Chromium Deposition Research Articles

Chromium Electrodeposition Using Choline Chloride Based Deep Eutectic Solvent

This study investigates the possibility electrodepositing chromium in AISI 1040 carbon steel using choline chloride: urea Deep Eutectic Solvent (DES). Chrome plating has been an established manufacturing process in the industry. Due to its high corrosion and wear resistance, this process has been used in various applications such as automotive and aerospace. Traditionally, chrome plating is done using the hexavalent chromium, Cr (VI), which is considered to be toxic and hazardous, thus the need for an alternative solution that is non-toxic and safe to use arises. Deep eutectic solvents (DES) has gained interest in the chromium plating industry due to their properties such as high solubility of metals and high potential windows. Moreover, DESs are biodegradable, low cost and easier to prepare. In this work, chromium electrodeposition was done using a choline chloride: urea DES called Reline. The effect of the molar ratio and current applied on the surface morphology and hardness of the chromium deposits were investigated. Scanning electron microscopy (SEM) showed that as the current density is increased, the deposits grow outward and become powdery. This is explained by the decrease in the chromium concentration and increase in polarization.

Molten salt modelling in SPECTRA applied to MSRE

In the Netherlands, NRG has an extensive experimental irradiation program on molten salt technology. In support of this program, also system thermal hydraulic modeling capabilities are being developed in the SPECTRA code. This paper describes the (fueled) molten salt capabilities developed and presently available in the code. These include flexible input of properties and (heat) transport correlations, delayed neutron precursor drift, fission product behavior, noble gas behavior, noble metal behavior, noble metal extraction, and chromium leaching and deposition. The paper introduces the models developed and where possible their application to the Molten Salt Reactor Experiment (MSRE) data. In general, satisfactory agreements were found between experimental data and SPECTRA results, especially taking into account all the uncertainties involved in the data retrieved from MSRE which is a large integrated system test. In the next development stages, the models will be validated using separate effect tests, where clear test definition and relatively few phenomena involved will allow to quantify the accuracy of models.

Melt Pool Turbulence Effects on the Interface between Dissimilar Materials Manufactured by Directed Energy Deposition with Laser and Powder

Directed energy deposition (DED) with laser and powder allows the manufacturing of multi-metallic near net shape structures, with control over the feedstock composition and intense liquid mixing of elements. To better understand the multi-physical aspects of the melt pool and strive toward local composition prediction, a 3D finite element model of the laser deposition of chromium on stainless steel has been developed. A modified v2-f model is implemented to investigate the effect of melt pool turbulence on heat, momentum, and mass transport. The model is formulated in the moving frame of the laser, which allows reducing the domain size and the computation time. Overlapping on previous tracks is included by updating the upstream face boundary conditions with the composition and free-surface shape of the calculated molten cross section. This allows for fast computation of the steady-state solution of the layer formation. Simulation results are compared to the composition analysis of a part containing an interface between chromium and stainless steel manufactured using a controlled atmosphere laser powder-DED system. The diffusive effects induced by turbulence are analyzed with regard to a laminar simulation and are found to have a significant impact on the maximum fluid velocity and temperature. Melt pool turbulence thickens the flow vortices and homogenizes the core of the melt pool, which is consistent with the experimental results. Chemical heterogeneities can be seen at the boundary with the substrate and are reviewed in light of the simulation results.

Оptimization of the chrome plating bath operation during the restoration of vehicle parts

