Showing papers on "Sodium hypophosphite published in 2006"

Studies on electroless Ni–W–P and Ni–W–Cu–P alloy coatings using chloride-based bath

Abstract: In the present investigation ternary electroless Ni-W-P alloy coatings were prepared using alkaline citrate-based bath. Nickel chloride and sodium tungstate were used as nickel and tungsten sources, respectively, and sodium hypophosphite was used as a reducing agent. Deposits were characterized for their structure, morphology, chemical composition and microhardness. A single peak was obtained in XRD for ternary Ni-W-P alloy. Addition of 3 mM of copper chloride in the bath has resulted in a very smooth quaternary Ni-W-Cu-P alloy. Also, codeposition of copper in ternary alloy has increased the peak sharpness and the calculated grain sizes for ternary and quaternary deposits are 2.5 and 8.8 nm, respectively. XPS studies show that in ternary Ni-W-P deposits from the present bath nearly 60 at.% of tungsten is present in the elemental form, Wlt;supgt;0lt;/supgt;, as compared to that from nickel chloride and sulphate additives bath in which Wlt;supgt;0lt;/supgt; state is only 27 at.%. Addition of copper chloride to the present bath has increased this elemental form by nearly 10 at.% in the quaternary deposit. SEM micrographs show that ternary alloy films are nodular whereas quaternary alloy films are smooth and nodule-free. Microhardness measurements show a marginal difference in the hardness between ternary and quaternary deposits. [All rights reserved Elsevier]

Liquid-phase selective hydrogenation of p-chloronitrobenzene on Ni-P-B nanocatalysts

Abstract: A series of Ni−P−B catalysts were prepared by liquid-phase reduction. Nickel acetate and sodium hypophosphite were mixed in ethanolic solution. The solution of sodium borohydride in excess amount was then added dropwise into the aforementioned mixture to ensure full reduction of the Ni cations. The Ni:P:B ratios in the mother solution was fixed at 1:3:3. These catalysts were characterized by powder X-ray diffraction, nitrogen sorption, transmission electron microscopy, and X-ray photoelectron spectroscopy. The effects of preparation conditions such as temperature, stirring speed, and sheltering gas on the particle size, surface compositions, oxidation states of surface atoms, and catalytic activities of the Ni−P−B catalysts were studied. The catalysts were tested by liquid-phase hydrogenation of p-chloronitrobenzene at 393 K and 1.2 MPa hydrogen pressure in a batch reactor. Raney nickel catalyst was included for comparison. The preparation condition had significant influence on the particle size and surfa...

Electroless deposition of copper in acidic solutions using hypophosphite reducing agent

Abstract: A new bath formulation was developed, which allowed deposition of copper-rich Cu–Ni–P alloys in electroless acidic solutions in the absence of formaldehyde. The reducing agent was sodium hypophosphite. Though cupric ions do not catalyse the oxidation of hypophosphite, we show that, in the presence of a low concentration of Ni(II) species, it is possible, even at low pHs, to induce the reduction of the cupric species. A very strong preferential deposition of copper was observed, which gives Cu–Ni–P layers with copper content up to 97 wt%. The phosphorus content decreased from 13% to 1% with increasing copper content. The plating rate decreased when the copper sulfate concentration in the solution increased. It increased with increasing pH or temperature, but the influence was less pronounced than in alkaline solutions. Compact layers were obtained with a nodular morphology which did not markedly changed with composition.

