Mixture Of Graphite Powder Research Articles

Wear-Resistant Low-friction Atmospheric Pressure Plasma Spray Coatings for Sustainable (Bio-based Recyclable) Materials

Coatings from polyetheretherketone (PEEK), polyamide 12 (PA12), molybdenumdisulfide (MoS2), zinc (Zn), and graphite (C) powder mixtures were deposited on PA6, PA12, and PEEK substrates by an atmospheric pressure plasma (APP) spray jet system. Several tenth of µm thick coatings on PA6 and PA12 substrates result in an almost halved surface roughness Ra ~8 µm, Rq ~10 µm and Rz ~60 µm, whereas a significant increase of all surface roughness parameters is observed for PEEK substrates (Ra < 1 µm → 4 µm, Rq < 1 µm → 5 µm, Rz < 5 µm → 20 µm). The surface roughness, powder composition, and selected APP process parameter strongly influence the coefficient of friction (COF) and specific wear rate ki of the APP coatings in rotational ball-on-disc tribological testing. The COF of PA12/MoS2/C coatings on PA6 substrates manufactured by selective laser sintering (SLS) is ~0.2 after 628 m sliding distance, resulting in a very low calculated ki of 6.3 × 10−7 mm3/Nm. A similarly low COF and ki was observed for PEEK coatings deposited at a current of 75 A and 60 mm jet–substrate distance on SLS PA12 substrate. Although the COF of Zn/C/MoS2 coatings on PEEK drops down below 0.1 after 1884 m sliding distance under nitrogen atmosphere the corresponding ki of 5.6 × 10−5 mm3/Nm is higher. Still all calculated specific wear rates are significantly lower than the reported values of polyamide-polytetrafluorethylene (PTFE)-polyethylene composites (1.9–8.0 × 10−2 mm3/Nm) and partly even outperform PEEK-PTFE composites (1.0 × 10−7–2.5 × 10−6), currently applied in demanding wear regimes.

High thermal conductivity of porous graphite/paraffin composite phase change material with 3D porous graphite foam

Phase change materials (PCMs) are widely used in the field of thermal management and energy storage, but both low thermal conductivity and leakage problem limit their broad applications. In this work, a 3D porous graphite (PG) foam was prepared by a pressing and drying method with solid mixture of graphite powder and ammonium bicarbonate (NH4HCO3), and it was used as the thermal conductive skeleton and shape stabilizer of PCMs. PG/paraffin composite PCMs (CPCMs) were then prepared by the vacuum impregnation of liquid paraffin into PG foam. It showed that the skeleton of 3D PG foam greatly improves the thermal conductivity of CPCMs. The prepared PG/paraffin CPCMs exhibited an ultra-high thermal conductivity of 19.27 Wm-1K−1 at a volume fraction 35.55% of graphite, which is about 76.08 times higher than that of paraffin. The heat conduction mechanism of the PG/paraffin CPCMs are analyzed, and it is found that Maxwell-Eucken model can be used to accurately predict its thermal conductivity. Moreover, the CPCMs show good performance of thermal shape stability and exhibit superior anti-leakage characteristic. The proposed method for the preparation of 3D PG foam is robust, and the excellent performance of their based CPCMs will be promising in the field of heat dissipation and thermal storage.

Development of an anatomical breast phantom from polyvinyl chloride plastisol with lesions of various shape, elasticity and echogenicity for teaching ultrasound examination.

