Bath Composition Research Articles

Effects of Bath Composition and P Contents on the Mechanical Properties of Ni-P Electroplating

Ni-P alloys are fabricated on the pre-cleaned copper substrate using electroplating method in sulfate bath. The concentration of phosphorous acid and current density were varied to optimize the P contents as well as the physical properties of the alloy. The properties of Ni-P alloy were analyzed using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The surface hardness of the Ni-P alloy was increased up to 550 Hv as the phosphorous acid (H3PO3) increased upto 0.015 M, however the higher phosphorous contents in the coating developed the cracked on the surface. The surface hardness was increased due the grain refinement.

Studies on the characterization and morphological features of the coating on interstitial free steel dipped in molten Al-Si-Mg alloy at 800 °C

Interstitial-free (IF) steel specimens were coated by hot-dip aluminizing process bearing bath composition as Al-6.9% Si-1.4% Mg and bath temperature at 800°C. Dipping time varied for 0.5, 1, 3 and 6min. The objective of the present study is to conduct a systematic investigation to identify and analyse the formation of various phases and compounds in the coating. Studies on aluminizing of steel had indicated the presence of an intermetallic layer adjacent to steel substrate. In this study, the morphological features obtained after hot dipping at 800°C were investigated. For the application of aluminized steel sheets in industry for manufacture of tubes and pipes, the adherence of the aluminized coating must be ensured. This property of the coating is influenced by the morphological features of the coating. Aluminizing being thought of a possible substitution of galvanizing owing to its promise to evolve lesser volume fraction of intermetallic phases and consequently known to generate a ductile coating. The entire coating consists of an outer Al-Si topcoat and a thin intermetallic layer which composed of an outer θ-FeAl3 and inner η-Fe2Al5 layers. The thickness of intermetallic layers was found to increase with the increase of dipping time in a near parabolic manner.The phases formed on the IF steel substrates were characterized by scanning electron microscopy with EDS, X-ray diffraction, EPMA and EBSD techniques.Interesting findings from XRD include the presence of Al3FeSi2 (τ4) and Al2FeSi (τ3) phases, which normally appear after annealing of aluminised sheet. A distinct elemental Si peak was found in XRD study. Presence of Mg in the form of Mg2Si was also found in XRD and supported by EPMA investigation. Presence of several ternary Al-Fe-Si (τ3, τ4, τ5) and binary FeAl3 and Fe2Al5intermetallic phases were identified by composition profile analysis from SEM based EDS and GDOES and further confirmed by EBSD. Presence of Si humps in the top and intermetallic layer attributed by the presence of Si-bearing phases or elemental pro-eutectic Si in Al-Si alloy were also indicated in SEM-EDS and GDOES study. Variation of surface topographical features of the HDA steel substrates with increasing dipping durations were examined and reported for the first time by using AFM. Formability tests were conducted by bending the samples 180° over a mandrel. None of the specimens showed any tendency of flaking exhibiting excellent bonding of the coating with IF steel substrate.

Compositional and Bath Temperature Effects on Heat Transfer During Quenching in Molten NaNO3–KNO3 Salt Mixtures

The present study involved the assessment of cooling severity of molten NaNO3–KNO3 mixtures which are widely used as quench media for austempering and martempering operations. An Inconel probe instrumented with thermocouples was quenched in molten NaNO3–KNO3 binary mixtures of varying concentration maintained at different quench bath temperatures. The temperature data acquired at various locations in the Inconel probe during quenching was used to calculate the spatially dependent transient heat flux at the metal–quenchant interface. Two critical points corresponding to peak heat extraction rates during the nucleate boiling stage and transition from boiling to convection stage were identified for each quench medium. The variation of average heat flux and average surface temperature corresponding to these critical points was mapped with variation in bath temperature and composition of the quench medium. AISI 4140 steel probes were quenched in these quench media maintained at 300 and 350 °C. The average hardness values measured in steel probes agreed with the cooling performance of these quench media determined using Inconel probe. The degree of uniformity in heat transfer as indicated by the spatial variation of normalized heat energy decreased with the increase in the concentration of KNO3 in the quench medium. A mechanism of boiling heat transfer during quenching based on thermochemical decomposition of the salt was proposed.

