Concentration Of Sodium Hypophosphite Research Articles

Cotton Dyeing and Antibacterial Finishing Using Agricultural Waste by an Eco-friendly Process Optimized by Response Surface Methodology

In this study, Berberis vulgaris L. wood as an agricultural waste was used for dyeing and functional finishing of cotton. To facilitate the attachment of natural dye, citric acid was used to create carboxylic acid functional groups on cotton fibers. The process of crosslinking of cotton fabric with citric acid was optimized in order to obtain the maximum dyeability with the cationic natural dye. The effects of three important factors including citric acid concentration, sodium hypophosphite concentration and curing temperature on the color strength of the dyed samples with woods of barberry tree were analyzed by response surface methodology and the optimum conditions for obtaining the highest color strength was obtained. The crosslinking of citric acid on cotton fibers was confirmed by FTIR spectroscopy. The dyed sample prepared under the optimum conditions of crosslinking showed good wash and light fastness properties besides very good antibacterial activity against gram-negative and gram-positive bacteria.

Composite coatings of nickel-vanadium-phosphorus-nitride boron

The effect on the micro hardness of nickel - vanadium coatings from the concentration of sodium hypophosphite in the range 10-30 g / l, the concentration of boron nitride from 0 to 50 g / l, and from the temperature in the range of 50 - 90 ° C was studied. The influence of these factors on the rate of coating, the appearance of the coating and the thickness of the coatings was researched. The effect of heat treatment regimes on the micro hardness of coatings is studied. Regressions equations are obtained that allow calculating the micro hardness of coatings when the composition, the temperature of the electrolyte and the heat treatment temperature change. The wear resistance of the obtained composite coating is determined. The composite coating of nickel-vanadium-phosphorus-boron nitride can be recommended for increasing the resistance of deforming tools operating at temperatures up to 600°C.

Modelling of surfactants and chemistry for electroless Ni-P plating

ABSTRACTIn this work, the effects of the chemical formulation in an electroless nickel phosphorus electrolyte on the physical and mechanical performance of the obtained coating were evaluated. The study not only paid particular attention to the concentration and type of surfactant (anionic, cationic and non-ionic) but also investigated the effect of pH and concentration of sodium hypophosphite in the electrolyte. A three-level Box–Behnken factorial design related to response surface methodology was employed to model the effect of the mentioned parameters and optimise the properties of the coating. Two models fitted with experimental data obtained from microhardness and thickness measurement of the Ni-P coatings. The optimum conditions were determined at pH = 5 with 32 g L−1 sodium hypophosphite and 1.5 g L−1 anionic surfactant. According to the derived models, this formulation would give a Ni-P coating with a microhardness of 1080 Hv and a thickness of 23 µm.

Parametric Optimization of Process Parameters on the Response of Microhardness of Electroless Ni-P Coating

The present work deals with the synthesis of chemically deposited nickel–phosphorous (Ni–P) coating on copper substrate. The process parameters are optimized for maximum hardness based on L[Formula: see text] Taguchi orthogonal design with three process parameters, viz., bath temperature, concentration of nickel Sulphate (a nickel source) and concentration of sodium hypophosphite (a reducing agent), respectively. This is considered and fitted into an L[Formula: see text] orthogonal array (OA) to find out the optimized condition for improved hardness of the coating. The optimized results were obtained from 35[Formula: see text]g/L of Nickel Sulphate, 20[Formula: see text]g/L of Sodium Hypophosphite and 90∘C of temperature. Analysis of variance (ANOVA) was performed to determine the significance of the individual process parameters. ANOVA showed that the factor Nickel Sulphate, the interaction between Sodium Hypophosphite and Temperature were significant in determining the hardness of the coating deposited in the optimized condition. The surface morphology, compositional and phase structure analysis of optimized sample are conducted with the help of scanning electron microscope (SEM), energy-dispersive X-ray analysis and X-ray diffraction (XRD) analyzer, respectively.

