scholarly journals Effect of Aquo-glycolic Media and Added Anions on the Anodization of Zircaloy-4 in Sulphamic Acid

2011 ◽  
Vol 8 (1) ◽  
pp. 71-76
Author(s):  
Viplav Duth Shukla ◽  
CH. Anjaneyulu
Keyword(s):  
Dielectric Constant ◽  
Ethylene Glycol ◽  
Room Temperature ◽  
Film Formation ◽  
Constant Current ◽  
Constant Current Density ◽  
Phosphate Ions ◽  
Sulphamic Acid ◽  
Kinetics Of ◽  
Millimolar Concentration

Anodization of zircaloy-4 in 0.1 M sulphamic acid has been carried out. Kinetics of anodic oxidation of zircaloy-4 has been studied at a constant current density of 8 mA/cm2and at room temperature. Thickness estimates were made from capacitance data. The plots of formation voltagevs. time, reciprocal capacitancevs. time, reciprocal capacitancevs. formation voltage and thicknessvs. formation voltage were drawn and rate of formation, current efficiency and differential field were calculated. The addition of solvent (ethylene glycol) showed better kinetic results. For 25%, 50% and 75% aquo-glycolic media, the dielectric constant values are low leading to a marked improvement in the kinetics. In 80% ethylene glycol, though the dielectric constant value of solution is less, the kinetics was slow which may be attributed to the fact that the electrolyte becomes highly non-polar. Improvement in the kinetics of oxide film formation was observed by the addition of millimolar concentration of anions (CO32-, SO42-, PO43-). The presence of phosphate ions improved the kinetics of anodization to better extent.

Fluorinated SiO2 Films For Interlayer Dielectrics In Quarter-Micron Ulsi Multilevel Interconnections

1995 ◽  
Vol 381 ◽  
Author(s):  
Tetsuya Homma
Keyword(s):  
Residual Stress ◽  
Dielectric Constant ◽  
Room Temperature ◽  
Dielectric Film ◽  
Film Formation ◽  
Pure Water ◽  
Film Deposition ◽  
Interlayer Dielectric ◽  
Interlayer Dielectrics ◽  
Lpd Technique

AbstractFluorinated SiO2 films for use as interlayer dielectrics in ULSI multilevel interconnections are investigated. The interlayer dielectric film properties and their formation techniques have to meet the following requirements: (1) a low dielectric constant, (2) a high planarization capability, (3) a high capability for narrow gap filling, and (4) a low deposition temperature for low residual stress. To satisfy these requirements, three technologies have been investigated. They are: (i) a fluorinated SiO2 (SiOF) film by room temperature chemical vapor deposition (RTCVD-SiOF) using fluorotrialkoxysilane (FTAS) and pure water as gas sources, (ii) a room temperature liquid phase deposition (LPD) SiO2 film, and (iii) a fluorinated spin-on-glass (SOG) film by fluorotrialkoxysilane vapor treatment (FAST-SOG). The dielectric constant for SiO2 films can be reduced to 3.7 at 1 MHz by the RTCVD and LPD techniques. Although the FAST and RTCVD techniques cannot achieve full planarization, the LPD technique can achieve both global and local planarization because this technique has high capability for selective SiO2 film deposition. The RTCVD, FAST and LPD techniques have shown the possibility to reduce the film formation temperature to room temperature by catalytic reactions, resulting in low residual stress. Other properties of the RTCVD-SiOF, LPD-SiO2 and FAST-SOG films are good enough for the interlayer dielectric film application. The LPD-SiO2 film shows higher endurance properties to moisture than the RTCVD-SiOF and FAST-SOG films.

scholarly journals Influence of Anodization on the Fatigue and Corrosion-Fatigue Behaviors of the AZ31B Magnesium Alloy

