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  • Optimization of the reanodization in the production of tantalum oxide-semiconductor capacitors

    A complex of technological operations for the formation of a cathode liner based on manganese dioxide is of particular importance in the production of tantalum oxide-semiconductor capacitors. Electrical characteristics and reliability indicators of capacitors are laid at this stage in their manufacture. In according with the classical technology, the formation of a semiconductor coating of MnO2 on tantalum capacitors is associated with multiple heating of oxidized anodes with the previous impregnation in solutions of manganese nitrate. It has a negative effect on the quality of the Ta2O5-dielectric. To minimize the defect formation in the dielectric, is realized a periodic electrochemical anodization of the tantalum anode in the acetic acid solution by anodic connection of the sections of the capacitors to the direct current source. The authors proposed to modify the process of reanodization of sections of tantalum oxide-semiconductor capacitors by changing the composition of the electrolyte. The results of the investigation of the electrochemical anodizing of a tantalum anode in aqueous solutions of nitric acid and manganese nitrate are presented, the morphology of the obtained coatings, their phase composition, as well as electrical parameters of the sections of capacitors manufactured by the proposed method are analyzed.

    Keywords: Tantalum oxide-semiconductor capacitor, reanodization, manganese nitrate, capacitance, leakage current, dielectric loss tangent, electrolyte

  • Research of the possibility of reducing resistance of the graphite coating in the solid tantalum capacitor

    In recent years, the most widely used semiconductor oxide-tantalum capacitors in high frequency circuits acquired, which causes the need to reduce resistance of the contact and the semiconductor layers. One solution to this problem and at the same time, promising way of improving solid-state tantalum capacitors is to modify process technology for applying the semiconductor layer and heat treatment resistive coating of colloidal graphite. Contact carbon layer according to conventional technology is applied by impregnating the tantalum capacitor sections in an aqueous suspension of colloidal graphite (usually imported), and then produce exposure to air and heat treatment at an elevated temperature. This article presents the results of studies of the effect of conditions of application of the contact layer of colloidal graphite on the electrical characteristics of sections of tantalum oxide-semiconductor capacitor, in particular in the equivalent series resistance, the technique of applying aquadag. Described in detail the design of solid-state tantalum capacitor, the role of the contact carbon layer and its contribution to the ESR of the capacitor.

    Keywords: oxide-semiconductor capacitors, colloidal graphite, resistance of the capacitor, the cathode coating, suspension, immittance, aquadag

  • Chemical regeneration of impregnating solutions Mn(NO3)2 in the manufacturing of oxide-semicanductor capacitors

    "One of the bottlenecks of the production of oxide-semiconductor capacitors is enough fast aging of impregnating solutions of manganese nitrate used to form the cathode electrode of manganese dioxide. This effect is caused by the formation and accumulation of impurities of oxides and nitrides of manganese in the solution, which leads to a poor-quality cathode coating of manganese dioxide on the tantalum anode and as a result, poor performance capacitors. Fast aging of impregnating solutions of the Mn(NO3)2 solutions leads not only to an increase in the cost of materials, but also significantly increases of the volume of waste. As a solution to this problem in the proposed article discusses aspects of chemical regeneration of contaminated solutions of manganese nitrate, analyzed the possible ways of its realization in relation to the existing production of oxide-semiconductor capacitors."

    Keywords: Manganese nitrate, manganese oxides, cathode coating, impregnating solutions, manganese nitrides, manganese oxohydroxide, chemical regeneration.

  • Investigation of ultrasonic treatment influence on stearylamine floccules dispersion in aminobutyric emulsion

    The article presents the investigation of ultrasonic treatment influence on the size of the stearylamine floccules in the aminobutyric emulsion and on the stability of received emulsions. It was found that the amine floccules in the original aminobutyric emulsion have a bimodal size distribution with small particles predominantly 900 nm and large particles with size of 5500 nm or more. It was identified that ultrasonic treatment leads to decrease the stearylamine floccules size in 13-25 times, dimensions of obtained floccules are between 35 and 220 nm. The dynamics of size changes of stearylamine floccules was studied. The stearylamine floccules were obtained in aminobutyric emulsions after the ultrasonic treatment with an intensity of 15-30 W/cm2. It was found that after ultrasonic dispersion the process of amine floccules agglomeration takes place, the duration of this effect depends on the intensity of treatment.

    Keywords: ultrasonic treatment, aminobutyric emulsion, stearylamine floccules, floccules dimensions, emulsion stability

  • Kinetics of sylvinite ore desliming under ultrasonic treatment

    Operation of sylvinite ore desliming is an important step of potassium chloride production by floatation method. It is known that ultrasonic treatment is applied to increase the efficiency of insoluble rest separating from an ore. The purpose was to establish kinetic regularities of the insoluble rest removal from sylvinite ore crystals of the same particle size distribution. Investigations were carried out with mechanical stirring and sonication of varying intensity. It is established that process of sylvinite ore desliming occurs in the diffusion mode. Application of ultrasonic treatment allows to intensify process in 2-4 times as compared with mechanical desliming. Influence of sylvinite ore treatment parameters to chemical composition changing of the insoluble rest is defined. It is shown that sonication for 90 seconds leads to removing carbonates from ore crystals withal concentrating of the iron compounds.

    Keywords: desliming, sylvinite ore, ultrasonic treatment, sonication, insoluble rest.

  • Influence of the manganese nitrate surface phenomena characteristics on impregnating tantalum capacitor anode

    The influence of manganese nitrate impregnating solutions concentration and temperature dynamic viscosity, the wetting angle, interface “porous tantalum electrode - solution” free surface energy and the impregnation degree of porous tantalum anode was researched. A quantitative characteristic of manganese nitrate solution application on porous tantalum anode of solid-electrolyte capacitor during the process of impregnation was defined and work of adhesion and cohesion was calculated. Thus increasing of solution concentration above 42% wt brings to sharp growth of surface tension and so work of cohesion is increased but carriers impregnation is fallen. The most effective impregnation is realized at concentration 27% wt. This fact corresponds to best value of tantalum anode capacitor free surface energy. So using received data we are able to estimate optimal conditions of impregnation and wetting process by nitrate magnesium.  

    Keywords: manganese nitrate, manganese dioxide, limiting wetting angle, free surface energy

  • Sylvinite ore desliming under ultrasonic treatment

    The process of sylvinite ores desliming with ultrasonic treatment is considered. The influence of frequency, intensity and duration of impact to the insoluble rest removal efficiency of sylvinite ores crystals is defined. The optimum mode of sylvinite ores desliming with ultrasonic treatment is established.

    Keywords: desliming, desliming degree, sylvinite ore, ultrasonic treatment, insoluble rest