Titanium Cathode Research Articles

Producing multilayer composites based on metal-carbon by vacuum ion-plasma method

The possibility of changing the coating properties and perspective of forming a compound having the unique mechanical properties, high hardness and high corrosion resistance is of particular interest to multilayer coatings based on metal-carbon composition. To investigate the mechanisms of formation of coatings and to demonstrate technological possibilities synthesis technology of multilayer composites, the titanium cathode and the silicon-graphite cathode were made. Coatings microhardness analysis showed that in forming the multilayer structure, microhardness increases by 15-20%, and when forming a multilayer composite, microhardness increases by 60-65%.

Electric field induced activated carbon fiber (ACF) cathode transition from an initiator/a promoter into an electrocatalyst in ozonation process

Removal of nitrobenzene (NB), a carcinogenic and refractory pollutant, in aqueous solution by adsorption, ozonation, electrolysis, and electro-peroxone (E-peroxone) with activated carbon fiber (ACF) was investigated, respectively. Kinetic analyses of NB removal by all the processes followed pseudo-first-order kinetics and the Kapp of E-peroxone-ACF was 14.90×10−2min−1, which was much higher than the others. Besides, the Kapp of E-peroxone-ACF process reduces slightly to 12.18×10−2min−1 even after 100 times of ACF recycle, showing a sustainable activity. Moreover, according to the pore texture characteristics, surface functional groups, FTIR, and SEM images, E-peroxone process does not considerably alter the ACF surface, whereas ozone alone can cause substantial damage to it. These results suggested that ACF was induced from an initiator/a promoter into an electrocatalyst in ozonation by free electrons injection. Moreover, comparing with titanium cathode, ACF can remarkably improve the removal of NB in E-peroxone due to the synchronous adsorption of pollutants and ozone as well as the enhancement of H2O2 generation. It indicates that the ACF cathode is a promising material for organic pollutants removal in the E-peroxone process.

Electrokinetic removal of radionuclides contained in scintillation liquids absorbed in soil type Phaeozem

Control samples of scintillation liquids – Phaeozem soil mixtures were prepared with different scintillation liquids as the support electrolyte, Install Gel® XF, (Ultima Gold AB™ and Ultima Gold XR™), to construct the polarization curves, and to select the cell potential with the highest mass transfer to remove 24Na (15 h) and 99mTc (6 h) as radiotracers from polluted Phaeozem soil. During the electrokinetic treatment (EKT), the removal of radionuclides contained in scintillation liquids absorbed in Phaeozem soil, liquid phase was characterized by Gas Chromatography coupled with a Flame Ionization Detector (GC-FID) and Fourier Transform Infrared Spectrometry (FTIR), solids by FTIR, before and after the application of cell potential. In this sense, the support electrolyte was selected based on the highest current generated (1 mA), as in the case of scintillation liquid 50% Ultima Gold XR™ + 50% Water (1:1), which was used for 6 h in the presence of a mesh and a titanium rod, as anode and cathode, respectively. Finally, the removal percentage accumulated in the liquid phase after the EKT of Phaeozem soil polluted by 99mTc was 61% close to the anode after 4 h. It was also 61% for 24Na close to cathode after 2 h, and after 4 h it was 71.8%.

Control of Vacuum Arc Macroparticles by High-Frequency Short-Pulsed Negative Bias Application

Background/Objectives: Paper is devoted to a brief review of the investigation of short negative bias pulse application for titanium and aluminum macroparticles control on the substrate immersed in vacuum arc plasma. Methods/Statistical Analysis: The vacuum-arc plasma generator with a titanium or aluminum cathode which operated in a DC mode with the arc current 100 A was set on the side flange of the vacuum chamber. A high-frequency short-pulse negative bias generator was used to carry out the investigations. The parameters of the generator are: pulse duration 1–9 μs, pulse repetition rates 105 pulse per second (p.p.s.), negative pulse amplitude 0.5–3.5 kV. The MP densities on the substrate surface were studied using optical and electron (Hitachi TM–1000 and Hitachi TM–S 3400 N) microscopes. Findings: It was found that the decreasing of MP surface number density on a negatively biased substrate is determined by the pulse amplitude, pulse duration, pulse frequency, plasma density and processing time. A possibility to reduce the macroparticle number density more than 1000 fold has been demonstrated. Applications/Improvements: The application of high voltage highfrequency short-pulse negative bias to a substrate immersed in vacuum arc plasma provides the possibility of the multiple decrease of MP number surface density and opens a possibility for realization plasma immersion metal ion implantation technology using DC vacuum arc plasma.