The electrodeposition of composite coatings: Diversity, applications and challenges

Abstract A wide range of coatings can be produced by incorporating particles into an electrodeposit. The matrix may be a metal, conductive polymer or conductive ceramic, whereas the particle can be metallic, polymeric, ceramic or combinations of spheroidal, irregular or layered inclusions. Nanostructured, gradient, multilayer and sandwich layer deposit further widen possibilities. Electrochemical approaches to the deposition of composite coatings offer the benefits of good control over deposition rate (hence thickness), coating composition and deposit properties. Both faradaic electrodeposition and electrophoresis are usually involved. This review focuses on nanosized inclusions in a metal matrix over the last two decades. Interactions between bath composition, particle dispersion, operational variables and resultant deposit properties are poorly documented in the literature. Our understanding of the mechanism of composite deposition remains patchy, despite progress and computer models are scarce. Electrode geometry, electrolyte hydrodynamics and current distribution remain poorly treated. Markets in electronics, surface engineering, aerospace, corrosion protection and electrochemical energy conversion have been stimulated by newer uses for self-cleaning, superhydrophobic and biocompatible surfaces. Challenges to be met by further research and development are prioritised.

Pulse plated Sn-Cu solder coatings from stannate bath

PurposeThe purpose of this paper is to investigate the influence of pulse plating current density on the morphology and solderability of Pb-free Sn-Cu solder coatings prepared from alkaline stannate baths.Design/methodology/approachSn-Cu solder coatings were produced from a plating solution containing sodium stannate, copper stannate, sodium hydroxide and sorbitol additive on copper substrates. The pulse plating experiments were conducted in galvanostatic mode. The plating current density was varied from 5 to 25 mA/cm2, and the morphology of the coatings was studied. The solderability of the coatings was assessed by spread ratio measurement after reflowing the solder coatings at 250°C.FindingsThe composition control of eutectic solders is always a challenge in plating. The findings show that Sn-Cu coatings prepared by pulse plating are composed of tetragonal ß-Sn structure and Cu6Sn5 compounds irrespective of bath composition and conditions. The final coatings were very dense and smooth with nodular morphology. It was shown that a eutectic composition can be achieved if we apply a current density of ∼15-20 mA/cm2. The solderability studies suggest that solder coatings plated at and beyond 15 mA/cm2 are more suitable for solder finish applications.Originality/valueThe work presents key issues in pulse electroplating of Sn-Cu solder coatings from an alkaline bath. Possible strategies to control the eutectic Sn-Cu composition by plating process are recommended.

A Model for the Faradaic Efficiency of Base Metal Electrodeposition from Mildly Acidic Baths to Rotating Disk Electrodes

Base metal electrodeposition is inevitably accompanied by parasitic hydrogen evolution. This results in a less-than-unity Faradaic efficiency (FEm) of metal deposition that is known to depend on many factors like the applied current density, the composition (primarily, the metal ion concentration and the pH) of the depositing bath, and the rate of convection. Analysing how FEm values depend on the current density j under well-defined transport conditions (e.g., by the use of rotating disk electrodes) became an integral part of industrial approaches to the screening of bath compositions applied for base metal electroplating. Yet FEm(j) curves are still not very well understood, and most studies content themselves with their mere qualitative analysis, reaching no conclusions as to the mechanisms of the underlying reactions. We attempt to fill this gap by creating a simple model for FEm(j) curves based on first principles. The presented model can very well be fitted to experimental data obtained for the electrodeposition of nickel and of cobalt, and it yields a consistent set of kinetic and transport parameters over a broad range of pH, rotation rates and current densities. The presented model thus paves the way towards a knowledge-driven benchmarking strategy of base metal electroplating baths.