Introduction. In the process of chrome plating of car parts, there is a change in the composition of the chrome plating bath, which affects the stability of the ongoing processes – the performance and quality of the chrome coating. Therefore, it is necessary to constantly monitor the chrome plating bath for the presence of foreign elements that can be formed during the operation of the bath during the reaction of the solution with the anode or cathode.Materials and methods. During the research, the necessary equipment was used, which made it possible to determine with sufficient accuracy the content of trivalent chromium and its effect on the electrolysis process – the performance and quality of chrome coatings. A well-known technique was used to determine the quality and performance.Results. When conducting studies of the obtained cold self-regulating chromium plating electrolyte, it was found that trivalent chromium has a significant effect on the stability of the chromium plating bath. The content of which can vary within 2...25 g/l during operation. As a result, it was found that the optimal amount of trivalent chromium is its content in the chromium plating bath from 2 to 15 g/l. With a lower or higher content, the electrolysis performance and the quality of the chrome coating decrease. It was also found that in order to maintain the optimal amount of trivalent chromium and increase the time for stable operation of the chromium bath, it is necessary to observe the ratio of the area of the anode and cathode (the coated surface of the part), the value of which is within 3...4.Discussion and conclusion. As a result of the conducted research, it will make it possible, under certain conditions, to carry out the process of chromium deposition from a cold self-regulating electrolyte, which will allow for stable chromium deposition at high productivity and the necessary quality of the coatings obtained. The main condition is to control and maintain the amount of trivalent chromium in the chromium plating electrolyte in the bath.

Electrodeposited Co-P alloy and composite coatings: A review of progress towards replacement of conventional hard chromium deposits

Hard chromium coatings have attracted much attention due to their strong tribological and corrosion performance. There is a global need to replace such coatings in industrial applications owing to technical problems, environmental concerns and legislation. Co-P electrodeposits are a promising alternative to hard chromium in a variety of engineering applications due to their appreciable microhardness and high corrosion resistance . Attractive magnetic, tribomechanical and electrical properties are evident together with excellent thermal stability. Environmentally acceptable process conditions may be used which allow controlled deposition on diverse workpieces across a wide scale. This review provides an overview of the influence of operational parameters, including type of current control, electrolyte composition, pH, current density and electrolyte agitation on the physicochemical and mechanical characteristics of the deposits. The incorporation of ceramic particles into Co-P electrodeposits to produce tailored composite coatings is also considered. An insight is given into the development of next generation alloy and composite deposits to replace hard chromium deposits from acidic Cr(VI) baths. Diverse applications for Co-P electrodeposits are considered and topics deserving further R & D are highlighted. • A concise overview of Co-P alloy electrodeposits is provided. • The most common types of bath used for Co-P electrodeposition are considered. • The influence of operating conditions on properties of deposits is addressed. • Effects of included particles on deposit characteristics are comprehensively discussed. • Potential applications of Co-P films are highlighted.

Investigating Effects of Operational Parameters on the Rate of Electrochemical Cleaning of Chromium Deposits on Strontium-Doped Lanthanum Manganite Cathodes in Solid Oxide Fuel Cells

Chromium poisoning of the cathode remains a significant obstacle to the long-term performance of solid oxide fuel cells. Previously, a quick, easy method was introduced that requires no material modifications, major thermal cycling, nor exposes the cell to any species it does not already encounter during operation. The method, electrochemical cleaning, reverses the electrochemical deposition reaction of chromium-containing species by applying a mild anodic bias. Chromium vapor species are formed, freeing active sites in the cathode. The method has been shown to completely recover cell performance via this current-voltage technique.The present work investigates the mechanism of electrochemical cleaning by assessing the effect of various operating parameters on the rate of chromium removal. Using a design of experiments method, eight cells were poisoned and then cleaned using differing combinations of the following cleaning parameters: cell temperature, air humidity, anodic current density, and fuel humidity. Regression analysis of two comparative metrics, cell performance via current voltage curves and post-test chromium content determined via Energy Dispersive Spectroscopy, demonstrated that cell temperature has the highest effect on the rate of chromium removal, followed by air humidity. A refined parameter space for future study is proposed for further optimization of the parameters. Previously, the electrochemical cleaning method was shown to be effective in the removal of Cr2O3 deposited species, but not Cr-Mn spinel deposits. The effects of operating parameters on the removal of the two different types of Cr deposits is discussed. An additional process for the removal of Cr-Mn spinel is demonstrated, which again makes use of the cell operating parameters. Together, the two methods present a facile, periodic process to greatly extend solid oxide fuel cell lifetime.

