The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform

F I Danilov - One of the best experts on this subject based on the ideXlab platform.

  • unusual chemical mechanism of carbon co deposition in cr c alloy electrodeposition process from trivalent chromium bath
    Electrochemistry Communications, 2012
    Co-Authors: V S Protsenko, V O Gordiienko, F I Danilov
    Abstract:

    Kinetics and mechanism of chromium-carbon alloy deposition process were investigated using trivalent chromium electroplating bath containing formic acid and Carbamide (Urea). The rate of carbon co-deposition process is determined by the rate of chromium electroplating reaction (electrochemical process of Cr-deposition imposes its own kinetics regularities on carbon co-deposition). It was supposed that a part of active chromium ad-atoms generated as a result of Cr(II) ions discharge may interact with adsorbed organic bath constituents by "chemical" mechanism.

  • Unusual 'chemical' mechanism of carbon co-deposition in Cr-C alloy electrodeposition process from trivalent chromium bath
    Elsevier, 2012
    Co-Authors: V S Protsenko, V O Gordiienko, F I Danilov
    Abstract:

    Kinetics and mechanism of chromium-carbon alloy deposition process were investigated using trivalent chromium electroplating bath containing formic acid and Carbamide (Urea). The rate of carbon co-deposition process is determined by the rate of chromium electroplating reaction (electrochemical process of Cr-deposition imposes its own kinetics regularities on carbon co-deposition). It was supposed that a part of active chromium ad-atoms generated as a result of Cr(II) ions discharge may interact with adsorbed organic bath constituents by ''chemical'' mechanism. Keywords: Chromium-carbon electrodeposition, Kinetics and mechanism, Trivalent chromium bat

V S Protsenko - One of the best experts on this subject based on the ideXlab platform.

  • unusual chemical mechanism of carbon co deposition in cr c alloy electrodeposition process from trivalent chromium bath
    Electrochemistry Communications, 2012
    Co-Authors: V S Protsenko, V O Gordiienko, F I Danilov
    Abstract:

    Kinetics and mechanism of chromium-carbon alloy deposition process were investigated using trivalent chromium electroplating bath containing formic acid and Carbamide (Urea). The rate of carbon co-deposition process is determined by the rate of chromium electroplating reaction (electrochemical process of Cr-deposition imposes its own kinetics regularities on carbon co-deposition). It was supposed that a part of active chromium ad-atoms generated as a result of Cr(II) ions discharge may interact with adsorbed organic bath constituents by "chemical" mechanism.

  • Unusual 'chemical' mechanism of carbon co-deposition in Cr-C alloy electrodeposition process from trivalent chromium bath
    Elsevier, 2012
    Co-Authors: V S Protsenko, V O Gordiienko, F I Danilov
    Abstract:

    Kinetics and mechanism of chromium-carbon alloy deposition process were investigated using trivalent chromium electroplating bath containing formic acid and Carbamide (Urea). The rate of carbon co-deposition process is determined by the rate of chromium electroplating reaction (electrochemical process of Cr-deposition imposes its own kinetics regularities on carbon co-deposition). It was supposed that a part of active chromium ad-atoms generated as a result of Cr(II) ions discharge may interact with adsorbed organic bath constituents by ''chemical'' mechanism. Keywords: Chromium-carbon electrodeposition, Kinetics and mechanism, Trivalent chromium bat

  • Electrodeposition of chromium coatings from sulfate–Carbamide electrolytes based on Cr(III) compounds
    Materials Science, 2011
    Co-Authors: V. O. Hordienko, V S Protsenko, S. C. Kwon, J.-y. Lee, F. I. Danilov
    Abstract:

    We propose an electrolyte based on chromium sulfate (1 mole/liter Cr(III)) and containing both formic acid and Carbamide (Urea). This electrolyte enables one to get Cr coatings with a thickness of several micrometers. It is shown that the current yield and deposition rate increase as the current density and pH value increase and temperature decreases. We select the optimal conditions of electrolysis under which bright high-quality chromium deposits are obtained. In this case, the deposition rate of the metal varies from 0.5 to 1.5 μm/min. It is shown that the optimal concentration of both formic acid and Carbamide is equal to 0.5 mole/liter. The necessity of using certain surface-active substances to prevent the formation of pitting on the surface of the deposit is demonstrated. Moreover, it is discovered that the microhardness of Cr deposits attains its highest values (950–980kg/mm^2) for currents with densities of 30–35 A⋅dm^−2 and decreases as the pH value and temperature increase. Electrolysis is realized by using titanium–manganese-dioxide anodes and, hence, it is not necessary to separate the cathodic and anodic spaces.

V O Gordiienko - One of the best experts on this subject based on the ideXlab platform.

  • unusual chemical mechanism of carbon co deposition in cr c alloy electrodeposition process from trivalent chromium bath
    Electrochemistry Communications, 2012
    Co-Authors: V S Protsenko, V O Gordiienko, F I Danilov
    Abstract:

    Kinetics and mechanism of chromium-carbon alloy deposition process were investigated using trivalent chromium electroplating bath containing formic acid and Carbamide (Urea). The rate of carbon co-deposition process is determined by the rate of chromium electroplating reaction (electrochemical process of Cr-deposition imposes its own kinetics regularities on carbon co-deposition). It was supposed that a part of active chromium ad-atoms generated as a result of Cr(II) ions discharge may interact with adsorbed organic bath constituents by "chemical" mechanism.

