Electrodeposition of Ni-Mo Defect-Free Alloy from Ammonium-Citrate Electrolyte in Pulse Current Mode

MRS Advances ◽  
2017 ◽  
Vol 2 (58-59) ◽  
pp. 3585-3589
Author(s):  
Sergey M. Karabanov ◽  
Yulia M. Stryuchkova ◽  
Dmitriy V. Suvorov ◽  
Gennadiy P. Gololobov ◽  
Dmitry Yu. Tarabrin ◽  
...  
Keyword(s):  
Pulse Current ◽  
Current Mode ◽  
Density Variation ◽  
Pulse Mode ◽  
Ammonium Citrate ◽  
Molybdenum Alloy ◽  
Nickel Substrate ◽  
Sem Images ◽  
Citrate Electrolyte ◽  
Electrolysis Mode

ABSTRACT Electrodeposition in pulse current mode of nickel-molybdenum alloy on a nickel substrate was studied. The range of current density variation from 2 to 9 A/dm2 was investigated. The range of pulse and pause step lengths is from tens to hundreds of milliseconds. SEM-images of applied coatings surfaces are obtained. The method of energy dispersive spectroscopy determined that the molybdenum content in the coating is 21-24 wt%. It was found that under transient pulse mode of electrolysis, with the pulse step corresponding to hundreds of milliseconds, the most rigid and smooth coatings of the electrolytic nickel-molybdenum alloy are obtained from ammonium-citrate electrolyte. It is shown that the percentage of nickel in the alloy does not depend on the electrolysis mode.

scholarly journals Room Temperature Syntheses of ZnO and Their Structures

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 733
Author(s):  
Domenica Donia ◽  
Elvira Maria Bauer ◽  
Mauro Missori ◽  
Ludovica Roselli ◽  
Daniele Cecchetti ◽  
...  
Keyword(s):  
Room Temperature ◽  
Direct Synthesis ◽  
Threshold Value ◽  
Rietveld Analysis ◽  
Synthesis Temperature ◽  
Density Variation ◽  
Controlled Synthesis ◽  
Sem Images ◽  
Aqueous Solvent ◽  
Average Size

ZnO has many technological applications which largely depend on its properties, which can be tuned by controlled synthesis. Ideally, the most convenient ZnO synthesis is carried out at room temperature in an aqueous solvent. However, the correct temperature values are often loosely defined. In the current paper, we performed the synthesis of ZnO in an aqueous solvent by varying the reaction and drying temperatures by 10 °C steps, and we monitored the synthesis products primarily by XRD). We found out that a simple direct synthesis of ZnO, without additional surfactant, pumping, or freezing, required both a reaction (TP) and a drying (TD) temperature of 40 °C. Higher temperatures also afforded ZnO, but lowering any of the TP or TD below the threshold value resulted either in the achievement of Zn(OH)2 or a mixture of Zn(OH)2/ZnO. A more detailed Rietveld analysis of the ZnO samples revealed a density variation of about 4% (5.44 to 5.68 gcm−3) with the synthesis temperature, and an increase of the nanoparticles’ average size, which was also verified by SEM images. The average size of the ZnO synthesized at TP = TD = 40 °C was 42 nm, as estimated by XRD, and 53 ± 10 nm, as estimated by SEM. For higher synthesis temperatures, they vary between 76 nm and 71 nm (XRD estimate) or 65 ± 12 nm and 69 ± 11 nm (SEM estimate) for TP =50 °C, TD = 40 °C, or TP = TD = 60 °C, respectively. At TP = TD = 30 °C, micrometric structures aggregated in foils are obtained, which segregate nanoparticles of ZnO if TD is raised to 40 °C. The optical properties of ZnO obtained by UV-Vis reflectance spectroscopy indicate a red shift of the band gap by ~0.1 eV.

Electrodeposition of iron–molybdenum alloy from ammonium–citrate solutions and properties of produced materials

2015 ◽  
Vol 51 (8) ◽  
pp. 748-757 ◽  
Author(s):  
V. V. Kuznetsov ◽  
K. E. Golyanin ◽  
Yu. Sh. Ladygina ◽  
T. V. Pshenichkina ◽  
B. F. Lyakhov ◽  
...  
Keyword(s):  
Ammonium Citrate ◽  
Molybdenum Alloy

Study of field electron emission properties of commercial graphite cathodes in pulse-repetitive mode

2020 ◽  
Author(s):  
A.S. Chepusov ◽  
◽  
A.A. Komarskiy ◽  
S.R. Korzhenevskiy ◽  
O.D. Krasniy ◽  
...  
Keyword(s):  
Electron Emission ◽  
Pulse Current ◽  
Current Mode ◽  
Operating Voltage ◽  
Constant Voltage ◽  
Periodic Mode ◽  
Field Emitters ◽  
Pulsed Mode ◽  
Field Emission Cathodes ◽  
Potential Level

The article considers field emission cathodes from industrial graphites MG, MPG-7, and GMZ operated in the pulse-periodic mode with the pulse repetitionrate of 1 to 30 Hz. The operation of field emitters in the pulsed mode differs from operation at a constant voltage. Under stabilization of the high potential level, the amplitude of the pulses of the emission current decreases that leads to increasing the operating voltage in the pulsed mode. During operation of the graphite cathode (when the pulse current is recorded), the operating voltage at the anode stabilizes and oscillates within 5%. Operation in the direct current mode under similar conditions is accompanied by a change in the voltage value by more than 10 %.