Electroless Plating Lead and Lead-Tin on Copper Using an Eco-Friendly Plating Bath

Copper serpentines used in gas heaters are currently coated with lead-tin alloy using hot-dip technology where copper is immersed in molten lead (98%)-Tin at about 400°C. The major drawback of this technique is the pollution resulted from lead vapors which cause much harm to the labors in the unit. The present work investigates an eco-friendly plating technique to replace the currently used technology. Electroless plating of copper samples with lead or Lead (98%)-Tin alloy is carried out from a plating bath contained lead salt, tin salt, reducing agent and stabilizing agent. The parameters affecting the coating quality such as the plating time, temperature and bath composition were optimized. The chemical analysis and coating morphology of the formed coatings are examined by XRD, SEM and EDS to reach the best bath composition as well as the best conditions to coat copper with lead or lead-tin electrolessly. The electrochemical properties of copper and copper coated samples are also examined using electrochemical impedance spectroscopy.

Влияние состава осадительной ванны на структуру и свойства волокна, получаемого мокрым методом из растворов поли[акрилонитрил-со-метилакрилат-со-2-акриламид-2-метилпропансульфокислоты] в апротонных и гидротропном растворителях

Влияние состава осадительной ванны на структуру и свойства волокна, получаемого мокрым методом из растворов поли[акрилонитрил-со-метилакрилат-со-2-акриламид-2-метилпропансульфокислоты] в апротонных и гидротропном растворителях

Development of Nanostructured Ni–Fe Alloy Coatings; Characterisation and Corrosion Analysis

The present investigation deals with the electrofabrication of nanostructured Ni-Fe alloy coatings on a mild steel using sulfate bath. The electrolytic bath composition and the current density of the coatings were optimized. Composition analysis by energy dispersive X-ray spectroscopy revealed that the Ni–Fe alloy coatings are of anomalous type. Potentiodynamic polarization corrosion test and electrochemical impedance spectroscopy methods in 3.5% NaCl solution direct towards the lowest corrosion rate at 4 A dm–2. Hardness and roughness of the coatings were evaluated using Vickers hardness test and atomic force microscopy, respectively. The surface morphological analysis of the coatings was characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy. The phase structure, the texture coefficient, and the crystallite grain size of the coatings were calculated and studied using X-ray diffraction.

A Method for Electroless Nickel Plating on Aluminum Alloy Surface

According to the following plating processes: deoiling → washing → pickling → washing → drying → weighing → electroless plating → washing → drying → weighing. It can obtain Ni-P deposit on aluminum alloy. It studied the influence of bath composition and process parameters on the composition and deposition rate of the alloy coating. Under temperature of 85~90°C, nickel sulfate hexahydrate 15~35g/L, sodium hypophosphite 10~30g/L, sodium citrate 5~10g/L, tartaric acid 1~2g/L, pH 3~5, reaction time 30~60min, load factor 1.0~2.0dm²/L. The microstructure, surface morphology, composition and valence of the elements in the alloy coating were studied by metallographic microscope, SEM, EDS and other modern analytical methods. The size of spherical grain was below 1um and compact distribution. The chemical coatings were mainly composed two elements, which were phosphorous and nickel. The mass percentage of phosphorous was about 15%, and the other one was about 80~85%. The corrosion resistance of the alloy coating was studied by CASS [1] test method, through 80h CASS test detection, the protection class of chemical coating can be reached 5. The relevant evaluation criteria can be referred to GB/T 6461-2002 [2]. The results show that the Ni-P binary amorphous alloy can be successfully prepared by this process.

Flame-retardant treatment of wool and wool-rich blends: A study of bath composition

Wool and wool-polyamide blended yarns (88.6% wool–11.4% polyamide 6,6 and 78.5% wool–21.5% polyamide 6,6) were knitted and the produced fabrics were treated by exhaustion method with zirconium complexes. Six different baths containing potassium hexafluorozirconate and zirconium acetate were studied. The flammability hazard was evaluated considering parameters such as the spread of flame, the heat release and the smoke release rate. Regardless of the blend composition, the untreated fabrics could not pass the vertical flammability test. 100% wool fabric could pass the vertical flammability test when treated with only 1% potassium hexafluorozirconate and 10% zirconium acetate solution. Higher compositions of metal complexes were required for the blended fabrics to pass the vertical flammability test. In the cone calorimeter test, 100% wool treated with 5% potassium hexafluorozirconate and 10% zirconium acetate solution gave the lowest peak heat release and smoke release rate values as 146.4 kW/m2 and 1.2 s−1, respectively.

