Coatings Of Different Composition Research Articles

Influence of operating parameters on the silt erosion performance of bare and coated SS304 steel

Purpose The purpose of this paper is to investigate the silt erosion performance of Bare, 75%Cr2O3 + 25%Al2O3 and 85%Cr2O3 + 15Al2O3-coated SS304 under various control parameters such as rotation speed, concentration of silt and particle size of silt used for making slurry. This can provide insight for using chromia and alumina-based coatings for hydro-turbines. Design/methodology/approach Taguchi approach was used to identify the effect of three input parameters on the bare and coated alloys. L16 orthogonal array is used for determining the signal-to-noise (S/N) ratio for each process parameter. For each level of parameters taken into consideration about the erosion wear, the arithmetic mean of the S/N ratio is calculated. On the essence of the results of S/N ratios, it is possible to determine the effect of the most dominating parameters of the erosion wear. Findings Results show that the erosion increases with an increase in silt concentration (Wt.%). It has been analyzed that the rotational speed has the most significant effect followed by the particle size and concentration on erosion wear for all uncoated and coated SS-304 samples. Maximum resistance to erosion is provided by 85%Cr2O3 + 15%Al2O3. The least erosion wear for process parameters has occurred at the optimal parametric combination of rotational speed (N) = 415 rev/min, concentration (C) = 15 Wt.% and particle size range as <53 µm for uncoated and coated stainless steel. Originality/value The study clearly shows the silt erosion performance of chromia and alumina coatings of different compositions at different input parameters. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0028/

EFFECT OF PULSED SUBSTRATE BIAS ON THE STRUCTURE AND PROPERTIES OF NITRIDE COATINGS DEPOSITED BY FILTERED CATHODIC ARC PLASMA

The results of studies of nitride coatings deposited using a cathodic vacuum arc plasma source with a rectilinear type filter are presented. The effect of parameters of high voltage substrate bias pulses on the deposition rate, composition, structure and mechanical properties of coatings based on TiN and CrN, including multi-component ones with the additions of Al, Si, Zr, Y, Re, Nb, Hf, was analyzed. With different regimes of bias potential the formation of coatings with a nanocrystalline cubic structure (of the NaCl type) and close to stoichiometric nitrogen content and high hardness of 25…36 GPa is ensured. It was found that changing the amplitude, duration and frequency of pulses allows to effectively controlling the morphology, size of crystallites, texture and stress level in coatings, which effects their mechanical properties. The use of a pulse bias potential with an amplitude of 1…2 kV, a frequency of 10…20 kHz and duty cycle of 10…15% makes it possible to form a homogeneous dense nanostructure with a [110] or [100] texture, an optimal stress level 4…5 GPa and a smooth surface in coatings of different compositions. It is shown that such a structure provides improved resistance of coatings to various types of wear. Unequivocal correlations were not found between the hardness of the coatings, the modulus of elasticity and their wear.

Chemical reaction and strength of tricalcium phosphate nano-coating application on dental implants by atomistic calculations

The success of dental titanium implants depends on the interaction of the implant with the surrounding bone, including the type of coating that promotes osseointegration. The most popular are calcium phosphate coatings, in particular tricalcium phosphate (TCP). Since cases of delamination of coatings from titanium have been observed in practice, it is important to be able to evaluate and predict the adhesion strength of coatings of different compositions to titanium.The work involves ab initio quantum chemical modeling of the interaction of TCP with titanium oxide and calculation of their binding energy. Considering that titanium instantly oxidizes in air, calculations were carried out with titanium dioxide. The Gaussian09 DFT B3LYP package with the 6-31G basis set was used. We synthesized tricalcium phosphate stepwise by assessing the binding energies between its constituents and titanium dioxide, as well as other structural characteristics including bond lengths, bond angles, dihedral angles, and charges. A method for assessing adhesion strength at the macro level using binding energy values calculated at the nano level is proposed. The values obtained are in reasonable agreement with experimental data and other numerical calculations. Using the methods of micromechanics of inhomogeneous media for the polycrystalline/amorphous structures of hydroxyapatite (HA) and β-TCP coatings, their anisotropic elastic characteristics were averaged and the degree of their closeness to the characteristics of the Ti substrate was compared.A comparison of two CFs showed that HA has an advantage over TCP both in terms of greater chemical affinity with the titanium substrate (higher adhesive bond energy) and in terms of proximity to the substrate in terms of mechanical characteristics (lower stress concentration at the bond boundary).