Electrochemical Degradation of Acid Yellow 23 by Anodic Oxidation—Optimization of Operating Parameters

In this study, the electrochemical oxidation (EO) process was implemented and optimized to effectively decolorize and degrade wastewater containing Acid Yellow 23 (Y23). The experiments were carried out in a laboratory-scale batch cell reactor, with monopolar configuration of electrodes, made of graphite (anode) and titanium (cathode). The response surface methodology (RSM), coupled with Box-Behnken experimental design (BBD), was used to evaluate the single and interactive effects of different variables of the EO process on (1) degradation percentages of both chemical oxygen demand (%DCOD) and color (%DC) and (2) energy consumption (EC). Thus, the following experimental factors were considered: initial dye concentration (40–100 mg/L), current density (10–20 mA/cm2), and conductivity (1,000–4,000 μS/cm). Thus, the subsequent conditions were found to be optimal for decolorization and degradation of Y23: initial dye concentration = 100 mg/L; current density = 20 mA/cm2; and conductivity = 4,000 μS/cm. At these conditions, the EO process allowed to reach approximately 99% of color degradation and 76% of COD degradation. Because NaCl was used as an electrolyte, chorine formation was monitored, and its effect on %DC and %DCOD was also evaluated.

Effects of electrode gap and electric potential on chlorine generation of electrolyzed deep ocean water

Electrolyzed water is a sustainable disinfectant, which can comply with food safety regulations and is environmentally friendly. A two-factor central composite design was adopted for studying the effects of electrode gap and electric potential on chlorine generation efficiency of electrolyzed deep ocean water. Deep ocean water was electrolyzed in a glass electrolyzing cell equipped with platinum-plated titanium anode and cathode. Results showed high electric efficiency at a low cell potential, and a high current density and high chlorine concentration at a high cell potential and low electrode gap. Current efficiency of the system was not significantly affected by electrode gap and electric potential. A small electrode gap reduced the required cell potential and resulted in high energy efficiency. The optimal choice of electrode gap and cell potential depends on the chlorine level of the electrolyzed deep ocean water to be produced, and a small electrode gap is preferred.

Effect of Substrate Nature and Electrolysis Modes on Ultramicron and Nanosized Electrolytic Powders Formation Regularities

This article presents the research on the effect of substrate nature and electrolysis modes on ultramicron and nanosized electrolytic powders formation regularities. It was found that the preliminarily electropolishing of titanium cathode in combination with impulse electrolysis mode for nickel and copper powders obtaining provides for the predomination of nanosized fraction. The presence of water soluble polymers in the electrolyte for copper powder obtaining, polyvinylpyrrolidone (PVP) and polyacrilamide (PAA) allows forming stable dendritic powders with low agglomeration. Using of powders stabilized by polymers allows obtaining compositions with uniform particle distribution across the whole volume of the sample which provides for heightened wear resistance of composition materials.

Anti-corrosion Wear-resistant Coatings on Parts of Oil Field Equipment

The paper reports on the preparation of ion-plasma anti-corrosion and wear-resistant coatings Cr-Mn-Si-Cu-Fe-Al and Cr-Mn-Si-Cu-Fe-Al-Ti. The first coating is prepared using the composite cathode. The second coating is prepared by simultaneous sputtering of composite and titanium cathodes in nitrogen atmosphere. In both cases the cellular microstructure of coatings is observed. The nanohardness of coating Cr-Mn-Si-Cu-Fe-Al, which is 7.4GPa, is nearly two times as high as the nanohardness of titanium being 4.1GPa and almost the same as for multilayer film Ti/α-C:Н which is 8.0GPa. The corrosion rate in sulfuric acid (53wt.%) is about 0.02mm/year. The nanohardness of coating Cr-Mn-Si-Cu-Fe-Al+Ti, being 14.2GPa, is nearly equal to the nanohardness of amorphous ribbon Zr-Cu-Ti-Ni, being 14.5GPa or silicon (100), which is 14.8GPa. The corrosion rate in sulfuric acid (53wt.%) is less than 0.01mm/year. The multilayer film of Ti/α-C:Н and amorphous tape Zr-Cu-Ti-Ni are used as abrasives, but their preparation is ten times more expensive than the proposed coatings.