Hydrogenation of p-chloronitrobenzene on Ni-P-B nanoalloy catalysts

Abstract: A series of nanosized NiPB amorphous alloy catalysts with various concentrations was prepared by chemical reduction of nickel acetate with sodium hypophosphite and sodium borohydride in aqueous solution at 298 K under N 2 curtain gas with vigorous stirring. The catalysts were characterized with inductively coupled plasma-atomic emission spectroscopy, nitrogen sorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalysts were tested for liquid-phase hydrogenation of p-chloronitrobenzene at 1.2 MPa hydrogen pressure, 353 and 393 K reaction temperature, absolute ethanol as a reaction medium, 500 rpm stirring speed, 0.2 M p-CNB, and 2 mmol of Ni catalyst. The initial Ni/P/B molar ratio of starting materials affected the concentration of boron and phosphorus bound to the nickel metal, resulting in a change of surface area, amorphous structure, and hydrogenation activity of the catalyst. The XPS results revealed that boron combined with nickel metal in the NiPB powder donates electrons to nickel metal and that phosphorus withdraws electrons from nickel metal. The sample NiPB(1:3:3) (the values in parentheses are Ni/P/B ratios in the starting materials) prepared at 298 K under N 2 flow with vigorous stirring had the highest surface area of 28.2 m 2 /g. The BET surface area increased with an increase of phosphorus content in the sample. The XPS results revealed that boron could donate electrons to the nickel metal and that phosphorus could accept electrons from the nickel metal in the NiPB catalysts. By regulating the concentrations of boron and phosphorus, one could regulate the electron denisity of nickel, which in turn could influence the activity of the catalyst. The order of activity per weight of the catalyst was NiPB(1:0.3:3) > NiPB(1:1:3) > NiB(1:3) > NiPB (1:3:3). The activities per surface area and turnover frequencies of the catalysts also decreased in the same order. NiPB catalysts prepared with suitable Ni/P/B ratios in the starting materials had higher activities than the NiB catalyst. Small amounts of phosphorus in the NiB catalyst can increase the surface area and turnover frequency. Both are beneficial for promoting the reaction. However, an overdose of phosphorus became a poison for the Ni catalyst.

Electrochemical study on electroless copper plating using sodium hypophosphite as reductant

Abstract: The process of electroless copper plating, using sodium hypophosphite as the reductant and sodium citrate as the chelating agent, was studied using liner sweep voltammetry. The effects of temperature, pH, and concentration of nickel ion on the anodic oxidation of hypophosphite and the cathodic reduction of copper ion were tested. The results indicated that the higher bath temperature accelerated both the anodic and the cathodic processes. The increasing pH value promoted hypophosphite oxidation, whereas it blocked the reduction of the copper ion. The nickel ion not only intensively catalyzed the hypophosphite oxidation but also codeposited with the copper ion to form the Cu-Ni alloy. With regard to its catalytic activity, this alloy enabled the continuation of the electroless copper plating reaction.

Sodium-hypophosphite as a novel reducing agent in the preparation and characterization of silver/silica gel catalysts

Abstract: New catalysts with different loading 2, 5, 8 and 11 (wt.%) silver on silica gel were prepared by chemical reduction method using a sodium-hypophosphite as a novel reducing agent. The catalytic activity was studied through the dehydrogenation of ethanol in a micro catalytic pulse system at 300–450 °C and at hydrogen flow rate 50 mL/min. The structural changes that accompanying the catalysts preparation were detected by X-ray diffraction, differential scanning calorimetry and infrared techniques. Results show that ethanol dehydrogenation was mainly dependent on the silver content and metal-support interaction. In other words, catalyst sample containing 8% Ag was found the most active and selective for acetaldehyde formation and that contain 11% Ag is rich with silver silicate in certain mode. A texture property of the prepared catalysts was investigated.

The Durable Press Finishing of Silk Fabrics by Using 1,2,3,4-Butanetetracarboxylic Acid

Abstract: In this paper, the nonformaldehyde agent 1,2,3,4-butanetetracarboxylic acid was used for durable press finishing of silk fabric. To optimize the finishing, the effects of the amount of sodium hypophosphite, 1,2,3,4-butanetetracarboxylic acid and citric acid, curing temperature and curing time were examined. It was found that the wet wrinkle recovery angle had an obvious improvement from 179° to 273°, and that the finishing had a very small effect to the breaking strength.