Atomic Layer Deposition of Antibacterial Nanocoatings: A Review.

In recent years, antibacterial coatings have become an important approach in the global fight against bacterial pathogens. Developments in materials science, chemistry, and biochemistry have led to a plethora of materials and chemical compounds that have the potential to create antibacterial coatings. However, insufficient attention has been paid to the analysis of the techniques and technologies used to apply these coatings. Among the various inorganic coating techniques, atomic layer deposition (ALD) is worthy of note. It enables the successful synthesis of high-purity inorganic nanocoatings on surfaces of complex shape and topography, while also providing precise control over their thickness and composition. ALD has various industrial applications, but its practical application in medicine is still limited. In recent years, a considerable number of papers have been published on the proposed use of thin films and coatings produced via ALD in medicine, notably those with antibacterial properties. The aim of this paper is to carefully evaluate and analyze the relevant literature on this topic. Simple oxide coatings, including TiO2, ZnO, Fe2O3, MgO, and ZrO2, were examined, as well as coatings containing metal nanoparticles such as Ag, Cu, Pt, and Au, and mixed systems such as TiO2-ZnO, TiO2-ZrO2, ZnO-Al2O3, TiO2-Ag, and ZnO-Ag. Through comparative analysis, we have been able to draw conclusions on the effectiveness of various antibacterial coatings of different compositions, including key characteristics such as thickness, morphology, and crystal structure. The use of ALD in the development of antibacterial coatings for various applications was analyzed. Furthermore, assumptions were made about the most promising areas of development. The final section provides a comparison of different coatings, as well as the advantages, disadvantages, and prospects of using ALD for the industrial production of antibacterial coatings.

Effect of silicon carbide incorporation and heat treatment on tribological properties of electroless Ni–B–W alloy coating

Concentration of reinforcing agents govern various characteristics of electroless composite coatings. In this study, silicon carbide (SiC) particles are incorporated into matrices of electroless ternary Ni–B–W alloy coatings. Addition of variable amounts of SiC into electroless bath solution used for the deposition helped in the fabrication of Ni–B–W-based electroless composite coatings of different compositions. Higher hardness value is noticed in composite coatings fabricated with the 1 g/l concentration of SiC particles in the plating bath. The resultant Ni–B–W–SiC composite coating is then subjected to heat treatment at three different temperatures (250 °C, 450 °C, and 650 °C) to study its effects on microstructural, mechanical and tribological characteristics. Alongside the composite coating, characteristics of Ni–B–W alloy coating are also observed in the same route for comparison. Matrices of as-deposited coatings show short-range order characteristics. Heat treatment at different temperatures affects magnitude of crystallization, degree of dispersion, sizes of precipitates within coatings' matrices differently. Development of various borides, such as Ni3B and Ni2B and several silicides, namely Ni3Si, Ni5Si2, and NiSi within coatings' matrices as a function of heating temperature governs the mechanical and tribological properties of coatings. Cumulative effects of composite coatings fabricated with the 1 g/l concentration of SiC particles in plating solution and heat treated at 450 °C evolved superiority in terms of mechanical and tribological properties as compared to other coated specimens in this study. Heat treatment at a higher temperature (650 °C) causes degradation in coatings’ properties due to the coarsening and coalescence of nickel boride precipitates and grain growth. Moreover, at this temperature, nickel reacts with the SiC particles and produces several nickel silicide phases, namely Ni3Si, Ni5Si2, and NiSi, negatively affecting properties of the composite coatings.