Electrolytic Codeposition of Nickel and Phosphorus from Methanesulfonate Electrolyte

The characteristics of Ni–P alloy electrodeposition from a methanesulfonate electrolyte have been investigated. It has been found that the phosphorus content of the alloy increases with increasing the concentration of sodium hypophosphite in the electrolyte and reducing the electrodeposition current density. A mechanism of codeposition of nickel and phosphorus has been suggested. It is shown that phosphorus was formed by electrochemical reduction of hypophosphite anions and their disproportionation at a catalytically active surface of a nickel cathode. It has been shown quantitatively that the most likely path for the formation of phosphorus through the electrochemical mechanism is the direct electrochemical reduction of a hypophosphite anion to atomic phosphorus. The rate of phosphorous formation from hypophosphite anions is dependent on the concentration of hydrogen ions in the near-electrode layer. Therefore, the phosphorus content of the coatings obtained from the methanesulfonate electrolyte is slightly decreased as compared with that from the sulfate electrolyte which exhibits higher buffering properties. It has been revealed that codeposition of nickel and phosphorus reduces the kinetic difficulties of electrochemical reduction of the nickel ions. This might be due to an increased near-electrode concentration of nickel hydroxyl complexes discharging at the cathode, which is the result of an increased near-electrode pH caused by the reactions involving hypophosphite anions and hydrogen ions.

Examining the effect of electrosynthesis conditions on the Ni-P alloy composition

The Ni–P alloys are widely used as catalysts, magnetic and wear resistant materials. Properties of the nickel-phosphorous alloys are defined by the composition. A highly regulated technique to obtain the alloys with specified composition is the electrosynthesis. It is a relevant task to establish dependences of the alloy composition on the process conditions. In the present work we examined the influence of electrolysis parameters on the Ni–P alloy composition, obtained from the methanesulfonate and sulfate electrolytes. It is shown that an increase in the concentration of sodium hypophosphite, acidity and temperature of the electrolyte increases phosphorus content in the alloy. It was established that when carrying out the electrosynthesis under galvanostatic mode, a change in the alloy composition is predetermined by the rate of phosphorus formation. Atomic phosphorus is formed as a result of the course of two reactions. There occurs the electroreduction and disproportionation of hypophosphite-anion involving hydrogen ions. An increase in the concentration of hydrogen ions in the near-electrode layer contributes to an increase in the rate of phosphorus formation and growing phosphorus content in the alloy. That is why the alloys with a higher content of phosphorus are formed at lower pH indices of the electrolyte and at higher temperature. It was established that weak buffer properties of the methanesulfonate electrolyte are responsible for the lowered phosphorus content in the synthesized alloy. High pH index in the near-electrode layer reduces the rate of phosphorus formation. Established regularities might prove very useful when designing new technologies of the Ni–P alloy electrosynthesis of specified composition from the methanesulfonate electrolyte.

Characteristics of electrodeposition of Ni and Ni-P alloys from methanesulfonate electrolytes

The characteristics of electrodeposition of Ni-P alloys from a methanesulfonate electrolyte have been investigated. Ni-P alloys electrodeposited from an electrolyte containing 0.03–0.12moldm−3 of sodium hypophosphite, produce uniform, smooth, and well adherent to the substrate deposits. Phosphorus content of the alloy increases with an increase in the sodium hypophosphite concentration in the electrolyte and a decrease in the electrodeposition current density. Nickel-phosphorus alloys have a refined surface structure with small grains closely adjacent to each other. Ni-P alloys obtained from the methanesulfonate electrolyte at pH 3, have gloss levels of up to 20%. The coatings exhibit higher internal stresses and hardness, which increase with an increased concentration of sodium hypophosphite in the electrolyte. A decrease in the electrolyte pH increases the phosphorus content of the deposits and enhances the properties studied. The phosphorus content of the coatings obtained from a methanesulfonate electrolyte is lower than in the coatings deposited from a sulfate electrolyte under the same conditions. However, the deposits produced from the methanesulfonate electrolyte are characterized by higher values of gloss, hardness and internal stresses. This is due to the fact that along with phosphorus incorporated into the coating, the deposit structure is distorted by nickel hydroxide incorporated to the deposit during the electrolysis. The methanesulfonate electrolyte has lower buffering properties and, correspondingly, a higher amount of nickel hydroxide dispersion is formed in the near-electrode layer. The experimental data indicate that, in spite of lower phosphorus content, Ni-P alloys deposited from a methanesulfonate electrolyte have better physical-mechanical properties than those deposited from a sulfate electrolyte.

Magnetic properties of electrodeposited amorphous nickel–phosphorus alloys

The influence of the sodium hypophosphite concentration in a sulfate–citrate electrolyte of nickel plating on the phosphorus content in electrodeposited amorphous Ni–P alloys was analyzed. The effect of the thermal treatment on the magnetic properties (coercive force and specific magnetization) of the obtained Ni–P alloys was considered; the Curie temperatures of the alloys were determined.