Modulating the degradation behaviour of iron-based alloys by grain-sizing and alloying

Event Abstract Back to Event Modulating the degradation behaviour of iron-based alloys by grain-sizing and alloying Agung Purnama1, 2, Camillus Sunday Obayi1, 3, Ranna Tolouei1, Essowe Mouzou1, Carlo Paternoster1, Malgorzata Sikora-Jasinska1, 4, Hendra Hermawan1 and Diego Mantovani1 1 CHU de Québec Research Center, Laval University, Lab. Biomaterials and Bioengineering, CRC-I, Dept Min-Met-Materials Eng, Canada 2 Politecnico di Milano, Laboratory for Laser Application, Department of Mechanical Engineering, Italy 3 University of Nigeria, Department of Metallurgical & Materials Engineering, Nigeria 4 Politecnico di Milano, Department of Mechanical Engineering, Italy Iron-based alloys have been reported previously as biodegradable metals for cardiovascular stent applications due to their biocompatibility and comparable mechanical properties to those of stainless steel[1]. Iron has been alloyed principally with manganese[2] and addition of other minor elements such as palladium[3], carbon[4], and silicon[5] to tailor its strength and degradation rate that match tissue-healing process. New fabrication techniques such as powder metallurgy[2], electroforming[6], and magnetron sputtering[7] have been reported for the same objectives. Despite all the approaches taken to enhance the degradation rate of iron-based alloys, there are limited studies focused on the factors that influence their degradation rate. It was previously reported that the change of grain size influenced the degradation behaviour of pure iron since superior number of grain provides higher density of matrix and grain boundary where corrosion reaction takes place[1],[6]. Therefore, the objective of the current study is to investigate the effect of grain sizes towards the corrosion behaviour of pure iron. In order to do so, pure iron sheets (Armco soft ingot, purity >99.8%, Goodfellow, UK) with various grain sizes were produced by thermomechanical treatments comprising cold rolling (75-85% thickness reduction) and annealing (550oC-1000oC). The resulting sheets composed of pure iron sheets with grain size varied from 14 um to 168 um with degradation rate between 0.20 to 0.24 mmpy. In the effort of producing iron sheet with grain size smaller than 14 um, electrodeposition of pure iron on titanium cathode was used resulting iron sheet (99.7% purity) with the average grain size of 6 um following annealing at 550oC. The results showed that smaller grain size iron sheet produced by electrodeposition exhibited superior degradation rate (0.51 mmpy) compared to those of the iron sheets with modified grain size by thermo-mechanical treatments. Moreover, it showed superior mechanical properties (YS=270MPa, UTS=292MPa) compromising its elongation at break (e=18.4%) when compared to other iron sheets. Additionally, when manganese was added (35%wt.) to enhance the degradation behaviour of pure iron by powder metallurgy, it gave average grain size of 50 um with degradation rate close to that of electrodeposited iron. The results suggested that the grain size influences the degradation rate of pure iron. Specific window of grain size was observed, in which the degradation rate of pure iron decreased along with the reduction of the grain size (range 10-160 um of grain size). Moreover, alloying was observed to excite the degradation rate of pure iron since in the range where degradation rate of pure iron was low. Suggestively, manganese as the alloying element contributes to the galvanic corrosion process that accelerates the degradation rate of pure iron. This study provides evidence in different approaches to modulate the degradation behaviour of iron-based alloys by changing the grain size and alloying technique. This work was partially supported by NSERC-Canada, CIHR-Canada, CFI-Canada, FRQ-NT-Quebec, and MRI-Quebec. The authors would like to acknowledge the prestigious NSERC Post Doctoral Fellowship (NSERC-PDF) awarded to Agung Purnama; Commonwealth Scholarship Program (Government of Canada) and University of Nigeria for scholarship award to CSO for the scholarship of Camillus Sunday Obayi; ACDI and AUCC for providing scholarship to Essowè Mouzou.

Antifriction Superhard Coatings for Drill Bits and Boring Cutters

Coatings obtained by sputtering a stainless steel cathode and a plate titanium cathode cut from drill bit cutters JCS-M60 MX 172 544.00 are investigated. The measured microhardness of the plate drill bit is 1400 HV (Vickers) and that of coating 12Cr18Ni10T+Ti is 2200 HV that is significantly higher. The measured coefficient of dry friction for a drill bit plate on steel equals to 0.82, and it is 0.12 for coating 12Cr18Ni10Ti+Ti. Coating 12Cr18Ni10Ti+Ti deposited on the drill bit cutters in nitrogen gas may be used to modify the surface of drill bits and boring cutters to increase their lifetime. Such coatings, having a small friction coefficient, high hardness and low cost of production, can compete with traditionally used diamond materials.