Patterns in the electrochemical synthesis of thin-film photocatalytic materials based on titanium heterooxide compounds

This paper reports a study the into processes of plasma-electrolyte formation of heterooxidic coatings on titanium alloys for the photocatalytic destruction of natural and man-made toxicants. The synthesis of coatings was carried out from aqueous solutions of diphosphates under a galvanostatic mode. For a quantitative description of photocatalytic reactions, the constants of the reaction rate kf from the linearized dependences ln(Ct/C0), where Ct is the current, C0 is the initial concentration of the reagent, were calculated. The morphology of the coating surface was investigated by atomic force microscopy, and the results were visualized by reconstruction of the relief in the form of 2D and 3D topographic maps. Morphological features of coatings made of titanium oxide (IV) and heterooxidic composites containing oxides of transition metals were analyzed. It is shown that the specific surface area remains an effective factor in regulating the photocatalytic activity of coatings. The establishment of the morphology of heterooxidic composites, as well as methods for controlling this parameter of the target product, is a constant component of the systematic study of such materials in determining their functional properties. It has been established that compared to oxide-titanium coatings whose surface layers are characterized by a toroidal mesostructure, heterooxidic compositions have a more developed surface, which has a positive effect on their functional properties. Subsequent heat treatment similarly affects the properties of the coating. The speed constants of the photocatalytic decomposition of the methyl yellow-hot azo dye were used to rank coatings of different composition according to their functional properties. Coatings from TiO2·ZnO showed the highest catalytic activity among the materials studied – kf is 5.26 10-3 min-1, which is several times higher than the corresponding value for TiO2

Design of double layer protective coatings: Finite element modeling and machine learning approximations

Thin film-composed coatings can significantly improve the mechanical and tribological properties of spacecraft friction units. In this regard, protection by ion-plasma coatings has become one of the most used options and well-established technologies. However, design of coatings that remain effective over multiple usages, is a challenge. Improving their production requires a large number of parameters to be optimized and many verification experiments to be set up. We exploited machine learning algorithm to solve the problem of double layer coatings optimization with respect to a set of mechanical properties (hardness, Young's modulus, Poisson's ratio, and yield stress). The training dataset was constructed using the adaptive sampling algorithm and numerical simulation of indentation in ANSYS for coatings of different compositions and thicknesses. The machine learning approximation provided significant accuracy (R2 > 0.96) in predicting the coating hardness based on the mechanical properties of its individual layers. The feature importance analysis of the Extra Trees algorithm was used to define the parts of the indentation curve that carry information about the properties of individual coating layers. We have also addressed the inverse problem of coatings design in terms of the required hardness. Our findings demonstrate that only tandem approach to the cross-validation task permitted correct estimation of error in the presence of multiple ambiguous solutions. The value of error was smaller than 0.15 GPa. Being comprehensive, the proposed methodology can be applied to design optimal multilayer coatings in terms of their mechanical properties for friction units in aviation and rocketry-astronautics.

MODELING THE CONTENT OF COMPONENTS OF COMPOSITE ELECTROLYTIC COVER FROM THE POLARIZATION CURRENT

The composite coatings electrodeposition with the refractory metals and zirconium with cobalt makes it possible to obtain a coating with a unique combination of physicochemical properties that are unattainable when using other application methods. One of the reasons for the limited use of the electrolytic method of coating with such composites is the difficulty of controlling the process. The properties of alloys of the iron subgroup with refractory metals and composites depend not only on the chemical composition (the content of the refractory component) but also on the deposition conditions. Varying the polarization current density allows the creation of coatings of different compositions and, accordingly, different functional properties. The basis of the work was experimental research on the physicochemical patterns of electrolytic deposition of cobalt-based composite coatings by the galvanostatic current. The purpose of the work was to develop a mathematical model of the dependence of the cobalt-containing composite coatings formation on the polarization current density. The problem of describing the electrochemical deposition of metals, alloys and composite coatings is relevant since mathematical modeling is an integral part of the development of new and improvement of existing systems. A mathematical model is proposed to control the composition of composite electrolytic coatings based on cobalt, which allows obtaining coatings of a predetermined composition when varying the density of the operating current. It has been established that the composition of coatings, in particular the content of Co, Mo, W, can be controlled by varying the electrolysis current density, using quite simple developed mathematical models. The inclusion of Zr in the composition of composite coatings is described by a more complex model, in which the parameter values depend on both the concentration of the electrolyte components and the electrolysis conditions.