Effects of Pulse Current Mode on Plasma Electrolytic Oxidation of 7075 Al in KMnO4Containing Solution

2017 ◽  
Vol 164 (12) ◽  
pp. C690-C698 ◽  
Author(s):  
Reihane Aliramezani ◽  
Keyvan Raeissi ◽  
Monica Santamaria ◽  
Amin Hakimizad
Keyword(s):  
Plasma Electrolytic Oxidation ◽  
Pulse Current ◽  
Current Mode ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic

ACHIEVING A LINEAR DOSE RATE RESPONSE IN PULSE-MODE SILICON PHOTODIODE SCINTILLATION DETECTORS OVER A WIDE RANGE OF EXCITATIONS

2014 ◽  
Vol 27 ◽  
pp. 1460136
Author(s):  
LEWIS CARROLL
Keyword(s):  
Signal Processing ◽  
Dose Rate ◽  
Pulse Generator ◽  
Current Mode ◽  
Pulse Mode ◽  
Radioactive Material ◽  
Activity Levels ◽  
Silicon Photodiode ◽  
Processing Scheme ◽  
Wide Range

We are developing a new dose calibrator for nuclear pharmacies that can measure radioactivity in a vial or syringe without handling it directly or removing it from its transport shield “pig”. The calibrator's detector comprises twin opposing scintillating crystals coupled to Si photodiodes and current-amplifying trans-resistance amplifiers. Such a scheme is inherently linear with respect to dose rate over a wide range of radiation intensities, but accuracy at low activity levels may be impaired, beyond the effects of meager photon statistics, by baseline fluctuation and drift inevitably present in high-gain, current-mode photodiode amplifiers. The work described here is motivated by our desire to enhance accuracy at low excitations while maintaining linearity at high excitations. Thus, we are also evaluating a novel “pulse-mode” analog signal processing scheme that employs a linear threshold discriminator to virtually eliminate baseline fluctuation and drift. We will show the results of a side-by-side comparison of current-mode versus pulse-mode signal processing schemes, including perturbing factors affecting linearity and accuracy at very low and very high excitations. Bench testing over a wide range of excitations is done using a Poisson random pulse generator plus an LED light source to simulate excitations up to ∼106 detected counts per second without the need to handle and store large amounts of radioactive material.

scholarly journals CHARACTERISTICS OF PLASMA ELECTROLYTIC OXIDATION COATINGS ON 6061 AL ALLOY PREPARED AT DIFFERENT CURRENT DENSITIES

2020 ◽  
Vol 58 (6) ◽  
pp. 699
Author(s):  
Quang-Phu Tran ◽  
Van-Da Dao ◽  
Van-Hoi Pham
Keyword(s):  
Plasma Electrolytic Oxidation ◽  
Current Mode ◽  
Coated Sample ◽  
Al Alloy ◽  
Properties Of Coatings ◽  
Sem Images ◽  
Oxide Layers ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
6061 Al Alloy

Plasma electrolytic oxidation (PEO) has earned much attention due to its powerful and easy formation of hard and corrosion-resistant oxide layers on valve metals, such as Al alloys. Here we report the effects of current density (CD) on microstructure and properties of coatings on 6061 Al alloy by PEO using direct current mode. The electrolyte contains the chemicals of Na2SiO3, Na2WO4´2H2O, and NaH2PO2´H2O. The CDs adopted 5.0, 7.5, 10.0, and 12.5 A/dm2, respectively, for a fixed PEO time of 30 min. The thickness, surface morphology, phase composition, hardness, and corrosion resistance of PEO coatings as the function of the applied CD have been studied and discussed. Studied results show the coating thickness is proportional to the applied CD. When the applied CD increases 2.5 times from 5.0 to 12.5 A/dm2, the growth rate of oxide layers increased by more than 3.5 times, from 0.423 to 1.493 μm/min, respectively. SEM images are characterized by a reduction in the ratio of agglomerate-bumps-region/flatten-region as applied CD increases. However, cracks and larger pores appear when the applied CD is higher than 10.0 A/dm2. X-ray diffraction pattern shows that the main phases of Al, g-Al2O3, α-Al2O3, and W are contained in all coatings. PEO coated sample has the highest hardness of 1290 HV and highest polarization resistance of 8.80 ´ 106 Wcm2 obtained at applied CD 10 A/dm2 which shows the best performance of the coating. The variation in coating performance is explained by microstructure details, specifically phases, compositions of oxide-layers, and micro-pores and cracks.

Electrodeposition of a cobalt-molybdenum alloy from an ammonia-citrate electrolyte

2007 ◽  
Vol 43 (3) ◽  
pp. 349-354 ◽  
Author(s):  
V. V. Kuznetsov ◽  
Z. V. Bondarenko ◽  
T. V. Pshenichkina ◽  
N. V. Morozova ◽  
V. N. Kudryavtsev
Keyword(s):  
Molybdenum Alloy ◽  
Citrate Electrolyte
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