Fine-tunable micro-patterns in Chitosan-based scaffolds: fabrication process and material properties

Fine-tunable micro-patterns in Chitosan-based scaffolds: fabrication process and material properties

Electrochemical conversion of CO2 to carbon and oxygen in LiCl–Li2O melts

Carbon dioxide was electrochemically decomposed to carbon and oxygen gas in molten LiCl–5.0wt.% Li2O molten salts at 903K using a titanium cathode and inert platinum anode. CO2 chemically dissolves into the LiCl–Li2O melt by reacting with Li2O, changing the electrolyte LiCl–Li2O–CO2 into Li2CO3 and LiCl. Carbonate anions are electrochemically reduced to carbon on the cathode, while oxygen complexes of carbonate anions are oxidized at the anode, generating O2. Electrolysis of the LiCl–5.0wt.% Li2O molten salt under a CO2 atmosphere at 0.05A/cm2 yields anodic gas with a CO2/O2 ratio of 0.42. The CO2/O2 ratio increases with increasing current density. The proposed concept may provide oxygen and fuel supplies to future explorers and inhabitants of Mars.

Dovetail Tip: A New Approach for Low-Threshold Vacuum Nanoelectronics

An innovative approach for the fabrication of low-threshold, nanoscale field-emitter cathodes and arrays is proposed. By shaping a titanium cathode as dovetail geometry and using a thin vertical wall of high-permittivity dielectric, Si3N4, to isolate the tip from the gate, the electric field intensity near the tip edges is strongly increased, and a turn-ON voltage in the range of a few volts is predicted numerically and observed experimentally. The resulting cathode structure is compact, self-aligned to the vacuum cavity and is fabricated through the standard silicon fabrication processes. Besides, unlike all existing approaches, vacuum is achieved at the wafer level and not at the package level, thereby reducing fabrication costs. Measurements on a first prototyped array of $5\times 4$ diode-connected parallel devices with a silicon area of $5~\mu \text {m}\times 4~\mu \text{m}$ , confirm Fowler–Nordheim emission with a 2 V turn-ON voltage, while displaying a total emission current of 25 $\mu \text{A}$ at a gate-cathode bias of 20 V.

Control of Structure and Properties of Nanostructured Multilayer Composite Coatings Applied to Cutting Tools as a Way to Improve Efficiency of Technological Cutting Operations

The study considers the challenge of improving the efficiency of dry finishing and semi-finishing turning of (P10-P20) steel with carbide tools with complex composition coatings by directed selection of the composition and properties of the coatings through the control of the parameters of the filtered cathodic vacuum-arc deposition (FCVAD). The conducted tests have confirmed the feasibility and effectiveness of the control of compositions, structures, and properties of complex composite coatings of Ti-TiN-TiAlN type by varying the parameters of the FCVAD process. In particular, it has been found out that the ratio of Ti/Al, which greatly affects the important properties of the coating (grain size, lattice parameter, microhardness, fracture toughness, etc.), can be changed at constant compositions of cathodes by varying such parameters of coating synthesis as titanium cathode arc current, nitrogen pressure, and substrate shear stress. It has been shown that Ti-TiN-TiAlN coating produced at different values of the parameters of synthesis significantly changes the cutting properties of carbide tool and thus allows optimizing the coating composition for a variety of machining conditions.The developed methods are also applicable for multi-component complex composite coatings.

Rotational and gas temperatures of molecular deuterium in a hollow cathode glow discharge

Abstract We report the results of optical emission spectroscopy measurements of rotational Trot and translational (gas) temperature of deuterium molecules. The light source was a low-voltage high-pressure hollow cathode (HC) glow discharge with titanium cathode operated in deuterium. The rotational temperature of excited electronic states of D2 was determined from the intensity distribution in the rotational structure of Q-branches of the two Fulcher-α diagonal bands: [ν′ = ν″ = 2] and [ν′ =ν″ = 3]. The population of the excited energy levels, determined from relative line intensities, was used to derive the radial distributions of the temperature of the excited and the ground state of the deuterium molecule.