Influence of W Addition on Microstructure and Resistance to Brittle Cracking of TiB2 Coatings Deposited by DCMS.

The aim of this work was to determine the influence of the tungsten addition to TiB2 coatings on their microstructure and brittle cracking resistance. Four coatings of different compositions (0, 7, 15, and 20 at.% of W) were deposited by magnetron sputtering from TiB2 and W targets. The coatings were investigated by the following methods: X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). All coatings had a homogeneous columnar structure with decreasing column width as the tungsten content increased. XRD and XPS analysis showed the presence of TiB2 and nonstoichiometric TiBx phases with an excess or deficiency of boron depending on composition. The crystalline size decreased from 27 nm to 10 nm with increasing W content. The brittle cracking resistance improved with increasing content of TiBx phase with deficiency of B and decreasing crystalline size.

Determination of Properties of Wear-Resistant Coatings of Metal Forms

Among the many different ways to improve the performance of molds for injection molding, there are those that are based on the application of thin multi-layer wear-resistant coatings by cathode-ion bombardment. However, due to the relatively small thickness of the applied coatings, measuring their parameters is a difficult task. Therefore, the article considers methods for determining the main parameters of thin multilayer coatings, such as: microhardness, separation and crack resistance coefficients, Young's modulus. The results of measurements of several coatings of different compositions are presented.

Modelling of ceramic coatings grow during Arc-PVD deposition

This paper presents the results of modeling the growth of ceramic coatings obtained by the kinetic Monte Carlo method. In the considered model, the possibility of forming misoriented grains in the direction of coating growth and in the plane of coating is realized. To verify the model, three coatings of different compositions were prepared, and their structure and composition was studied by TEM and EDS.

Effects of chitosan coating enriched with Syzygium aromaticum essential oil on quality and shelf‐life of chicken patties

Meat products are highly susceptible to spoilage. In the present study, the effect of antioxidant and antimicrobial properties of edible coating of chitosan mixed with clove essential oil was investigated for improvement in quality and shelf-life of chicken patties. The chicken patties were divided into four groups and dipped in edible coatings of different compositions. Among four groups, T1 was kept as control, T2 was dipped in 1% glacial acetic acid, T3 was dipped in 1.5% chitosan while T4 was dipped in 1.5% chitosan mixed with 0.5% clove essential oil. Treatments were analyzed for the various quality parameters for 35 days during refrigeration storage (4 ± 1°C). The results revealed that T4 had significantly (p < .05) improved quality parameters than other treatments. The study established that T4 was the most stable among all treatments with a shelf-life of 30 days while the control had a shelf-life of 10 days at refrigeration storage (4 ± 1°C). Practical applications This work provides a potential application of natural preservations of meat products dodging the use of synthetic preservatives which are detrimental for health. The shelf-life of chicken patties was extended to almost thrice by application of edible coatings. Thus, the results obtained in the present study can be replicated in meat and meat products as a natural method of preservation.