Molten salt modelling capabilities in SPECTRA and application to MSRE and Mk1-PB-FHR

In support of extensive experimental irradiation program on molten salt technology at NRG in the Netherlands, system thermal hydraulic modeling capabilities are being developed in the SPECTRA code. This paper describes the (fueled) molten salt capabilities developed and presently available in the code. These include obviously flexible input of properties and (heat) transport correlations, delayed neutron precursor drift, fission product behavior, noble gas behavior, noble metal behavior, noble metal extraction, and chromium leaching and deposition. The paper will introduce the models developed and where possible their application to the Molten Salt Reactor Experiment (MSRE) data and simulation of the Mk1-PB-FHR.

Investigating Effects of Operational Parameters on the Rate of Electrochemical Cleaning of Chromium Deposits on Strontium-Doped Lanthanum Manganite Cathodes in Solid Oxide Fuel Cells

Chromium poisoning of the cathode remains a significant obstacle to the stable long-term performance of solid oxide fuel cells. This study reports, a quick, in-situ mitigation method, called electrochemical cleaning. By applying a mild anodic bias, the electrochemical deposition reactions of chromium-containing species are reversed. Chromium vapor species are formed, freeing active electrochemical sites in the air electrode. An LSM/YSZ-based cell was exposed to Cr vapors at 800ºC and then subjected to electrochemical cleaning. Cell performance recovery was evidenced by current-voltage and EIS measurements. Chromium removal was verified using SEM and EDS analyses. The cyclability of the electrochemical cleaning was tested by repeated poisoning and cleaning of another cell. Investigation into the effect of cell operating parameters (current density and cell temperature) on the rate of cleaning is discussed.

Magnetron Sputtering vs. Electrodeposition for Hard Chrome Coatings: A Comparison of Environmental and Economic Performances.

The coating of materials with specific films is widely used to improve material properties and many technologies exist to perform it. In the last few years, the replacement of wet electrodeposition processes has been continuously encouraged in the EU due to the problematic waste management linked to those processes. In this paper, magnetron sputtering is studied as an alternative to conventional electrodeposition by comparing the technologies’ environmental impacts and costs. From the study, it appears that while magnetron sputtering greatly reduces hexavalent chromium emissions over the production, it has an increased electricity consumption mostly due to its lower production capacity, thus leading to more greenhouse gas emissions. Furthermore, a short discussion on the quantification of the impact of hexavalent chromium emissions is conducted. Regarding costs, the electrodeposition process has a lower cost of investment and of consumables, but requires more work time for the different steps of the process, making the total price per functional unit roughly equal. However, the cost per functional unit strongly depends on assumptions on the required work time, for which a sensitivity study is performed. Finally, the impacts of these two competing coating processes are discussed to complete the technological comparison for the case of hard chromium deposition.

Transportation of Chromium (VI) to Bombyx mori L. from mulberry Plant (Morus alba L.) grown at soil irrigated with Chromium (VI) containing effluents

The research was conducted to determine Chromium (VI) toxicity in population Bombyx mori. The synthetic wastewater used to irrigate soil to evaluate the impact of pH (4 to 8) at 100 mg/L and initial Chromium (VI) concentrations (25 mg/L to 300 mg/L) at 5 pH in its bioaccumulation in B. mori foodchain. By using atomic absorption spectrophotometer (AAS) analysis the amount of Chromium (VI) determined in soil, mulberry plants, B. mori larvae, silk glands and silkworm feces. The results showed that local cobalt pollution can be indicated by using B. mori as a template as its body length, body weight and the mortality rate were found to be strongly related to Chromium (VI) concentration. Higher the Chromium (VI) amount in mulberry leaves causes more toxicity to B. mori population. At 300 mg/L Cr (VI) concentration and pH 4 there was maximum deposition of Chromium (VI) in soil, mulberry plants, B. mori larvae, faeces and silk glands from the synthetic effluent. The maximum deposition was 123.5±0.03 mg/kg, 89.76±.031 mg/kg, 23.31±0.019 mg/kg, 41.32±0.069 mg/kg and 35.67±0.04 mg/kg observed respectively.