Structural characteristics, magnetic nonuniformity, and magnetic intercrystalline interaction in high-coercivity Co-W and Co-P coatings

Abstract: The crystal structure and magnetic properties of Co-W (4–6 at % W) and Co-P (2–5 at % P) coatings produced by electrodeposition at various temperatures (Co-W coatings) or sodium hypophosphite concentrations in an electrolyte (Co-P coatings) are studied. The coatings consist of crystallites having an hcp structure with a [001] and/or a [100] texture depending on the deposition conditions. The structural characteristics, the magnetic nonuniformity, and the magnetic intercrystalline interaction are found to correlate with each other.

Cyanide-free pre-treating solution for electroplating copper coating layer on zinc alloy surface and a pre-treating method thereof

Abstract: A pre-treating solution for electroplating zinc alloy surface contains copper ions, hydroxyl ions, a complexing agent and an additive, wherein the additive is selected from sodium phosphate, sodium hypophosphite, phosphoric acid and dissolvable salts of phosphoric acid. The zinc alloy is dipped in the pre-treating solution and electroplated with a copper coating layer. Then, the zinc alloy is further dipped in a copper sulfate solution for thickening the copper coating layer and lastly coated with an anti-corrosion metal layer. Thereby, zinc alloy has excellent anti-corrosion and anti-wearing efficiency and varnish appearance. Moreover, the pre-treating solution contains no cyanide and thus is low toxic and safe to operator during electroplating and to environment after discharging.

Effect of the nature of a reducing agent on properties of ultradisperse copper powders

Abstract: Ultradisperse copper powders were produced by reduction of copper sulfate with glycerol, L-ascorbic acid, sodium hypophosphite, glucose, and hydrazine. The influence exerted by the nature of a reducing agent on the size-related parameters and physicochemical properties of the powders was studied.

Method of dispersing nanometer silver powder

Abstract: A process for dispersing the silver nanoparticles includes such steps as preparing Ag nanoparticles by liquid-phase reduction method of sodium hypophosphite, immersing the Ag nanoparticles in the dispersing medium (water, absolute alcohol, etc), and ultrasonic dispersing

Regenerating treatment of chemical nickel-plating liquid

Abstract: The invention opened a regenerative processing method of chemical nickelizing. The chemical nickelizing liquid is made up of the nickelous sulfate and the sodium hypophosphite which is the reducing agent, so the sodium sulfate and the sodium hypophosphite would rime from the liquid, so the nickelizing liquid would be self-purification and recover the deposition rate.

Formular of polymer powder chemical nickel-plating and technique thereof

Abstract: A chemical Ni-plating liquid for the polymer powder used for magnetic rheologic liquid or wave absorbing film is prepared from nickel sulfate, sodium citrate, ammonium chloride and sodium hypophosphite. Its plating process is performed at 33-55 deg.C for 1.5-2.5 hr.

Formular and process of polymer powder chemical Co-plating

Abstract: A chemical co-plating liquid for the polymer powder used for magnetic rheologic liquid or wave absorbing film is prepared from cobalt sulfate, potassium sodium tartrate, boric acid, ammonium sulfate, sodium citrate, and sodium hypophosphite. Its plating process is performed at 60-80 deg.C for 1-2 hr.

Aminoacetic acid as complexing agent in baths for electroless deposition of Ni–W–P coatings

Abstract: Ni–W–P alloy coatings were deposited from a bath containing, nickel sulphate (VI), sodium tungstate (VI), sodium hypophosphite, sodium formate, and a complexing agent. The complexing agents were formic acid, acetic acid, lactic acid, succinic acid, malic acid, malonic acid, aminoacetic acid and triethanoloamine. It is shown that Ni–W–P coatings are deposited the slowest when complexing agents with the highest stability constants are used. As the deposition rate increases, i.e. in the presence of less stable complexing compounds, the amount of tungsten in the coating decreases. When aminoacetic acid and citric acid were used, the tungsten content in the coating amounted to ∼2 wt-%, depending on the complexing agent concentration and the pH of the bath.

Production of nanometer silver powder by liquid-phase and solid-liquid separating method

Abstract: A solid-liquid separation method for preparing Ag nanoparticles by liquid phase process includes such steps as preparing nano-class Ag sol by liquid-phase reduction method of sodium hypophosphite, adding regulator in ultrasonic field, laying aside for several hours, and separating Ag nanoparticles by gravitational deposition or vacuum filtering.