Application of finite element method (FEM) to study stress-strain state and distribution of temperatures in cutting zone in turning of various structural materials by carbide tools with coatings of various composition and architecture

The paper considers simulation of cutting process conditions and state of a metal-cutting tool using the finite element method (FEM). The study considered the distribution of normal equivalent and tangential stresses in workpiece material during turning of aluminum-deformable alloy G-AlMg5 (DIN 1725) and copper C11000. Based on the calculated stress values, the values of plastic strains of the workpiece material were determined throughout the whole process of turning with the necessary time sampling of the process. The distribution of temperatures in cutting zone during turning of steel 5135 by carbide tools with coatings of different composition and thickness was studied. The obtained results were compared with the data obtained during the corresponding cutting tests. The paper considered the influence of such coating parameters as thickness, element composition and architecture on distribution of temperatures in a workpiece, cutting tool and chips during the cutting process.

Wear nucleation in vacuum ion-plasma coatings and methods of its assessment

The paper discusses coatings of different composition and structure. The object of the study was the stage of nucleation wear of the coatings. Coatings up to 10–12 μm thick were obtained by ion-plasma deposition in a vacuum. The analytical part of the work is based on the theory of dislocations. This made it possible to create a computational model of the stage of nucleation of wear under conditions of cyclical impacts, which is problematically identified by instrumental methods. The comparison of calculated data with experimental data are given.

Easy-to-apply methodology to measure the hydrogen concentration in boron-doped crystalline silicon

Hydrogen is a highly relevant impurity in crystalline silicon associated with a variety of effects particularly important in solar cell technology such as defect and surface passivation. It has been the subject of countless studies. Much of this however relies to a certain degree on speculation due to limitations in hydrogen measurement capability, making a direct quantitative correlation of these phenomena with the hydrogen content largely impossible so far. In this contribution, we apply recent advances in the understanding of hydrogen introduction and behaviour in silicon - in particular the conversion of quenched in dimeric hydrogen to boron hydrogen pairs (BH) - and introduce an easy-to-apply methodology to determine quantitatively the hydrogen concentration in bulk boron-doped silicon. The technique involves the measurement and analysis of changes to the bulk resistivity, as recorded by contactless eddy-current measurements, due to the formation of BH pairs during annealing at temperatures between 140 and 180 °C. To demonstrate the method, we apply it to boron-doped float-zone silicon wafers with SiNx:H coatings of different compositions, introducing different total hydrogen concentrations between 5 × 1014 and 1.3 × 1015 cm−3 into the silicon bulk during a fast-firing step. Without firing, the hydrogen content is below the detection limit of 3 × 1014 cm−3 for the 1 Ω cm test sample used.

Catalytic Activity of Coatings of FeCrNiWMoCoCB Metallic Glasses on a Metal Substrate

A study is made of the catalytic activity of coatings based on FeCrNiWMoCoCB metallic glasses (MGs) on a substrate of 35 steel intended for the decomposition of a methylene blue solution. Five coatings of different composition with predominantly amorphous structure are synthesized via the precipitation of MG coating via electrosparking in an environment of granules of crystalline alloys. The roughness of coatings according to Ra is 9 to 14 µm, which considerably increases the area of interaction between MGs and the methylene blue solution. Unlike tungsten and molybdenum, the presence of nickel and cobalt in the composition of the metallic glass promotes the catalytic activity of coatings. Coatings based on the Fe33Cr8Ni8W8Mo8Co8C16B11 composition show the best catalytic properties; the energy of activation of the self-decomposition of the methylene blue solution in the presence of hydrogen peroxide falls by 800%. It is shown that the efficiency of this catalytic system can be almost tripled by etching it in HNO3 (30%) for 380 s, due to an increase in the porosity and specific surface area of the coating. The proposed approach can substantially reduce the cost of producing the catalytic elements of reactors via the one-stage deposition of coatings of MGs on metallic materials.