The WHO reported an increasing trend in the number of new cases of breast cancer, making it the most prevalent cancer in the world. This fact necessitates the availability of highly qualified ultrasonographers, which can be achieved by the widespread implementation of training phantoms. The goal of the present work is to develop and test an inexpensive, accessible, and reproducible technology for creating an anatomical breast phantom for practicing ultrasound diagnostic skills in grayscale and elastography imaging, as well as ultrasound-guided biopsy sampling. We used FDM 3D printer and PLA plastic for printing an anatomical breast mold. We made a phantom using a mixture of polyvinyl chloride plastisol, graphite powder, and metallic glitter to simulate soft tissues and lesions. Various degrees of elasticity were imparted using plastisols of stiffness ranging from 3 to 17 on the Shore scale. The lesions were shaped by hand. The materials and methods used are easily accessible and reproducible. Using the proposed technology, we have developed and tested a basic, differential, and elastographic versions of the breast phantom. The three versions of the phantom are anatomical and intended for use in medical education: the basic version is for practicing primary hand-eye coordination skills; the differential one is for practicing the differential diagnosis skills; the elastographic version helps developing the skills needed for assessing the stiffness of tissues. The proposed technology allows the creation of breast phantoms for practicing hand-eye coordination and develop the critical skills for navigation and assessment of the shape, margins, and size of the lesion, as well as performing an ultrasound-guided biopsy. It is cost-effective, reproducible, and easily implementable, and could be instrumental in generating ultrasonographers with crucial skills for accurate diagnosis of breast cancer, especially in low-resource settings.

Two-dimensional ruthenium nanoparticles between graphite layers: The effect of reduction temperature

A mixture of graphite powder and ruthenium chloride (III) anhydrous was treated at 723 K under 0.3 MPa chlorine for 3 days, followed by reduction under 40 kPa of hydrogen for 1 h to produce ruthenium metal particles intercalated between graphite layers (Ru-GIC). The structures of ruthenium particles depended on the reduction temperatures. Sheet-like ruthenium particles with 1–3 nm thickness and 10 to several hundred nm width containing numerous irregularly shaped holes with round edge, were formed by reduction at 573 K. A Ru-GIC sample treated at 653 K possessed two-dimensional ruthenium nanosheets with hexagonal holes (straight lines intersect at an angle of 120°) in a similar range of thickness and width. On the other hand, Ru-GIC samples reduced at 773 and 823 K showed two-dimensional plate morphology with a thickness of 1–4 nm. In addition, ruthenium nanoparticles supported on the graphite surface (Ru/Gmix) were also prepared from a slurry of ruthenium chloride (III) hydrate and graphite powder by impregnation and hydrogen reduction. The ruthenium particles in Ru/Gmix were spherical at about 3.6 nm, and the reduction temperature did not affect their particles size. Both Ru-GIC and Ru/Gmix samples were evaluated for cinnamaldehyde (CAL) hydrogenation in supercritical carbon dioxide solvent at 323 K, and they were active to produce cinnamyl alcohol (COL) and hydrocinnamaldehyde (HAL). However, Ru-GIC samples showed higher COL selectivity than Ru/Gmix prepared at the same reduction temperature, and COL selectivity over Ru-GIC increased with the reduction treatments at 773 and 823 K.

Microstructural and sensor data analysis of friction stir processing in fabricating Al6061 surface composites

Aluminium alloys, having high strength, ductility, and toughness, are useful structural materials. Composites of these with ceramic reinforcements improve the hardness and wear-resistance, making them suitable for use in the aerospace and automobile industries. Since surface properties play a crucial role for most applications, the manufacturing of surface composites of aluminum alloys is recommended. For this purpose, friction stir processing (FSP) is being utilized nowadays. It refines the microstructure with a homogeneous dispersion of reinforcements into the matrix and improves physical characteristics like surface hardness, wear resistance, strength, etc, while retaining the original characteristics of remaining volume. The study aims to investigate and compare the temperature and vibration sensor data while manufacturing Al6061 surface hybrid composites by using FSP tools with different geometries. The FSP method is utilised for the fabrication of the composites with the copper and graphite powders mixture (1:1), reinforced into the matrix surface by using two H13 tools with two different pin profiles - threaded cylindrical and plain cylindrical. Holes of different diameters and depths are drilled on the Al6061 matrix for reinforcement addition. This FSP process is investigated using a thermal gun and a Cross-Domain Development kit for temperature and vibration measurement. The variation in the vibration signals occurring on the composite workpiece during the entire process with the temperature measurements at equal intervals, is obtained. It is found that both the temperature and vibration amplitudes (400 °C and 1111Hz) are lower in the composites fabricated by FSP tool with threaded pin profile than that by FSP tool with plain pin profile (455 °C and 1305 Hz). Also, the processed samples are investigated for the microstructure by Field Emission Scanning Electron Microscope and Energy-Dispersive x-ray Spectroscopy tests. It is found that the reinforcements are dispersed more uniformly and much reduced in size (0.5482 μm) when prepared by the FSP tool with threaded cylindrical pin, while these particles are heterogeneously dispersed and less reduced in size (1.11 μm) when processes by the FSP tool with plain cylindrical pin. This research can be used to further monitor and control properties like temperature, vibration, force, current, etc, to obtain a uniform reinforcement dispersion with improved mechanical properties during the surface composite preparation by FSP.