Nano SiC Reinforced Copper Nanocomposite by a Simple Electrodeposition Method

The Cu and Cu-SiCnanocomposite coatings were prepared by a simple electrodeposition technique from acidic copper sulphate electrolyte using SiC nanoparticles with an average particles size of 50 nm under optimized bath composition and preparation conditions for possible electrical contact material applications such as electrical switch and wiring boards where higher electrical conductivity and thermal conductivity is required. The scope of the present study is to enhance the strength, mechanical, corrosion and wear resistance properties of Cu-SiCnanocomposite compared to pure Cu coatings. The as prepared Cu and Cu-SiCnanocomposites were characterized for structural, mechanical and corrosion resistance properties by EDX, XRD, FESEM, Vickers microhardness tester and AC-impedance and Tafel polarization techniques. The elemental composition (wt% of Cu and SiC nanoparticles) of Cu-SiCnanocomposites was analyzed by EDX coupled with FESEM analysis confirms the presence of nanoSiC in the copper matrix and they were 89wt% of Cu and 11 wt% of SiC nanoparticles respectively. The surface morphology of Cu and Cu-SiCnanocomposites was studied by FESEM analysis shows that SiC nanoparticles were uniformly dispersed in the surface of the copper matrix compared to pure copper. The crystallite structure and grain size of the Cu and Cu-SiCnanocomposite electrodeposits was measured by XRD analysis. From the XRD results, the grain size calculated using Debye-Scherrer’s formula was ~35 nm for pure Cu and ~33 nm Cu-SiCnanocomposite. The crystallite structure of Cu and Cu-SiCnanocomposites was fcc (face centered cubic) and the preferred orientation of the plane was (220). The microhardness of Cu-SiCnanocomposite coating increased with increasing SiC nanoparticles concentration in the bath compared to pure Cu coating. The corrosion resistance measurements were performed for the pure Cu and Cu-SiCnanocomposite coatings by electrochemical impedance spectroscopy (EIS) and Tafel polarization techniques. It shows that, Cu-SiCnanocomposites has high corrosion resistance than pure Cu in 3.5wt% NaCl solution.

Study of the Morphology and Properties of Biocompatible Ca-P Coatings on Mg Alloy.

Magnesium alloys are considered as potential biomaterials for use in orthopedic implantology. The main barrier to the use of Mg alloys in medicine is their overly fast and irregular degradation in body fluids. The use of protective calcium phosphate coatings to increase the corrosion resistance of Mg alloy (AM50 alloy: 4 wt.% Al, 0.3 wt.% Mn, 0.2 wt.% Zn, rest Mg) was examined in this study. The scientific goal of the study was the assessment of the influence of calcium phosphate layer morphology on the corrosion process in Ringer’s solution. Modification of the coating morphology was obtained by changing the chemical composition of the phosphatizing bath using NaOH (NaAM50 sample) or ZnSO4 (ZnAM50 sample). In practice, a more dense and uniform coating could be obtained by the immersion of AM50 alloy in a solution containing ZnSO4 (ZnAM50 sample). In this study, an adhesion test performed on the ZnAM50 sample indicated that the critical load was 1.35 N. XRD phase analysis confirmed that the obtained coatings included dicalcium phosphate dihydrate (CaHPO4*2H2O). The coatings prepared on the NaAM50 and ZnAM50 samples are effective barriers against the progress of corrosion deeper into the substrate. After 120 h immersion in Ringer’s solution, the volume of the evolved hydrogen was 5.6 mL/cm2 for the NaAM50 and 3.4 mL/cm2 for the ZnAM50 sample.