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1573
Author(s):  
Leandro Antonio de Oliveira ◽  
Silvano Leal dos Santos ◽  
Vinicius Antonio de Oliveira ◽  
Renato Altobelli Antunes
Keyword(s):  
Magnesium Alloy ◽  
Corrosion Fatigue ◽  
Room Temperature ◽  
Fatigue Behavior ◽  
Phosphate Buffer Solution ◽  
Fatigue Tests ◽  
Constant Current ◽  
Buffer Solution ◽  
Constant Current Density ◽  
Az31b Magnesium Alloy

The aim of the present work was to investigate the effect of anodization on the fatigue and corrosion-fatigue behavior of the AZ31B magnesium alloy. Samples were anodized in constant current density mode at 20 mA cm−2 for 5 min at room temperature, in an environmentally friendly electrolyte consisting of a mixture of sodium hydroxide and sodium silicate. Fatigue tests were conducted in air and in phosphate buffer solution (PBS) at room temperature in the tension-tension mode, at a frequency of 5 Hz and stress ratio of 0.1. S-N curves were obtained for polished and anodized samples. Fracture surface morphology was examined by optical stereo-microscopy and scanning electron microscopy. Results indicated that the fatigue limit was reduced approximately 60% at 106 cycles for the anodized specimens, either for the fatigue tests conducted in air or PBS solution. Anodization had a remarkable effect on the fatigue behavior of the AZ31B alloy. The effect of the corrosive environment, in turn, was not significant.

Electrolytic Breakdown of Anodic Films on Aluminum

1971 ◽  
Vol 29 ◽  
pp. 206-207
Author(s):  
J. Zahavi ◽  
M. Metzger
Keyword(s):  
Electron Microscopy ◽  
Steady State ◽  
Sulfuric Acid ◽  
Large Scale ◽  
Film Growth ◽  
Film Formation ◽  
Constant Current ◽  
Anodic Films ◽  
Constant Current Density ◽  
The Stability

Electron microscopy has been used for some time in studying topography and structure of anodic films for identification and measurement of cell and pore structures and for detection of flaws or of various forms of breakdown, but usually at high forming voltages yielding relatively large scale features. For film formation with accompanying dissolution, leading to films of the porous type, the structure at cell voltages of several volts and below is of interest in regard to formation and dissolution mechanisms in general and to the stability and breakdown of corrosion films, in particular. As a first step, we have studied the films on aluminum, of known purity and microstructure, electropolished in a perchloric acid-ethanol bath and formed in 2.4 M sulfuric acid at a relatively low constant current density of 5 ma/cm2 giving steady state conditions of slow film growth at relatively low current efficiency.

Investigation of irradiation-induced nucleation processes in silicon and germanium

1995 ◽  
Vol 53 ◽  
pp. 224-225
Author(s):  
Harry A. Atwater ◽  
C.M. Yang ◽  
K.V. Shcheglov
Keyword(s):  
Room Temperature ◽  
Crystal Size ◽  
Initial Distribution ◽  
Engineering Control ◽  
Size Evolution ◽  
Silicon And Germanium ◽  
Ge Quantum Dot ◽  
And Control ◽  
Germanium Quantum Dots ◽  
Kinetics Of

Studies of the initial stages of nucleation of silicon and germanium have yielded insights that point the way to achievement of engineering control over crystal size evolution at the nanometer scale. In addition to their importance in understanding fundamental issues in nucleation, these studies are relevant to efforts to (i) control the size distributions of silicon and germanium “quantum dots𠇍, which will in turn enable control of the optical properties of these materials, (ii) and control the kinetics of crystallization of amorphous silicon and germanium films on amorphous insulating substrates so as to, e.g., produce crystalline grains of essentially arbitrary size.Ge quantum dot nanocrystals with average sizes between 2 nm and 9 nm were formed by room temperature ion implantation into SiO2, followed by precipitation during thermal anneals at temperatures between 30°C and 1200°C[1]. Surprisingly, it was found that Ge nanocrystal nucleation occurs at room temperature as shown in Fig. 1, and that subsequent microstructural evolution occurred via coarsening of the initial distribution.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Growth Kinetics of Quantum Size ZnO Particles