Preparation of carbon-based quantum dots and metal nanocomposites and their applications in sensors

Carbon-based quantum dots, zero-dimensional carbon nanomaterials that can be widely used with a particle size of 1-10nm, can be widely used in fluorescent carbon nanomaterials in thousands of households. This article will first elaborate on carbon-based quantum dots and metal nanomaterials and explain the related methods of making them. First, the top-down method is used to prepare carbon quantum dots, the fluorescence mechanism of carbon-based quantum dots is used, and the electrochemical method is used at high temperature. Carbonization burning method and laser ablation method, the mixture of graphite powder and polyethylene glycol ester is hot pressed, baked, and cut in an argon atmosphere to obtain strong fluorescent carbon-based quantum dots, and then explain the immune algorithm to prepare nanocomposites for cermet mold materials, use the diversity of antibodies to calculate the concentration and quantity, and calculate its viability. Through regression coefficients, it can be shown that the immune algorithm is used to optimize the component optimization design of Ti(C,N)-based nanocomposite cermet mold materials. The effect is better.

Quantitative Analysis of Pb(II) Based on Differential Pulse Anodic Stripping Voltammetry and IIP-Carbon Paste Electrodes

It is well known that Pb(II) is considered a highly toxic metal. The slight difference between toxic and permissible levels in drinking water is a matter of concern; therefore, highly sensitive and selective techniques have been proposed for quantification, such as the electrochemical ones. In this work, an easy, simple, low-cost, and high selective sensor based on carbon paste electrodes (CPE) and ion-imprinted polymers (IIP) is proposed for Pb(II) analysis in real water samples. Recognition cavities, selective to Pb(II), were synthesized based on a cross-linked polymer using vinyl pyridine. A modified CPE was constructed by a mixture of graphite powder, IIP, and paraffin oil. By voltammetry studies, a notable difference was observed in the electrochemical response of the electrodes modified with IIP and those with non-imprinted polymer (NIP), confirming the existence of the recognition cavities in the IIP. The construction and analysis parameters related to the analytical response of Pb(II) (anodic current intensity of stripping voltammetry), were optimized; the selectivity was also studied considering potential interference ions. A linear concentration range from 3.3 mg l−1 to 33 mg l−1 and a limit of detection of 0.99 mg l−1 were achieved. Pb(II) was successfully quantified in real complex samples without previous treatment.

Generation of Si@C/SiC@C core–shell nanoparticles by laser irradiation of silicon grinding waste

AbstractIn recent years, the demand for lithium‐ion batteries has increased because of the global focus on carbon neutrality. Silicon/carbon (Si/C) composite nanoparticles have potential for application as high‐performance anode materials in lithium‐ion batteries, which can enable the widespread use of lithium‐ion batteries or lithium‐ion capacitors and contribute toward decarbonized society. In this study, Si@C/SiC@C core–shell nanoparticles with sizes in the range of 10–40 nm were produced by pulsed laser irradiation (wavelength = 1070 nm; pulse width = 10 ms) of a mixture of graphite powder and waste Si powder discharged from the grinding process of Si wafers. High‐speed camera observations of the laser‐induced plume were conducted to elucidate the nanoparticle generation mechanism, and it was determined that Si/SiC nanoparticles were formed within the laser‐induced plume in the early stage of laser irradiation. Si and C demonstrated different plume propagation patterns and plume decay times, and the time difference enabled the coating of the generated Si/SiC nanoparticles with a thin layer of graphene, forming core–shell hybrid structures. The electron diffraction results revealed that the generated nanoparticles were mainly composed of 3C‐SiC@C core shells, which is a novel nanomaterial with promising applications as anode materials for future lithium‐ion batteries.