Stiffening agent for cotton woven fabrics made from methacrylic acid vinyl acetate methylacrylate terpolymer

Abstract: The emulsion polymerizations of methacrylic acid (MAA), vinyl acetate (VAc), and methyl acrylate (MA) in different VAc/MA molar concentrations (X1, 0.232/0.813; X2, 0.348/0.697; X3, 0.456/0.581; X4, 0.581/0.465; X5, 0.697/0.348) and fixed MAA concentration (0.116 mol) were carried out using sodium dodecyl sulfate (SDS; 34 mmol) as emulsifier and potassium persulphate (K2S2O8; 37 mmol) as initiator at 70 °C for 6 h in semicontinuous reaction mode. The average molecular weights (Mn, Mw) and the molecular weights distributions were determined using gel permeation chromatography (GPC). All terpolymers prepared showed monomodal molecular weights distributions. Glass transition (Tg), crystallization (Tc), and melting (Tm) temperatures and thermal stability of the prepared terpolymers were determined using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), respectively. The elongation percentage at rupture, tensile strength and accelerated thermal aging were determined for X1–5 terpolymers, as functions of the molar composition in the emulsion polymerization feed. The terpolymers prepared, X1–5 terpolymers, were tested as stiffening agents for cotton woven fabrics through crosslinking to cellulose, using sodium hypophosphite monohydrate (NaH2PO2·H2O) as catalyst. The effect of X1–5 compositions upon the stiffening efficiency was discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2006

Method for preparing nickel phosphor alloy nanowire

Abstract: The invention disclosed the method for preparation of nickel-phosphor alloy nanometer line. The method comprises the following step: sensitizing the aluminum oxide mould with stannochlor solution, activating the aluminum oxide mould with palladium bichloride solution, then putting the aluminum oxide mould into the liquid containing sodium hypophosphite and nickel sulfate, and getting the nickel-phosphor alloy nanometer line. The method is no electrochemical deposition, so the operation is simple, the cost is low, and the nickel-phosphor alloy nanometer line is dense and homogeneous.

Chemical plating solution for preparing long-lasting self-lubricating composite coating and chemical plating method thereof

Abstract: The invention relates the preparing long-acting self-lubricating composite deposite chemical plating liquid, comprising the following characters: 20-35g/L nickel sulfate, 30-65g/L sodium tungstate, 18-25g/L sodium hypophosphite, 20-38g/L ammonia sulfate, 90-110g/L sodium citrate, 3-8ml/L lactic acid, 6-12ml/L 60% politef suspending liquid, 8-15g/L molybdenum disulfide, and 10-20mg/L stabilizing agent. The method comprises the following steps: cleaning and activating the surface of work, putting the work into chemical plating liquid at 8-9.5 PH and 85-92Deg.C for 10-60 min. The politef and molybdenum disulfide made by the said method has the advantages of homogeneous thickness, good association, high hardness, strong blocking resistance and good corrosivity.

Glass fiber binder for aircraft insulation

Abstract: Glass fiber compositions are provided in the form of mats comprising a binder of thermoplastic polymer or other non-hazardous insulation material which resists high temperatures such as 2,000° F. for long periods. A binder for a fiber insulation mat utilizes a high molecular weight resin polyacrylic acid polymer mixed with a catalyst such as sodium hypophosphite and triethonal to provide a bond. A silicone provides water repellency, a surfactant controls surface tension, and ammonia or an acid adjusts the pH and a silane.