Evaluation of Corrosive Behavior of Zinc Composite Coating on Mild Steel for Marine Applications

Mild Steel has various forms in which it can be used. It possesses mechanical properties and hence it has found various implementations in many sectors / industries. However, the downside of using mild steel is that it has a high susceptibility to corrosion. There are numerous techniques for protection of mild steel but Zinc electrodeposition techniques is the most preferred method for producing a suitable film coating for the appropriate protection of mild steel. The effect of deposition potential, current, bath composition (including temperature), deposition time and concentration on the structure and crystallinity of the films deposited was systematically studied from various literatures. Introducing zinc into the coating process significantly alters and improves the mechanical and chemical characteristics of mild steel.

Influence of Optical Brightening Agent Concentration on Properties of Cotton Fabric Coated with Photochromic Microcapsules Using a Pad-Dry-Cure Process.

The weak photostability of photochromic dyes applied to textile substrates is one of the disadvantages of the broader use of photochromic dyes in the textile industry. Therefore, the influence of optical brightener concentration on both the photocoloration and photostability of cotton fabric coated with photochromic microcapsules using a pad-dry-cure process, as well as the physical-mechanical properties and colorfastness properties, were studied in this research. Coated samples were subjected to different tests according to valid EN ISO standards; namely mass per unit area, fabric stiffness, breaking force and elongation, air permeability, and different colorfastness properties (rubbing, domestic and commercial laundering, and light). Results showed that the coated fabric had higher mass per unit area, stiffness, breaking force and elongation and lower air permeability compared to uncoated fabric, irrespective of the padding bath composition. Coated fabric has better colorfastness to wet than dry rubbing. The colorfastness to washing decreases with the increased number of washing cycles. The use of optical brightener decreases the photocoloration of coated fabric and increases the photostability of coated fabric after the exposure of samples to a Xenotest apparatus for longer than 12 h.

A study on ion‐exchanged, soda‐lime glass’s residual stress relationship with K+/Na+ concentration

AbstractIn the past, studies have shown that the chemical composition within the exchanged layer could influence both the stress build‐up magnitude and the stress relaxation rate. In this work, a novel approach was proposed to estimate the relationship between the stress relaxation parameters, the dilation coefficient, and the relative K+/Na+ concentration. The proposed method required knowledge of the residual stress profiles, the molten salt bath's temperature and soaking time, and the bath's composition. Based on the analyses performed on various residual stress profiles in ion‐exchanged soda‐lime glass, both the dilation coefficient and the magnitudes of the relaxation time constants were found to consistently decrease with K2O concentration.

Copper-rich Cu–Zn alloy coatings prepared by electrodeposition from glutamate complex electrolyte: Morphology, structure, microhardness and electrochemical studies

In the present work, glutamate ions were applying as a complexing agent in codeposition of Cu-Zn alloy coatings from a non-cyanide acidic sulfate bath at room temperature. The effect of Cu2+/Zn2+ concentration ratios as well as the glutamate ion concentrations on the morphology, structure, and microhardness of the alloy coatings was studied. Electrochemical analyses were implemented using cyclic voltammetry and anodic linear stripping voltammetry. It was found that glutamate ions decrease cathodic overpotential for the reduction of Zn2+ ions and enhances cathodic overpotential for the reduction of Cu2+ ions. Consequently, the simultaneous codeposition of Zn2+ and Cu2+ ions were facilitated and copper-rich Cu–Zn alloy coating was achieved. Characterization of Cu-Zn alloy coatings was carried out using SEM and XRD. The Cu-Zn alloy deposited from the glutamate complex bath consisted mainly of one phase α-CuZn. The morphology of Cu-Zn alloy significantly depends on the Cu2+/Zn2+ concentration ratios, glutamate ion concentrations as well as on the operating conditions as shown by SEM investigation. Moreover, Cu-Zn alloy coating deposited from these baths possesses microhardness ranged from 115 to 250 kg mm−2 depending on the bath composition and the operating conditions.