Characterization of the Chromium (III)-Glycine Complexes in Acidic Medium by UV-Visible Spectroscopy and Capillary Electrophoresis

Since 2017 REACH restrictions on hexavalent chromium, aeronautic industries have been involved in the substitution processes for chromium plating. So far, the use of trivalent chromium-based precursors seems to be the best solution in terms of process adaptation. The development of such process is nested on a better understanding on solution chemistry of the plating bath. More specifically, it is needed to characterize the complexation mechanisms occurring with the chromium (III), since they are responsible for a higher electrodeposition efficiency. Chromium (III) complexation occurs under specific conditions such as acidic solution, where chromium hydrolysis takes place, leading to a stable aqua chromium complex, which is suspected to be detrimental to an even deposit. To tackle this issue, a complexing agent is added to destabilize hexaaquachromium complex. It is reported that ligands as glycine allow the formation of chromium-ligand complexes under specific pH and chromium-ligand ratio. In order to identify, and to understand the formation of the various complexes, two characterization methods have been intended: UV-visible spectroscopy, which allows the identification of chromium complexes through the d-d electronic transition in the UV-Visible range, and capillary electrophoresis, as separation method, coupled to UV-visible detection in order to identify and quantify each species. UV-visible spectroscopy and capillary electrophoresis analyses revealed that no glycine-chromium complex was observed for pH lower than 2, which are the regular condition for electrodeposition. Only a lower Cr:Gly ratio and/or a pH higher than 2 allowed observing glycine-complexes in the solution. As these conditions could be met during electrodeposition nearby the substrate/electrolyte interface, it is highly likely that the chromium depletion together with the pH increase occurring would favor the formation of glycine-complexes at the interface, which were reported to be required to achieve homogeneous chromium deposits.

THE EFFECT OF CHROMIUM STRESS ON MICRO-ANATOMICAL PROFILE OF CHILI (Capsicum annuum L.)

Chromium contamination can affect morphological, physiological, and anatomical changes, especially in chili vegetative organs. This research aims to understand micro-anatomical structure of the vegetative organs of chili subjected to chromium stress. The aim of the research is to know whether there is a micro-anatomical character difference between contaminated and uncontaminated chromium. The experimental methods using a completely randomized design (CRD). The independent variable is five levels of chromium concentration, i.e., 0; 50; 100; 200; and 300 ppm. The method of preparing anatomical preparations of the stem using a non-embedding and embedding method. The parameters observed in root and stem are organ diameter, xylem, thick of epidermis, and cortex. In contrast, leaf organ parameter includes thick cuticle, epidermis, mesophyll, stomata size (length and width), and stomatal number. The research results showed that organ anatomical structure, i.e., root, stem, and leaf in chromium stress condition did not change. Chromium deposition causes a decrease in root diameter, xylem, thick cortex roots, stem diameter, xylem, the thickness of the epidermis and cortex, leaf epidermal thickness, mesophyll, size of stomata width and number. In contrast, the chromium stress causes an increase in the thickness of the root epidermis (43,18%), cuticle thickness (36,36%), and leaf stomata length (33,33%) of chili as chromium concentrations increase. The anatomical structure of chili leaves changes after being contaminated chromium stress.

Single pulse development of chromium-deposited imprint micro/nano patterns of photo-cured crosslinked resin using a femtosecond pulsed laser

Exposure to a single pulse generated from a femtosecond pulsed laser for a duration of 100 fs at a wavelength of 800 nm and a laser fluence of 0.31 J cm−2 resulted in chromium (Cr) deposition on photocured insoluble imprint resin patterns to be ablated selectively; however, Cr deposition on synthetic quartz surfaces was retained. Single-pulse development of Cr-deposited imprint micro/nano patterns occurred at the same laser fluence, independent of the presence of a laser absorbing dye. Laser ablation of the cured resin near the Cr deposition was confirmed by atomic force microscopy. Depth profile analyses confirmed that Cr species were partially embedded in the cured resin underneath the layer of Cr. These results suggest that the mechanism of laser ablation was due to the rapid thermal expansion of resin near the embedded Cr species and deposited Cr layer rather than the multi-photon absorption of the cured resin.

Formation of residual stresses during the restoration of parts by chrome electroplating

As the title implies the influence of the electrolysis on the nature and magnitude of residual stresses in the steel base and the chrome coating during restoration of parts has been considered. It has been shown that with an increase in compressive stresses on the surface, a decrease in tensile stresses in the chromium deposit and transition of tensile stresses to compressive ones near the boundary of the base are observed. A correlation between the parameters of the crystal lattice of electroplated chromium and the steel base has been established. The values of the tensile residual stresses in the chromium deposit decrease with increasing the compressive residual stresses in the base.