Composite Graphite-Epoxy Electrodes for In Situ Electrochemistry Coupling with High Resolution NMR.

The in situ coupling between electrochemistry and spectrometric techniques can help in the identification and quantification of the compounds produced and consumed during electrochemical reactions. The combination of electrochemistry with nuclear magnetic resonance is quite attractive in this respect, but it has some challenges to be addressed, namely, the reduction in the quality of the NMR signal when the metallic electrodes are placed close to or in the detection region. Since NMR is not a passive technique, the convective effect of the magnetic force (magnetoelectrolysis), which acts by mixing the solution and increasing the mass transport, has to be considered. In seeking to solve the aforementioned problems, we developed a system of miniaturized electrodes inside a 5 mm NMR tube (outer diameter); the working and counter electrodes were prepared with a mixture of graphite powder and epoxy resin. To investigate the performance of the electrodes, the benzoquinone reduction to hydroquinone and the isopropanol oxidation to acetone were monitored. To monitor the alcohol oxidation reaction, the composite graphite–epoxy electrode (CGEE) surface was modified through platinization. The electrode was efficient for in situ monitoring of the aforementioned reactions, when positioned 1 mm above the detection region of the NMR spectrometer. The magnetoelectrolysis effect acts by stirring the solution and increases the reaction rate of the reduction of benzoquinone, because this reaction is limited by mass transport, while no effect on the reaction rate is observed for the isopropanol oxidation reaction.

Simulation of Variable Magnetic Field Effect on Natural Convection Heat Transfer of Fe3O4/Graphite Slurry based on Experimental Properties of Slurries

Natural convective heat transfer of Fe3O4/graphite slurry in a square cavity is numerically examined. The slurry is assumed to be a non-Newtonian ferrofluid under a variable external magnetic field. The left and right walls of the cavity are assumed to be at a relatively low temperature (Tc), while the horizontal walls are thermally insulated. A heat source with a variable temperature distribution is located at the bottom of the enclosure. The non-Newtonian behavior of the graphite slurry (a mixture of ethylene glycol and graphite powder) has been modelled using experimental results. The control volume method and the SIMPLE algorithm were used to discretize and solve the governing equations considering the Ferro-hydrodynamics (FHD), the Magnetohydrodynamics (MHD) and the non-Newtonian fluid behavior. The heat transfer and fluid flow properties are determined for different locations of the magnetic field source, and different values of the magnetic number (Kelvin force), and the Hartmann number (Lorentz force). The results show that when the magnetic field source is located below the enclosure and near the heat source, the vortices are strengthened resulting in an increased heat transfer. The heat transfer rate is affected by FHD and MHD. When the magnetic field source is located at the corner points, the heat transfer rate is not significantly affected by the magnetic and Hartmann numbers. However, once the magnetic field source is located near the central point of the lower wall of the enclosure, the heat transfer rate is influenced by the increase of the magnetic number.

Use of powder bath sintering for the fabrication of hard ceramic tools

ABSTRACT This article investigates the effect of ceramic powder bath heat-treatment on the sintering of α-alumina (α-Al2O3) for potential ceramic tool application. Three different ceramic sintering mediums were used i.e., (i) Pure alumina powder bath, (ii) Pure graphite powder bath, and (iii) Alumina Graphite Powder Bath (AGPB). The hardness and microstructural analysis were carried out using Vickers hardness, Field Emission Scanning Electron Microscopy (FESEM), and Scanning Electron Microscopy (SEM). The experimental results revealed that the novel Alumina Graphite Powder Bath (AGPB) sintering mechanism proposed in this research provided better hardness and microstructure as compared to the rest. The heating mechanism of alumina and graphite powder mixture was compared with published Thermogravimetric analysis (TGA) results. The Alumina Graphite Powder Bath (AGPB) sintering method improved the mean hardness and relative density by 23% and 13%, respectively. Further, an orderly crystalline corundum microstructure with closed porosity was revealed from Scanning Electron Microscopy (SEM) micrographs. The conversion of convection-radiation to conduction mode of heat transfer in Alumina Graphite Powder Bath (AGPB) sintering technique was the reason behind this property enhancement.