1998 ◽  
Vol 536 ◽  
Author(s):  
E. M. Wong ◽  
J. E. Bonevich ◽  
P. C. Searson
Keyword(s):  
Growth Kinetics ◽  
Ostwald Ripening ◽  
Chemical Potential ◽  
Colloidal Suspensions ◽  
Green Emission ◽  
Blue Shift ◽  
Constant Current ◽  
Mass Model ◽  
Zno Particles ◽  
Kinetics Of

AbstractColloidal chemistry techniques were used to synthesize ZnO particles in the nanometer size regime. The particle aging kinetics were determined by monitoring the optical band edge absorption and using the effective mass model to approximate the particle size as a function of time. We show that the growth kinetics of the ZnO particles follow the Lifshitz, Slyozov, Wagner theory for Ostwald ripening. In this model, the higher curvature and hence chemical potential of smaller particles provides a driving force for dissolution. The larger particles continue to grow by diffusion limited transport of species dissolved in solution. Thin films were fabricated by constant current electrophoretic deposition (EPD) of the ZnO quantum particles from these colloidal suspensions. All the films exhibited a blue shift relative to the characteristic green emission associated with bulk ZnO. The optical characteristics of the particles in the colloidal suspensions were found to translate to the films.

Kinetics of the Thermal Disappearance of Radicals Formed During the Radiolysis of Aspartic Acid

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Mihai Contineanu ◽  
iulia Contineanu ◽  
Ana Neacsu ◽  
Stefan Perisanu
Keyword(s):  
Thermal Resistance ◽  
Aspartic Acid ◽  
Room Temperature ◽  
Esr Spectra ◽  
Complex Mechanism ◽  
Radical Species ◽  
Mechanisms Of Formation ◽  
Kinetics Of

The radiolysis of the isomers L-, D- and DL- of the aspartic acid, in solid polycrystalline state, was investigated at room temperature. The analysis of their ESR spectra indicated the formation of at least two radicalic entities. The radical, identified as R3, resulting from the deamination of the acid, exhibits the highest concentration and thermal resistance. Possible mechanisms of formation of three radical species are suggested, based also on literature data. The kinetics of the disappearance of radical R3 indicated a complex mechanism. Three possible variants were suggested for this mechanism.

Reducing the Ecotoxicity of Pesticide Polluted Waters by Electrochemical Methods

2019 ◽  
Vol 70 (5) ◽  
pp. 1574-1578
Author(s):  
Cristian Neamtu ◽  
Bogdan Tutunaru ◽  
Adriana Samide ◽  
Alexandru Popescu
Keyword(s):  
Nitrogen Atmosphere ◽  
Constant Current ◽  
Polluted Water ◽  
Gaseous Nitrogen ◽  
Constant Current Density ◽  
Electrochemical Approach ◽  
Saline Waters ◽  
Thermal Combustion ◽  
Polluted Waters ◽  
Thermal Stability Of

Electrochlorination constitutes an electrochemical approach for the treatment of pesticide-containing wastewaters. This study evaluated the electrochemical and thermal stability of four pesticides and the efficiency of electrochlorination to remove and detoxify the simulated polluted water with: Acetamiprid, Emamectin, Imidacloprid and Propineb. This study reports the experimental results obtained by cyclic voltammetry and electrolysis at constant current density in association with UV-Vis spectrophotometry. In saline waters this pesticides are electrochemical active and anodic peaks are registered in the corresponding voltammograms. After thermal combustion, in a gaseous nitrogen atmosphere, a residue ranging from 15 to 45 % is observed at 500 �C.