Electrodeposited Fe-P nanowire arrays in hard-anodic aluminum oxide templates with controllable magnetic properties by thermal annealing

The highly ordered uniform amorphous Fe-P alloy nanowire arrays are fabricated by potentiostatic electrodeposition in hard-anodic aluminum oxide (H-AAO) templates with diameter and pore distance about 110 nm and 265 nm, respectively. The deposited Fe-P nanowire arrays gradually change from crystalline to amorphous phase as the phosphorus content in the nanowire arrays increases. The phosphorus content and nanowire growth rate are sensitive to the applied potential and sodium hypophosphite concentration in electrolyte. Subsequently, the as-deposited amorphous Fe-P alloy nanowire arrays are annealed with different temperature. And the original and annealed samples reveal different crystallographic structures and magnetic properties. The results show that both the coercivity and squareness have been improved significantly, while the magnetic anisotropy become weak with the increasing of annealing temperature, which mainly attributes to the competition of shape anisotropy, stress anisotropy and the strengthening of magnetocrystalline anisotropy.

Conductive nickel/carbon fiber composites prepared via an electroless plating route

In this work, nickel/carbon fiber composites with excellent conductivity were successfully prepared by an electroless plating method in alkaline media, in which sodium hypophosphite was used as reducing agent. The composition, microstructure, electrical, and magnetic properties of samples were investigated by XRD, SEM, VSM, and four-probe meter techniques, respectively. It was found that the volume of aqueous ammonia and concentration of sodium hypophosphite played important roles on the microstructure of nickel coatings. The composites with compact and uniform nickel layer on the surface of carbon fiber possessed face-centered cubic phase, and the volume resistivity could reach 1.49 × 10−3 Ω cm. In addition, magnetic hysteresis measured at room temperature demonstrated that the nickel-coated carbon fiber composites showed ferromagnetic behavior with saturation magnetization (M s ) and coercivity (H c ) of 5.2 emu/g and 144.9 Oe, respectively.

Capacitive Performances of Reduced Graphene Oxide Hydrogel Prepared by Using Sodium Hypophosphite as Reducer

AbstractThe hydrogels of reduced graphene oxide (rGOHGs) have been synthesized through treating GO with various concentrations of sodium hypophosphite (NaH2PO2) under hydrothermal condition. The results reveal that the structure of rGOHGs changes along with the increase of the concentration of NaH2PO2. The rGO sheets prepared with low concentration of NaH2PO2 exhibit more crimples and larger specific surface area than those prepared with high concentration of NaH2PO2. The measurements of the capacitive performances of rGOHGs reveal that the rGOHGs prepared with low concentration of NaH2PO2 possess larger specific capacitance (Cs) than that prepared with high concentration of NaH2PO2 at low cyclic voltammetry scan rates. However, the rGOHGs prepared with high concentration of NaH2PO2 possess larger Cs at high scan rates, more stability and better high‐rate capability than those prepared at low concentration. It is believed that the structures and properties of rGOHGs can be adjusted by controlling the concentration of NaH2PO2 according to the requirement.

Parameter optimization for electroless Ni–W–P coating

Ternary Ni–W–P coatings were electrolessly plated on an Al alloy substrate. The influence of the main parameters including: the concentrations of sodium hypophosphite and sodium citrate; bath temperature; bath pH; and selected bath stabilizers on the composition of coatings was investigated by an orthogonal experimental method. The results indicated that by controlling the bath composition and process parameters, the percentage of W and P in the coating could be optimized while using a constant amount of sodium tungstate. Furthermore, the presence of stabilizers in the bath had a significant influence on the W and P content of the coatings. The parameters controlling the deposition of W by electroless method were found to be similar with those affecting W deposition in electroplating. Induced co-deposition of W on catalytic Ni surface was suggested to explain the experimental results.