Platinum Nanosheets Intercalated into Natural and Artificial Graphite Powders.

Insertion of sheet-type platinum particles (platinum nanosheets) between graphite layers was achieved by a thermal treatment of a mixture of platinum chloride (IV) and graphite powder (natural graphite or artificial graphite) under 0.3 MPa of chlorine at 723 K, followed by the treatment under 40 kPa of hydrogen pressure. Similar platinum nanosheets, which were 1-3 nm in thickness and 100-500 nm in width and had a number of hexagonal holes and edges with 120° angle, were formed between the layers of both natural graphite or artificial graphite; however, their location in the graphite layers depended on the type of graphite used. A number of platinum nanosheets were observed in the edge region of natural graphite particles which have flat surface. On the other hand, a number of platinum nanosheets were found inside and away from the edge of the artificial graphite particles especially in the vicinity of the cracks. Both the platinum nanosheet-containing artificial and natural graphite samples showed high selectivity to cinnamyl alcohol in cinnamaldehyde hydrogenation under supercritical carbon dioxide conditions, while spherical platinum particles, which were located on the surface of natural and artificial graphite, showed lower selectivity.

Brick-Shaped Antenna Module for Microwave Brain Imaging Systems

In this letter, we describe and validate a microwave antenna designed for an imaging device for the diagnosis and monitoring of cerebrovascular pathologies. The antenna consists of a printed monopole immersed in a parallelepipedic block of semiflexible material with custom-permittivity, which allows to avoid the use of liquid coupling media and enables a simple array arrangement. The “brick” is built with a mixture of urethane rubber and graphite powder. The $-$ 10 dB frequency band of the antenna is 800 MHz—1.2 GHz, in agreement with the device requirements. The designed brick antenna is assessed in terms of power penetration, reflection, and transmission coefficients. To show the performance of the antenna in the relevant application scenario, an experiment has been carried out on an anthropomorphic head phantom, measuring the differential signals between healthy state and hemorrhagic stroke mimicking condition for different antennas positions.

A lab-made screen-printed electrode as a platform to study the effect of the size and functionalization of carbon nanotubes on the voltammetric determination of caffeic acid

This study describes the fabrication of carbon screen-printed electrodes (SPEs) from alternative and low-cost materials. The carbon conductive ink was prepared from a mixture of graphite powder and colorless nail polish. To produce the SPEs, the ink was spread on polyester overhead projector sheets, which acted as a flexible and water-impermeable substrate. To improve the analytical performance, the SPEs were chemically modified with multiwalled carbon nanotubes (MWCNTs) by a simple drop-casting procedure. The effects of the acidic functionalization and size of the MWCNTs on the electrochemical behavior of the SPEs were evaluated. As a proof of concept, the MWCNT/SPEs were applied to determine caffeic acid (CA) in tea samples. CA is a biologically important molecule with antioxidant activity and several beneficial effects on human health, therefore its determination in food and beverages is relevant. The SPEs modified with the acidic-functionalized longer diameter MWCNTs presented the broadest linear range for CA, from 2.0 µmol L−1 to 50 µmol L−1. These MWCNTs also provided low limits of detection and quantification, 0.20 and 0.66 µmol L−1, respectively. Tea samples were analyzed by using these electrodes and recovery percentages from 99 to 109% were obtained with low relative standard deviation values, demonstrating the accuracy of the proposed sensor. Moreover, the developed SPE allowed performing the voltammetric measurements using only 100 µL of solution which is extremely attractive from an economical and environmental point of view. Therefore, this study brings exciting advances in the electroanalysis field regarding the importance of the development of disposable electrochemical sensors with improved performance and capability to perform electrochemical measurements in microvolumes.