A manufacture method of electroconductive fiber for electron-wave interception

Abstract: A method for manufacturing electroconductive fibers for intercepting electron waves is provided to grant conductivity to various base fiber bodies, realize an antibacterial effect and an aesthetic appreciation effect, and effectively intercept electromagnetic waves. A base fiber body is etched by 50-100g/l of sodium hydroxide or 1%(v/v) of a surfactant at 60-80 deg.C for 5 minutes. The etched base fiber body is washed by water. The washed base fiber body is washed by a 10% hydrochloric acid solution for 20-50 minutes. The washed base fiber body is washed by water. The base fiber body is treated with a preliminary catalyst by a 7-12% hydrochloric acid solution. The base fiber body is deposited in a solution manufactured by adding 3N hydrochloric acid of a normal temperature to a mixture including 0.4 weight% of palladium chloride and tin chloride, at 20-50 deg.C for 10-30 minutes. The base fiber body is washed by water. The base fiber body is activated by a 13% sulphuric acid solution to activate electroless deposition eduction. The base fiber body is washed by water. The base fiber body is coated with a solution having pH 8.0-9.5, consisting of 10g/l of sulphuric acid nickel, 7.5g/l of sodium hypophosphite, 15g/l of sodium citrate, at 40-45 degrees. The coated base fiber body is washed by water. The base fiber body is treated with a pH 11.5-13.0 electroless copper chloride plating solution consisting of 2.3g/l of copper chloride, 9g/l of sodium hydroxide, 4g/l of formalin, and 0.125M of chelate. The treated base fiber body is washed to remove residual chemicals and alien substances. The base fiber body is dried.

Ytterbium added chemical nickel phosphorus plating liquid and its use method

Abstract: A chemical plating liquid for plating NiP layer on the surface of workpiece is prepared from nickel sulfate, sodium hypophosphite, lactic acid or hydroxyacetic acid, sodium acetate, potassium iodite and Yb. Its application method includes such steps as using sodium hydroxide solution or diluted sulfuric acid solution to regulate pH=4.5-5.5, heating to 85-92 deg.C, deoiling the workpiece, and immersing the workpiece in it.

Spectrophotometric determination of palladium(II) based on its catalytic effect on the reduction of azure I by sodium hypophosphite

Abstract: A catalytic-spectrophotometric method for the determination of traces of palladium(II) is proposed. The reaction is based on the catalytic action of palladium(II) on the reduction of azure I (λmax = 647 nm) by sodium hypophosphite. The various variables affecting the sensitivity were studied, and a study of interfering ions was also carried out. The reaction gave a detection limit of 4.3 ng/mL palladium(II) and good reproducibility with a relative standard deviation of 1.53–1.98% in the palladium(II) concentration range 40–200 ng/mL. The method yielded another linear range (5–40 ng/mL) when using slightly different conditions. In this case, the detection limit was 0.78 ng/mL palladium(II), and the relative standard deviation for ten replicate analyses of 20 ng/mL palladium(II) was 2.05%. The method was applied to the determination of palladium in a sample of activated charcoal.

Radical Reaction of Sodium Hypophosphite with Terminal Alkynes: Synthesis of 1,1-Bis-H-phosphinates.

Abstract: The room-temperature radical addition of sodium hypophosphite to terminal alkynes produces the previously unknown 1-alkyl-1,1-bis-H-phosphinates in moderate yield. The reaction is initiated by R3B and air and proceeds under mild conditions in an open container. The bissodium salts precipitate spontaneously from the reaction mixtures, thus providing a simple purification procedure and the opportunity for multigram synthesis. The 1,1-bis-H-phosphinate products are novel precursors of the biologically important 1,1-bisphosphonates.

Process and properties of nickel coated copper powder used in electronic industry

Abstract: By electroless nickel plating,nickel coated copper powder with relatively higher performance/price rate and good electromagnetic screen ability was prepared using sodium hypophosphite as reducer and flaky copper power of different granularity.The influences of copper powder's diameter and nickel content on the performance of the nickel coated copper powder were discussed.The results show that electroless nickel plating is easier to be realized for the copper powder with greater granularity,while the electric resistance of nickel coated copper powder increases with decreasing copper powder's granularity;The color and resistance of nickel coated copper powder become light and smaller respectively with reduced nickel content.SEM photos reveal that the nickel coated copper powder has satisfactory morphology and flaky degree.The nickel coated copper powder obtained with 30% of nickel content is an ideal electromagnetic screen material because of its low phosphor content,a practical value of composition content consistent with theoretical value,and good loose loading density and conductivity.