Influence of Organic Additive Benzene Sulfamide on the Magnetic Behavior of Electrodeposited CoMnP Thin Film Alloys

Electro deposition of CoMnP thin films was carried out for different concentrations of organic additive Benzene sulfamide at a constant bath pH value and for various current density. Magnetic properties such as coercivity, saturation magnetization and the surface morphology were investigated for electrodeposited CoMnP thin films. The characteristics of the CoMnP thin films were found to attain enhanced values, because of the variation in the concentration of the bath solution. The Scanning Electron Microscope (SEM) micrographs of the CoMnP thin films for various bath compositions and additive concentration exhibited different micro cracks. From the X-ray diffraction pattern, structure of the CoMnP alloy films was analyzed and it was found to be Hesagonal Close Packed (HCP) structures with the dominant microstructure and all the co-deposited thin films were found to exhibit Nano crystalline structure. The magnetic properties of the specimens were characterized using Vibrating Sample Magnetometer (VSM). Adhesion and hardness of the electroplated films influenced by organic additive Benzene Sulfamide were also investigated. The magnetic properties were highly influenced by the addition of the organic additive Benzene Sulfamide for various bath composition and bath conditions. Under best condition involving addition of 0.2 M of NaH2PO2 and 2 g/L of Benzene Sulfamide acid at current density 5 mA/cm2 and time of deposition 60 Minutes, the thickness of the film was found to be 4.6 micrometer with coercivity 1500 Oe.

Гидрохимический синтез пленок халькогенидов металлов. Часть 42. Экспериментальная проверка областей осаждения PbSe селеносульфатом натрия и селеномочевиной в присутствии различных лигандов

Calculation of ionic equilibria in the reaction system for synthesis of PbSe thin films was carried out. Three reaction systems containing the following combinations of reagents were considered: sodium citrate with liquid ammonia and sodium selenosulfate (system 1) or selenourea (system 2) used as chalcogenizer, ethilendiamine, sodium acetate and selenourea (system 3).The main lead complex compoundsprevented the fast PbSe formation in system 1 and 2 in region of pH of intensive selenosulfate and selenourea decomposition were hydroxo-citrate complexes. In the system 3 complexes with ethilendiamine and acetate-ions played the most significant role. For evaluating the deposition conditions of the main and impurity phases (metal hydroxides and cyanamides) by thermodynamic calculations taking into account the sizes of critical nucleis, the boundary conditions and regions of formation of PbSe, Pb(OH)2, PbCN2 in the studied reaction systems were found. The calculation results are presented in the form of three-dimensional dependencies in the coordinates “indicator of the initial concentration of the metal salt – pH of the solution – ligand concentration” and “indicator of the initial concentration of the metal salt – pH of the solution – concentration of the chalcogenizer”. Based on the calculations and preliminary experiments, the compositions of the discussed reaction mixtures were formed for the chemical bath deposition of PbSe films, which, in addition to the main components, included a dopant in the form of ammonium iodide. In the synthesis process at a temperature of 353 K (system 1 and 2) for 60 minutes and 308 K for 90 minutes (system 3), using all the studied reaction systems on glass substrates, homogeneous PbSe layers with a thickness of ~500 to ~700 nm were obtained. The ratio between the main elements of Pb and Se in the film varies between 0.98-1.32, and the iodine content is 7-11 at.% depending on the composition of the reaction bath.

Development and characterization of Zn–Ni, Zn–Co and Zn–Ni–Co coatings

ABSTRACTAcidic sulphate baths having ZnSO4 7H2O, NiSO4 7H2O, CoSO4 7H2O and sulphamic acid (SA) were optimized for the deposition of smooth Zn–Ni, Zn–Co and Zn–Ni–Co coatings on mild steel substrate. Bath compositions and deposition conditions were optimized by Hull cell method for maximum efficiency against depositions in corrosion. Faradic efficacy exceeded 90% as the current density increased; increased wt-% of nobler metal content (Ni and Co) in the deposit. Potentiodynamic polarization and electrochemical impedance spectroscopy indicates that the Zn–Ni–Co coating; corrosion resistance was 28 times higher than the Zn–Ni and 21 times higher than the Zn–Co coating. The good corrosion resistance of the Zn–Ni–Co coating was ascribed to its phase structure and the surface morphology. New cheap sulphate baths have been suggested for bright and uniform coating of Zn–Ni, Zn–Co and Zn–Ni–Co and result have been discussed.