The Structure and Phase Composition Acquired by Fe–Ti–Ni–C Alloys in Thermal Synthesis

The structure and phase composition of Fe–Ti–Ni–C alloys produced in situ by thermal synthesis at 1200°C using TiH2, Fe, graphite, and Ni powder mixtures have been studied. The synthesized alloys represent a skeleton of titanium carbide grains of different stoichiometry, with sizes varying from 0.5 to 16 μm, surrounded by metal reinforcement layers. The starting mixtures without nickel or with 5% Ni have coarse TiC grains. When Ni content of the mixture increases to 10–20%, the maximum grain size sharply decreases to 6–7 μm. The microhardness of the synthesized alloys decreases when nickel amount in the mixture increases to 15% but becomes somewhat higher at 20% Ni. The phase composition of the alloys substantially depends on the amounts of starting mixture components and includes titanium carbide, Fe3C cementite, α-iron solid solution, and intermetallic FeNi3 (for ironcontaining mixtures) and Ni3Ti and Ni4Ti (for nickel-containing mixtures). When Ni content of the starting mixture increases to 10–20%, the lattice parameter and stoichiometry of TiCx slightly decrease and carbide particles noticeably refine. The thermally synthesized alloys have been ground to produce reinforced steel composite powders, which can find extensive application in depositing wear-resistant coatings and fabricating bulky parts by compaction followed by sintering, hot pressing, or hot forging.

New and sensitive magnetic carbon paste electrode for voltammetry determination of morphine and methadone

A novel and sensitive modified magnetic carbon paste electrode (MMCPE) is introduced. Magnetic carbon paste electrode (MCPE) was fabricated by a ring magnet that was put behind an insulin syringe packed with a mixture of graphite powder, multi-walled carbon nanotube (MWCNT), and paraffin oil. The surface of the MCPE was modified by immersing the electrode in a suspension of nanomagnetic core-shell (Fe3O4@SiO2) for 20 s, while nanomagnetic core-shells were physically adsorbed on the surface of the electrode by the magnetic force. The electrochemical behavior of morphine and methadone was studied at this new modified electrode. The efficiency of MMCPE was compared with a simple CPE and two modified CPEs prepared by mixtures of (graphite + MWCNT) and (graphite + MWCNT + nanomagnetic core-shell). The results showed that the sensitivity of MMCPE was higher than the three other CPEs. As a result, direct attachment of Fe3O4@SiO2 magnetic nanoparticles to the surface of the CPE by the magnetic force showed much higher surface area and electrode sensitivity compared to when the NPs were mixed with other compounds. Our studies showed this electrode is not selectable and can be used as a general electrode for all electro-active compounds. The electro-active surface area of MMCPE was obtained by Randles–Sevcik equation. Square wave voltammetry (SWV) was applied for determination of morphine and methadone in a linear range of 5.0 × 10–9 to 1.8 × 10–6 M and 1.0 × 10–8 to 8.0 × 10–6 M, with detection limits of 1.6 nM and 3 nM, respectively. Eventually, the proposed electrode was applied to determine morphine and methadone in urine samples.

Interfacial effect between graphite and iron substrate on basal plane orientation and lubricity of graphite

The role of graphite/substrate interface in low-friction behavior of graphite was investigated. Iron and graphite powder mixtures were plastically deformed in either Ar–H2 or air atmospheres to obtain bare iron or iron oxide surface. Then, graphite particles adhered to and formed interfaces with surfaces. Friction force microscopy revealed that friction on particle surface milled in Ar–H2 atmosphere was obviously higher. X-ray absorption near-edge structure and transmission electron microscopy revealed that although the basal plane of graphite oriented along the oxidized surface, it did not occur along the bare iron surface, which explains the difference in lubricity on each surface.

