc electrode was used as anode and platinum plate as cathode. The study discusses the influence of the concentrations of K Cl solution and the voltage applied to the electrochemical cell on the morphology of the obtained anode films, as well as their thermodynamic stability. The analysis of volt-ampere curves of linear potential sweep and chronoamperometric dependences showed that oxidation in 0.1 M K Cl solution at a voltage of 7.5 V allows to obtain continuous stable defect-free Zn O films on metal zinc.

Abstract: The results of the research of the use of powders based on tungsten carbide with a particle size of 1 μm or less, obtained by the method of electro-erosion dispersion from the waste of sintered hard alloys, as a dispersed phase of composite galvanic coatings based on iron during the restoration and hardening of car parts are presented. It is shown that the introduction powders of hard alloys of grades VK8 and T15K6 in the chloride electrolyte of iron plating with a concentration of 100 g/l and more, practically does not affect the micro-hardness, but allows to increase the relative wear resistance of the obtained composite galvanic coatings, compared to simple iron galvanic coatings, and, at the same time, increase the life of parts and reduce repair costs.

Abstract: The practice shows availability of an electro plasma method polishing. The lack of a method, namely impossibility of its application for processing extended grooves and apertures is known. Creation of a special equipment and revealing of optimum modes have allowed to receive the given roughness on the named surfaces on products from cuprum.

Abstract: Technological difficulties of manufacture, typical to the large number of crucial elements of certain assemblies: tubes of fuel systems, details of waveguide devices, smooth gun barrels and other tubular details. Difficulties associated with the finishing of the internal surfaces of these products. Therefore, great interest is to find a finishing technology, which allow processing such products. The kind of electrolytic-plasma polishing technology - forced electrolytic-plasma polishing (FEPP) allows to receive homogenous quality of an internal surface layer along processed tubular work piece.

Abstract: Among physical and mechanic properties of coatings the internal stresses are of special interest. Internal stresses include stresses which exist and are counterbalanced within a rigid body in cases when there is no external action which caused them. In coatings obtained on the basis of nickel, chrome they can decrease the adhesive strength, cause cracking, peeling, anticorrosion properties deterioration. But the definite level of internal stresses leads to increase of hardness and coatings wear resistance and also facilitates porous coatings obtaining. The results of theoretical and experimental investigations of the internal stresses that appear in oxide ceramic coatings formed by plasma-electrolytic oxidation (PEO) on aluminum surfaces are presented.

Abstract: The peculiarity of alkali-activated slag cements (further, AASC’s) is increased proper deformations, which can cause increased cracking and reduced durability of structure. The paper is devoted to manage AASC’s proper deformations. The main task was to determine the composition of complex additives (further, CA’s) in system «ordinary portland cement (further, OPC) clinker - mineral compound of different anionic type - surfactant» in presence of sodium metasilicate (further, MS) to affect on hydrated AASC performance while ensuring effective structure of artificial stone by criterion of shrinkage deformations. Comparative analysis of hydrated cement systems "OPC clinker - MS", "OPC clinker - mineral compound - MS" and "OPC clinker - mineral compound - MS - surfactant" showed that the greatest effect on reduction of proper deformations occurs when the mineral compounds relate to electrolytes, i.e. Na₂SO₄ and NaNO₃. Hydrated system is characterized by expansion (+0,062 mm/m) in presence of Na₂SO₄. Almost no shrinkage is supplied by application of NaNO₃ (-0,062 mm/m). The obtained CA’s were tested in AASC. CA in the system “OPC clinker - NaNO₃ - surfactant” provides the initial setting 43 min, the end - 65 min with accelerated strength. Investigated AASC can be classified as non-shrinking cement. This phenomena is ensured by increasing density, homogeneity and monolithicity of hydrosilicate formations, as well as due to formation of hydroaluminosilicate structures with different morphology by inclusion of nitrate anions.