  • Unusual 'chemical' mechanism of carbon co-deposition in Cr-C alloy electrodeposition process from trivalent chromium bath
    Elsevier, 2012
    Co-Authors: V S Protsenko, V O Gordiienko, F I Danilov
    Abstract:

    Kinetics and mechanism of chromium-carbon alloy deposition process were investigated using trivalent chromium electroplating bath containing formic acid and Carbamide (Urea). The rate of carbon co-deposition process is determined by the rate of chromium electroplating reaction (electrochemical process of Cr-deposition imposes its own kinetics regularities on carbon co-deposition). It was supposed that a part of active chromium ad-atoms generated as a result of Cr(II) ions discharge may interact with adsorbed organic bath constituents by ''chemical'' mechanism. Keywords: Chromium-carbon electrodeposition, Kinetics and mechanism, Trivalent chromium bat

P A Brunton - One of the best experts on this subject based on the ideXlab platform.

  • Research Summary: The effect of bleaching on tooth enamel
    British Dental Journal, 2005
    Co-Authors: P A Brunton
    Abstract:

    Introduction The purpose of this in vitro study was to determine if enamel that had been bleached by Carbamide (Urea) peroxide gel (CPG) was at increased risk of either acid erosion or demineralisation (early caries) than un-bleached enamel. Methods Human incisors were employed. The samples were randomly assigned to one of 4 groups; a) 10% CPG, b) 16% CPG, c) 22% CPG and d) 10% CPG with xylitol, fluoride and potassium. Each specimen was moistened with saliva and the appropriate formulation placed for 2 hours for a total of 40 hours of exposure. In order to ensure that bleaching had taken place, tooth shades were monitored using the Shade-Eye device. Following the bleaching process, one half of the specimen was subjected to an erosive challenge, the other to a demineralisation system with one half of each sub-sample retained as a non-bleached control. Samples were assessed longitudinally with quantitative light-induced fluorescence (QLF) and at the conclusion of the study with transverse micro-radiography (TMR). Results Erosion was detected in all samples (DQ 126±23.4), in both bleached and non-bleached areas. There was no statistical difference between the bleached and non-bleached areas either within the treatment groups or between them. Caries-like lesions were detected on all samples; TMR revealed sub-surface lesions on all teeth and QLF data supported this (DQ 89±18.9). Following statistical analysis there were no differences detected between the bleached and non-bleached areas, nor between the different concentrations of the bleaching solution. Conclusion These results suggest that tooth bleaching with Carbamide (Urea) peroxide (using commercially available concentrations) does not increase the susceptibility of enamel to acid erosion or caries.

  • The effect of bleaching on tooth enamel
    British Dental Journal, 2005
    Co-Authors: P A Brunton
    Abstract:

    Introduction The purpose of this in vitro study was to determine if enamel that had been bleached by Carbamide (Urea) peroxide gel (CPG) was at increased risk of either acid erosion or demineralisation (early caries) than un-bleached enamel. Methods Human incisors were employed. The samples were randomly assigned to one of 4 groups; a) 10% CPG, b) 16% CPG, c) 22% CPG and d) 10% CPG with xylitol, fluoride and potassium. Each specimen was moistened with saliva and the appropriate formulation placed for 2 hours for a total of 40 hours of exposure. In order to ensure that bleaching had taken place, tooth shades were monitored using the Shade-Eye device. Following the bleaching process, one half of the specimen was subjected to an erosive challenge, the other to a demineralisation system with one half of each sub-sample retained as a non-bleached control. Samples were assessed longitudinally with quantitative light-induced fluorescence (QLF) and at the conclusion of the study with transverse micro-radiography (TMR). Results Erosion was detected in all samples (DQ 126±23.4), in both bleached and non-bleached areas. There was no statistical difference between the bleached and non-bleached areas either within the treatment groups or between them. Caries-like lesions were detected on all samples; TMR revealed sub-surface lesions on all teeth and QLF data supported this (DQ 89±18.9). Following statistical analysis there were no differences detected between the bleached and non-bleached areas, nor between the different concentrations of the bleaching solution. Conclusion These results suggest that tooth bleaching with Carbamide (Urea) peroxide (using commercially available concentrations) does not increase the susceptibility of enamel to acid erosion or caries. Concentration of Carbamide peroxide does not appear to effect bleaching efficacy. Bleached teeth, in vitro , are not more susceptible to acid erosion. Bleached teeth, in vitro , are not more susceptible to caries. These results should prove encouraging to those individuals seeking, and providing bleaching treatments.

Hartmut Dr.rer.nat. Baur - One of the best experts on this subject based on the ideXlab platform.

  • High-porosity titanium, stainless steel and superalloy parts
    Advanced Engineering Materials, 2000
    Co-Authors: Martin Bram, Cornelia Stiller, Hans Peter Buchkremer, Detlev Stöver, Hartmut Dr.rer.nat. Baur
    Abstract:

    The production of highly porous parts from titanium, stainless steel, and nickel-based superalloys is of increasing interest in lightweight constructions. A new space-holder method uses Carbamide (Urea) and ammonium hydrogen carbonate to produce samples with porosities between 60 and 80 %. Depending on the shape and size distribution of the space holder, spherical and angular pores in the range of 0.1-2.5 mm were obtained.