STUDY OF THE OPERATING TIME OF THE PROTECTIVE COATING OF SURFACES OF ASSEMBLY AND WELDING EQUIPMENT

The subject of the study is the issues related to determining the service life of protective coatings protecting the surfaces of assembly and welding fixtures from the effects of welding spatter and mechanical wear when performing certain assembly and welding operations of welded metal structures. The development in Ukraine of various industries, especially the precision engineering industry (instrument making), is characterized by a transition to market management methods, increasing demand for competitive and liquid products. This can be achieved by the systematic and rapid introduction of technically new products, improving their quality, increasing labor productivity, and automating production. Welded metal structures are widely used in the designs of modernized and new types of products, the high-quality production of which is impossible without the use of assembly and welding equipment. The reliability and durability of these devices depends on the protection of their surfaces to the effects of welding spatter and scoring during assembly and welding operations. Analytical and experimental studies of the resistance of protective coatings to an experimental welding drop of metal showed that of the most tested coatings, the most durable is the developed protective coating containing a mixture of molybdenum disulfide powder, graphite powder, epoxy varnish and certain solvents. Purpose: determination of the service life of the developed protective coating when exposed to a number of significant factors, including the effects of real welding spatter. Tasks: to identify the main - significant technological factors affecting the service life of the protective coating; develop a planning matrix based on a full factorial experiment; to conduct experimental studies of the resistance of the coating to the effect of an experimental metal drop under the influence of significant technological factors, to obtain the equations of regression of resistance; conduct analytical and experimental studies to determine the temperature of the experimental drop of molten metal; conduct analytical studies of the temperature of a real welding spray; conduct a study of the resistance to friction; conduct analytical studies to determine the quantitative characteristics of the reliability and durability of the proposed coating composition. Results: the article presents the research data by the authors of the service life of the proposed protective coating that protects the surfaces of assembly and welding fixtures when exposed to welding spatter and coating wear when moving metal structures in the fixture. The quantitative characteristics of the reliability and durability of the coating are obtained. Conclusions: A methodology has been developed for determining the service life of protective coatings protecting the surfaces of assembly and welding fixtures from the effects of welding spatter during welding operations and coating wear when moving elements of the welding structure in the fixture during assembly.

One-step deposition of a Ni(OH)2-graphene hybrid prepared by vacuum kinetic spray for high energy density hybrid supercapacitor

Hybrid supercapacitors (HSCs) that use the nickel hydroxide-graphene hybrid (NGH) as an anode material and reduced graphene oxide (rGO) as a cathode material are a promising HSC structure. The NGH electrode is synthesized by one-step, binder-free deposition of a micro-size hydroxide powder and graphite powder mixture on nickel foam by the nanoparticle deposition system (NPDS). The NPDS is classified as a vacuum kinetic spraying approach. The electrochemical performance of the NGH-10 electrode in a 3-electrode cell demonstrates a specific capacitance of 3408 F/g at 1 A/g. The NGH-10//rGO HSC displays a specific capacitance of 180 F/g at 1 mA/cm2 in a high operating potential from 0 V to 1.6 V. The NGH-10//rGO HSC has an energy density of 64 Wh/kg @ 411 W/kg, and still 20 Wh/kg @ 8230 W/kg.

Application of TiO2 Nanoparticles Modified Carbon Paste Electrode for the Determination of Vitamin B2

In the present work, a modified carbon paste electrode was fabricated by grinding the mixture of graphite powder and paraffin oil (as a binder) with a sufficient amount of TiO2 nanoparticles. The electrochemical behavior of vitamin B2 (riboflavin) was investigated on the surface of the electrode using cyclic voltammetry and differential pulse voltammetry (DPV). The results showed that the electrochemical response of riboflavin was improved considerably at the modified electrode comparing to the unmodified electrode. Effects of TiO2 percentage, pH value, pulse time, and pulse amplitude were optimized using DPV technique. Under the optimized conditions, a linear dynamic range of 2.4 × 10–6 to 2.4 × 10–4 M with the detection limit of 1.6 × 10–6 M for vitamin B2 was obtained. The effects of some common interferences were examined, and the method was successfully employed to the detection of riboflavin in pharmaceutical formulations.