Parametric optimization of corrosion and wear of electroless Ni-P-Cu coating using grey relational coefficient coupled with weighted principal component analysis

This research article considers optimization of the four process parameters based on corrosion and wear of electroless Ni-P-Cu coatings. The major characteristics indexes for performance selected to evaluate the processes are corrosion potential (E corr), corrosion current density (I corr) and wear. Among the corresponding four process parameters the first three are coating parameters, viz. concentration of nickel sulphate, concentration of sodium hypophosphite, concentration of copper sulphate and the fourth one is post deposition heat treatment temperature. The corrosion property, i.e. E corr and I corr, has been studied by potentiodynamic polarization test and the wear is measured in terms of wear depth by DUCOM TR-25 multi-tribotester with block on roller arrangement. In this study, the process is intrinsically combined with multiple performance indexes so that grey relational analysis is specially adopted to determine the optimal combination of coating parameters. Moreover, the weighted principal component analysis (WPCA) is applied to evaluate the weighting values corresponding to various performance characteristics so that their relative importance can be properly and objectively described. From the analysis the optimum combination of parameters for corrosion property and the optimum combination of parameters for corrosion and wear together are obtained. The chemical composition, surface morphology and phase behaviour are investigated using energy dispersive X-ray analysis, scanning electron microscopy and X-ray diffraction analysis, respectively.

Effect of Sodium Hypophosphite Content to the Deposition Rate, Structure and Magnetic Properties of Electroless Deposited Ni-P Alloy

The deposition kinetics, structure and magnetic properties of electroless deposited films Ni-P were investigated depending on the amount of sodium hypophosphite in the electroless bath. It was found that the film deposition rate is linear and unambiguously varies with the hypophosphite content from 2 to 13 g/l and from 23 to 25 g/l. The deposition rate varies widely in the hypophosphite concentration range from 13 to 23 g/l. The films are composed of amorphous Ni-P phase and fcc Ni-P solid solution with phosphorus content from 1 to 4 at.% P according to X-ray diffraction. The partial amount of amorphous phase is increased with concentration of sodium hypophosphite. The ferromagnetic resonance field is independent on the concentration of sodium hypophosphite, which assumes to be result from the laminated allocation of the amorphous and fcc phases in the film.

Optimization of Electroless Ni–P–Al2O3 Composite Coatings based on Multiple Surface Roughness Characteristics

Electroless Ni–P–Al2O3 composite coatings are popular due to their excellent hardness, friction and wear resistance. The present study tries to investigate the influence of coating process parameters on the surface roughness of electroless Ni–P–Al2O3 composite coating with the help of Taguchi analysis. The different surface roughness parameters considered are, center line average roughness (Ra), root mean square roughness (Rq), skewness (Rsk), kurtosis (Rku), and mean line peak spacing (Rsm). Three parameters, namely, concentration of nickel sulphate as a nickel source, concentration of sodium hypophosphite as reducing agent, and concentration of Al2O3 particles as concentration of second phase particles are considered and fitted into an L27 orthogonal array to find out the optimized condition to minimize the surface roughness of the coating. It is observed that concentration of Al2O3 particles have the most significant influence on Ni–P–Al2O3 composite coating and concentration of reducing agent has moderate influence. The compositional, micro-structural, and phase structure analyses are conducted with the help of energy-dispersive X-ray analysis, scanning electron microscope, and X-ray diffraction analyzer, respectively.

Effect of Process Parameters on Microhardness of Ni-P-Al2O3 Composite Coatings

Electroless Ni-P-Al2O3 composite coatings have found wide range of applications due to their high hardness and wear resistance. The present study triesto investigate the influence of coating process parameters on the microhardness of electroless Ni-P-Al2O3 composite coating with the help ofTaguchi analysis. Four parameters, namely, concentration of nickel sulphateas a nickel source, concentration of sodium hypophosphite as a reducing agent, concentration of Al2O3 particles as concentration of second phase particles, and annealing temperature, are considered and fitted into an L27 orthogonal array to find out the optimized condition for improvedhardness of the coating. The optimized condition is found to yield about 20.47% improvement in hardness of the coating comparedto the initial condition. The significance of the process parameters and their interactions on the hardness of electroless Ni-P-Al2O3 composite coating isstudied with the help of analysis of variance, which revealed that annealing temperature and concentration of second phase particles (Al2O3 particles) have significant influence on the hardness characteristics of electroless Ni-P-Al2O3 composite coating. The compositional, microstructural, andphase structure analyses are conducted with the help of energy-dispersive X-ray analysis, scanning electron microscope, and X-raydiffraction analyzer, respectively.