Fabrication Protocol for Thermoplastic Microfluidic Devices: Nanoliter Volume Bioreactors for Cell Culturing.

Microfluidic devices consist of microchannels etched or embossed into substrates made of polymer, glass or silicon. Intricate connections of the microchannels to reactors with some smart mechanical structures such as traps or curvatures fulfil the desired functionalities such as mixing, separation, flow control or setting the environment for biochemical reactions. Here, we describe the fabrication methods of a thermoplastic microbioreactor step by step. First, material selection is made, then, production methods are determined with the equipment that can be easily procured in a laboratory. COP with its outstanding characteristics among many polymers was chosen. Two types of microbioreactors, with and without electrodes, are designed with AutoCAD and L-edit softwares. Photolithography and electrochemical wet etching are used for master mold preparation. Thermal evaporator is employed for pure chromium and gold deposition on COP substrate and etchants are used to form the interdigitated electrodes. Once the master mold produced, hot embossing is used to obtain the designed shape on drilled and planarized COP. Cover COP, with or without electrodes, is bonded to the hot embossed COP via thermo-compression and thermoplastic microfluidic device is realized. Tubings are connected to the device and a bridge between the macro and micro world is established. Yeast or mammalian cells labeled or tagged with GFP/RFP on specific gene products are loaded into the microfluidic device, and real time data on cell dimensions and fluorescence intensity are collected using inverted fluorescence microscope, and finally image processing is used to analyze the acquired data.

Свойства хромовых покрытий, нанесенных различными методами на циркониевый сплав Э110

The issue presents the results of studies of methods for increasing the corrosion resistance of fuel claddings made from zirconium alloy E110, performed at the SRC RF TRINITI, using coatings (Al, Al2O3, Cr) by pulsed laser deposition, as well as magnetron sputtering and galvanic deposition of chromium. Also presented some results of studies of adhesion, microstructure and corrosion resistance of chromium coatings deposited by various methods. It was revealed that the corrosion resistance of the cladding of fuel rods with chrome coatings at temperatures of 1100 – 1200 °С practically does not depend on the method of their application. However, the coating method has a significant effect on their adhesion, with coatings obtained by atomic deposition methods and characterized by a continuous uniform structure have the greatest adhesion. The depth of oxidation of the outer surface of the cladding of a fuel rod when applying a chromium coating decreases by an average of 30 times for sponge-based alloy E110.

Characterization of chromium (III)-glycine complexes in an acidic medium by UV-visible spectrophotometry and capillary electrophoresis

Since the 2017 REACH restrictions on hexavalent chromium, the aeronautics industries have been seeking substitute processes for chromium plating. So far, use of trivalent chromium-based precursors seems to be the best solution in terms of process adaptation. The development of such processes requires a better understanding of plating bath solution chemistry. More specifically, there is a need to characterize the complexation mechanisms occurring with the chromium (III), since they are responsible for higher electrodeposition efficiency. Chromium (III) complexation occurs under specific conditions, such as in an acidic solution, where chromium hydrolysis takes place, leading to a stable aqua chromium complex, which is suspected to be detrimental to an even deposit. To tackle this issue, a complexing agent is added to destabilize hexaaquachromium complex. It is reported that ligands such as glycine allow the formation of chromium-ligand complexes under specific pH and chromium-ligand ratios. In order to identify and understand the formation of the various complexes, two characterization methods have been tested: UV–visible spectrophotometry, which allows identification of chromium complexes through d-d electronic transition in the UV–Visible range, and capillary electrophoresis as a separation method, coupled with UV–visible detection in order to identify and quantify each species. UV–visible spectrophotometry and capillary electrophoresis analyses revealed that no chromium-glycine complex was observed for pH lower than 2, which is the regular condition for electrodeposition. Only a higher Gly:Cr ratio and/or pH>2.4 (i.e pKa1 of glycine) made it possible to observe glycine complexes in solution. As these conditions could be met during electrodeposition near the substrate/electrolyte interface, it is highly likely that chromium depletion, together with the pH increase that occurs, could favor the formation of glycine complexes at the interface, which have been reported as being required to achieve homogeneous chromium deposits.