In vitro drug release from acetylated high amylose starch-zein films for oral colon-specific drug delivery

This study describes the preparation of free films of zein with and without acetylated high amylose maize starch (HAS) and their corresponding coated tablets as a novel approach to colonic drug delivery. We hypothesise that the embedding of a digestible starch component within the inert zein would allow the film to remain intact until the large intestine is reached. Free films of zein alone and starch/zein were prepared and characterized. SEM and AFM images of film surface showed that films were morphologically inhomogeneous, particularly at lower HAS/Zein ratios; however, nanothermal analysis data suggested that these differences in appearance within the same film are not compositional differences. Moreover, FT-IR could detect no molecular interaction between the two polymers. Paracetamol tablets were coated with HAS/Zein aqueous based coatings of different compositions to a TWG of 20%. Drug release from zein alone and 1:5 HAS/Zein coated tablets under upper gastrointestinal conditions (pH 1.2, pH 6.8 with pepsin and pancreatin included) was very similar (for example approximately 12% and 14% of the drug was released, respectively, after 6 h in a sequential in vitro test), suggesting that release in this region is limited and is not influenced by the presence of HAS in the ratio to zein under study. Studies using an in vitro colon model showed that under simulated colonic conditions, the drug release was significantly (p < 0.05) more rapid from 1:5 HAS/Zein, compared to the zein alone coating formulation. These data therefore support the potential use of zein-starch mixed films for colonic targeting purposes.

Selection of Conversion Layer Applied Beneath Thread Lubricant Coating

A polymer coating is often used instead of lubricant in order to protect the threaded part of an oil pipe fitting. There are several forms of these coatings of different composition applied by spraying to the threaded element of a pipe. Metal surface preparation before coating application has a considerable effect on polymer coating quality. Conversion coatings that formed on a pipe threaded surface and couplings as an intermediate layer between a metal surface and a polymer coatings are analyzed. The conversion coatings selected are various phosphate coatings and an alternative phosphate-free zirconium coating. Comparative study of these coatings includes an analysis of application technology, a study of conversion coatings physicochemical properties, and comparative tests for a conversion coating – thread lubricant coating system.

Projection parameters for zirconia-alumina-ceria coatings made by flame spraying from results of numerical simulation

A numerical simulation was performed with the software Jets et Poudres, the results let choose the parameters to deposit zirconia-alumina-ceria coatings of different composition on substrates of red clay, by thermal spraying with the oxyacetylene flame to obtain homogeneous coatings with good adhesion to the substrate. The effect of the projection distance (7, 10 and 12cm) between the substrate and the torch, the fusion percentage of particles and the K-Sommerfeld number was determined. This number is dimensionless and is affected by the projection distance and by the chemical composition of the particles. For a projection distance of 9cm, the fusion percentage of the particles varies between 83.8% and 100%, and the K-Sommerfeld number between 47.3 and 50 for the different compounds. This makes possible to obtain uniform coatings with good wettability, therefore, good adhesion to the substrate, while for the distance of 7cm the fusion percentage varies between 22% and 38%, due to the short time of the particles in the flame which causes low adhesion, when the projection distance is 12cm the particles do not have sufficient kinetic energy to reach the substrate and therefore the coating is not deposited.

In vitro osteoblast gene expression and differentiation atop of titanium blocks laser coated with multilayer biphasic calcium phosphate/titanium nanocomposites

In this paper, we presented a comprehensive and complete study of the biological behavior of the bone forming cells, osteoblasts, on the graded nano-biphasic calcium-phosphate/Ti coatings of different compositions by investigating bone cell proliferation, bone cell viability, markers for bone cell differentiation and key genes that encode for known proteins which are important for de novo extracellular matrix and osteoid production. We prepared the gradient nano hydroxyapatite and titanium nanoparticles (nanoTi) composite coating on Ti-6Al-4V implants. Due to the size effects of nano-Ti, this process could be used to sinter nano HA/nanoTi composite coating at low temperature. The gradient coating with different concentration of HA could be prepared by controlling the composition of the nanoparticles, and the composition of nanoHA and beta-tricalcium phosphate in the coating could be varied by controlling the laser power. The coating was characterized with XRD and SEM, and exhibited excellent biocompatibility as well as bioactivity to UMR-106 cells.