Process Optimization Studies Based on BP Neural Network in Electroless Plating of Ni-Fe-Co-P on Carbon Fiber

It presents a method to predict and optimize the electroless plating process, and to compare the predictive ability of the network to the experimental results. It combined with the neural network and orthogonal experiment and used a small step searching method to optimize the chemical process of plated Ni - Co-Fe-P on carbon fiber within the scope of the process parameters, got more optimized process recipe: the temperature is 88°C, ratio of the main salt concentration is 0.46, the concentration of sodium citrate is 46 g/L, and the pH value is 9.03, the concentration of sodium hypophosphite is 24 g/L. Through validating with experiments, the error between them is 2.39%, the linear correlation between the method of calculation and experimental program of the target is very good, and the correlation coefficient R =0.99943 which indicated that the training results are reliable and the BP neural network optimizing the process recipe is indeed feasible.

Flame retardancy and UV protection of cotton based fabrics using nano ZnO and polycarboxylic acids

This research mainly deals with a novel flame-retardant and UV-protection for cellulosic fabrics using ZnO nanoparticles. We present the preparation and application of ZnO nanoparticles. The size of the prepared nanoparticles was analysed using dynamic light scattering (DLS). The application of nano ZnO on cellulosic fabrics (cotton 100% and cotton/cotton polyester 65/35%) was achieved by using different polycarboxilic acids (succinic acid [SA] and 1,2,3,4-butane tetracarboxilic acids [BTCA]) with sodium hypophosphite (SHP) as catalyst through conventional pad-dry-cure method. The effect of concentration of SHP on the physical properties, flammability and UV-protection of cross-linked fabrics are investigated. The effect of concentration of zinc oxide nanoparticles and the effect of curing temperature were also investigated. The results revealed the importance of SHP in increasing the flame-redundancy of the treated cellulosic fabrics.

Electroless copper-phosphorus coatings with the addition of silicon carbide (SiC) particles

Cu-P-silicon carbide (SiC) composite coatings were deposited by means of electroless plating. The effects of pH values, temperature, and different concentrations of sodium hypophosphite (NaH2PO2·H2O), nickel sulfate (NiSO4·6H2O), sodium citrate (C6H5Na3O7·2H2O) and SiC on the deposition rate and coating compositions were evaluated, and the bath formulation for Cu-P-SiC composite coatings was optimised. The coating compositions were determined using energy-dispersive X-ray analysis (EDX). The corresponding optimal operating parameters for depositing Cu-P-SiC are as follows: pH 9; temperature, 90°C; NaH2PO2·H2O concentration, 125 g/L; NiSO4·6H2O concentration, 3.125 g/L; SiC concentration, 5 g/L; and C6H5Na3O7·2H2O concentration, 50 g/L. The surface morphology of the coatings analysed by scanning electron microscopy (SEM) shows that Cu particles are uniformly distributed. The hardness and wear resistance of Cu-P composite coatings are improved with the addition of SiC particles and increase with the increase of SiC content.

Ultraviolet resistant/antiwrinkle finishing of cotton fabrics by sol‐gel method

AbstractNano titanium dioxide (TiO2) sols were prepared by sol‐gel method with tetrabutyl orthotitanate (TBOT) as precursors, citric acid (CA) as inhibitors. Ultraviolet resistant capacity of finished cotton fabrics are greatly improved with good wrinkle‐resistance, whiteness and tensile strength as well. The optimum molar ratio for preparing nano‐TiO2 sols in this study is n[C2H5OH] : n[H2O] : n[CA] : n[HCl] : n[TOBT] = 20 : 6 : 1.2 : 0.025 : 1, at ambient temperature. Particle size distribution analysis of the sol reveals that the curve is right tailed with an average diameter of 72.8 nm. Factors affecting the performance of finished cotton fabrics by TiO2 sols, such as concentration of sodium hypophosphite (SHP), triethanolamine (TEA) in finishing bath, curing temperatures and time lengths were investigated by orthogonal experiments. The optimum finishing results can be obtained with 3% SHP, 3% TEA, curing at 165°C for 3 min. Aggregated nano‐TiO2 particles on surfaces of finished cotton fibers both washed and unwashed were investigated by high resolution cold field emission scanning electron microscope and energy dispersive X‐ray spectrometer. Esterification crosslinking between CA and cotton fibers were also demonstrated through infrared spectra. After a five‐time's wash, ultraviolet protection factor of finished cotton fabrics with nano‐TiO2 sols is up to 117.42 and dry crease recovery angles increase by 30.2° with slightly improved whiteness, while the breaking strength decreases by 18.8%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011