Ecological risk assessment of toxic metal contamination in a significant mining basin in Turkey

Emet River Basin is a worldwide significant mining area and contains the most important boron and chromium deposits of Turkey. In this study, water and sediment quality of Emet River Basin was evaluated using some toxic element risk assessment indices. Samples were collected seasonally from 8 locations and nickel (Ni), chromium (Cr), arsenic (As), zinc (Zn), lead (Pb), copper (Cu) and cadmium (Cd) accumulations in water and sediment were analysed using an ICP-OES. Water Quality Index (WQI), Heavy Metal Pollution Index (HPI), Heavy Metal Evaluation Index (HEI) and Degree of Contamination Index (Cdeg) were applied to the data for assessing the water quality and Biological Risk Index (BRI), Potential Ecological Risk Index (PERI), Geo-Accumulation Index (Igeo), Contamination Factor (CF) and Pollution Load Index (PLI) were applied to the data for assessing the sediment quality. According to the results of WQI, HPI, HEI and Cdeg, As and Cr were recorded as the most dangerous toxicants; according to the results of BRI, Igeo, CF and PLI, Cd, As and Pb were recorded as the most dangerous toxicants; and according to the results of PERI, Ni and Cr were recorded as the most dangerous toxicants among the investigated elements. The seasonal average values of applied ecological indices for the water of the basin ranged 71.41–888.29 for WQI, 85.97–915.76 for HPI, 4.04–49.80 for HEI and − 2.95–42.80 for Cdeg. The seasonal average values of applied ecological indices for the sediment of the basin ranged 33.72–130.56 for PERI, 0.14–0.93 for BRI, − 3.92–5.99 for Igeo and 0.45–1.20 for PLI. In addition to the intensive agricultural applications around the region, the geological structure of the watershed was considered as the main cause of the high heavy metal accumulations in basin waters and sediments.

Investigation of The Reaction Kinetics of Chromium(III) Ions with Carboxylic Acids In Aqueous Solutions and The Associated Effects on Chromium Deposition

Electroplated chromium is an important industrial coating. Both in the decorative and functional field, research is being carried out to develop trivalent chromium electrolytes. In this work, the interaction between CrIII ions and carboxylic acids (malonic acid, malic acid, oxalic acid and glycolic acid) is investigated. The use of carboxylic acids to improve the current efficiency in trivalent chromium plating baths has been known for a long time. But the thermodynamics and kinetics of the associated complexing reactions are not well understood. It is shown that the complexes form at different rates depending on the acid and its concentration and have a varying influence on chromium deposition. For the development of a technical bath, care must be taken to ensure that the molar ratios between chromium and carboxylic acids can be controlled. This is possible with the HPLC method presented here.

Honey Bees and Their Products as Indicators of Environmental Element Deposition.

The aim of this study was to evaluate element (sodium, magnesium, potassium, calcium, chromium, manganese, iron, cobalt, nickel, copper, zinc, arsenic, cadmium, and lead) deposition in honey bees (Apis mellifera L.) (worker bees, drone bees, and bee broods) and their products (wax and multifloral honey) in the central and north parts of Serbia using inductively coupled plasma mass spectrometry (ICP-MS). The study was carried out during the spring and summer seasons when the honeybees were active (2019). Fifty-four colonies of honey bees from different apiaries (located in Rudnik, Lazarevac, and Ležimir) were used in this study. Significant differences in element concentrations were found among locations (P < 0.05). The highest deposition of elements (sodium, calcium, manganese, iron, cobalt, nickel, zinc, arsenic, and cadmium) was found in worker bees. The most commonly detected elements in wax were chromium and lead. Mg had a significant (P < 0.01) correlation with K, Fe, Cu, and As. This study shows that honey bees (worker bees, drone bees, and bee broods) could be more useful as bioindicators of environmental element deposition (toxic and non-toxic) than multifloral honey. Also, this study shows that Serbian multifloral honey meets safety criteria concerning the concentrations of toxic elements.