Growth of microscopic cones on titanium cathodes of sputter-ion pumps driven by sorption of large argon quantities

Microscopic cones have been observed on titanium cathodes of sputter-ion pumps (SIPs) after pump operation. The cones were studied by means of scanning electron microscopy and energy dispersive x-ray analysis. Size and morphology of these cones are clearly correlated with the nature and the relative amount of each gas species pumped by each SIP during its working life. In particular, their growth was found to be fed by sputtering mechanisms, mostly during Ar pumping, and to be driven by the electromagnetic field applied to the Penning cells of each SIP. Experimental findings suggest that the formation and extent of such conic structures on cathode surfaces might play a leading role in the onset of phenomena typically related to the functioning of SIPs, e.g., the so-called argon instability.

XPS study of TiN films formed by the electric arc technique

The phase composition of the 3 nm surface layer of Ti and TiN films is studied by X-ray photo-electron spectroscopy. The films are deposited by the electric arc sputtering of a titanium cathode in a nitrogen atmosphere under a magnetic field. It is shown that the film surface layer contains TiN, TiN x , TiO x , TiO2, and TiN x O y phases. A mechanism explaining the formation of titanium nitride films is proposed.

Improving the wear resistance of tungsten-carbide hard alloys

The influence of zirconium in the (Ti, Zr)N ion-plasma coating on VK10KS alloy is studied. The (Ti, Zr)N ion-plasma coating is applied by means of a Kvant-6 instrument, using separate titanium and zirconium cathodes so as to obtain the composition 50% Ti + 50% Zr; nitrogen is used as the reaction gas. In that case, the two titanium-alloy cathodes are opposite one another within the instrument, while the zirconium-alloy cathode is between them. The introduction of zirconium in the (Ti, Zr)N coating increases its nanohardness to 38500 MPa (by 23%) and the Young’s modulus by 67%. That indicates increase in the binding energy of the atoms and the strength of the coating. In addition, we observe increase in wear resistance and decrease in the coating’s frictional coefficient to 0.07, while its adhesive strength is satisfactory. In other words, the performance of the whole hard alloy is improved.

Enhanced Photoelectrocatalytic Decomposition of Copper Cyanide Complexes and Simultaneous Recovery of Copper with a Bi2MoO6 Electrode under Visible Light by EDTA/K4P2O7

Simultaneous photoelectrocatalytic (PEC) oxidation of cyanides and recovery of copper in a PEC reactor with a Bi(2)MoO(6) photoanode was investigated at alkaline conditions under visible light irradiation. The surface variation of the Bi(2)MoO(6) photoanode and titanium cathode was characterized. The Cu mass distribution onto the anode, in the solution, and onto the cathode was fully investigated. In the individual PEC oxidation of copper cyanides, the formation of a black copper oxide on the anode occurred. By keeping the initial cyanide concentration at 0.01 mM, the effect of EDTA/K(4)P(2)O(7) was examined at different molar ratios of EDTA/K(4)P(2)O(7) to cyanide. It was indicated that the oxidation of cyanides increased and simultaneous copper electrodeposition with zero value onto the cathode was feasible at pH 11. Under the optimal conditions, the total cyanide concentration was lowered from 250 to 5.0 mg/L, and the Cu recovery efficiency deposited onto the cathode was higher than 90%. Cyanate was the only product. The role of the photogenerated hole in the oxidation of cyanide ions was confirmed.

Low-voltage electric field applied into MBR for fouling suppression: Performance and mechanisms

A low-voltage electro-membrane bioreactor (e-MBR) for fouling alleviation was designed using stainless steel anodes and a membrane module containing titanium cathodes (Fe-MBR). The electric field was applied intermittently once the suction pump was stopped. Compared with another e-MBR with titanium anodes (Ti-MBR) and with one MBR without an electric field, the Fe-MBR had lower transmembrane pressure (TMP), less irreversible fouling and higher pollutant removals under an intermittent voltage of 2.72V and current of 0.1A. Coagulation was not obvious because no significant changes were observed in either particle size or zeta potential. The electric field induced backwash was confirmed, by the Ti-MBR, to be effective to suppress fouling. The electric field force might prevent the tight precipitation of foulant on the membrane’s surface and make the fouling layers looser and easier to be removed by aeration. Besides, a strong positive correlation was obtained between fouling indexes and total organic carbon of soluble microbial products (SMPs), suggesting that the reduction of SMPs in the Fe-MBR could have resulted in the fouling depression, and was related to the release of iron. Thus, the joint effects of the electric field force and the release of iron deducted foulant and irreversible fouling, and ultimately lessened the overall fouling. The energy consumption estimation showed 10% more electricity was consumed to make TMP reduce by 30%, indicating the Fe-MBR would be promising in application.