The diffusion coefficients 110mAg isotope in copper-contained chalcogenide films obtained by chemical deposition

2016 ◽  
Author(s):  
Д.Л. Байдаков
Keyword(s):  
Diffusion Coefficients ◽  
Chalcogenide Glasses ◽  
Film Formation ◽  
Polymer Network ◽  
Chemical Deposition ◽  
Film Deposition ◽  
Constant Current ◽  
Residual Pressure ◽  
Quartz Ampoule ◽  
Chalcogenide Films

Методом химического нанесения из растворов халькогенидных стекол в н-бутиламине получены многокомпонентные халькогенидные пленки CuI-As2Se3, CuI-PbI2-As2Se3, CuI-SbI3-As2Se3, CuI-SbI3-PbI2-As2Se3. Синтез многокомпонентных медьсодержащих халькогенидных стекол, использовавшихся для нанесения пленок, проводили методом вакуумной плавки в кварцевых ампулах при температуре 400…950 °С и остаточном давлении не более 0,13 Па. Закалку стекол производили от 600 °С в воду со льдом с разливом расплава в ампуле. Навеску стекла размельчали в порошок и кипятили в н-бутиламине до полного растворения. Для предотвращения процессов окисления, нанесение и отжиг пленок проводили в атмосфере химически инертного азота. Подложку помещали на устройство для вращения, наносили на нее раствор и вращали подложку со скоростью несколько тысяч оборотов в минуту. Отжиг пленок проводили при температуре 100 °С в течение 1 ч. Измерение электропроводности полученных пленок проводили на постоянном и переменном токе в зависимости от значений электропроводности в температурном интервале 20…100 °С. Измерение коэффициентов диффузии проводили абсорбционным методом. Из диффузионных экспериментов определены значения коэффициентов диффузии катионов изотопа 110mAg в медьсодержащих халькогенидных пленках. Установлено, что значения коэффициентов диффузии ионов Ag+ в химически нанесенных пленках и исходных стеклах практически не различаются. Аналогию значений коэффициентов диффузии изотопа 110mAg в халькогенидных стеклах и пленках на их основе можно объяснить сохранением полимерной сетки связей халькогенидных стекол при их растворении в органических основаниях (аминах). В процессе нанесения и формирования пленок полимерная (макромолекулярная) структура раствора халькогенидных стекол сохраняется. The method of chemical deposition from solutions of chalcogenide glasses in n-butyl amine obtained multicomponent chalcogenide films CuI-As2Se3, CuI-PbI2-As2Se3, CuI-SbI3-As2Se3, CuI-SbI3-PbI2-As2Se3. Synthesis of copper multicomponent chalcogenide glasses, used for film deposition was carried out by vacuum melting in quartz ampoule at a temperature of 400…950 °C and a residual pressure of not more than 0.13 Pa. The temperature of glass produced from the 600 °C to the ice water spill of the melt in the ampoule. Weigh glass comminuted to a powder and heated in n-butylamine until complete dissolution. To prevent oxidation, deposition and annealing of the films was carried out in an atmosphere of nitrogen chemically inert. The substrate is placed on a device for rotating, it was applied to the solution and the substrate was rotated at a speed of several thousand revolutions per minute. Annealing of the films was carried out at 100 °C for 1 hour. Measurement of the electrical conductivity of the obtained films was conducted at a constant current and variable depending on the conductivity values ​​in the temperature range from 20 to 100 °C. Measurement of diffusion coefficients was performed according to the absorption method. From diffusion experiments, the values ​​of the diffusion coefficients 110mAg isotope cations in copper chalcogenide films. It was found that the values ​​of the diffusion coefficients of the ions Ag+ in a chemically deposited films and the original glasses are indistinguishable. The analogy of the diffusion coefficient values ​​110mAg isotope in chalcogenide glasses and films based on them can be attributed to the preservation of the polymer network connections chalcogenide glasses when dissolved in organic bases (amines). During application and film formation the polymer (macromolecular) structure of chalcogenide glasses of the solution is maintained.

Sign in / Sign up

Export Citation Format

Share Document