Showing papers on "Sodium hypophosphite published in 2003"

Electroless Ni–Co–P ternary alloy deposits: preparation and characteristics

Abstract: Electroless Ni–Co–P ternary alloy deposits were prepared by varying the metallic ratio and were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and vibration sample magnetometer. The plating rate of electroless Ni–Co–P deposits is a function of concentration of sodium hypophosphite, pH of the plating bath, plating time and the metallic ratio. With increase in metallic ratio, the cobalt content of the deposits increases with a simultaneous decrease in the nickel content, while the phosphorus content decreases slightly. The electroless Ni–Co–P deposits of the present study are amorphous in their as-deposited condition. The DSC trace exhibits three distinct exothermic peaks, corresponding to the relaxation of lattice strain during the phase separation, the phase transformation of amorphous phase to nickel and nickel phosphide phases and the transformation of metastable phases to stable nickel phosphide phase. The XRD pattern of electroless Ni–Co–P deposits confirms the formation of Ni, Ni5P2, Ni12P5 and Ni3P phases during annealing at 300 and 400 °C for 1 h. Thermomagnetic study exhibits the Curie transition of nickel and non-stoichiometric Ni3Co based alloys. Being amorphous in nature, the electroless Ni–Co–P deposits exhibit soft magnetic characteristics. The saturation magnetization, remanence and coercivity increase with cobalt content of the deposit.

The Deposition Characteristics of Accelerated Nonformaldehyde Electroless Copper Plating

Abstract: The deposition process of an electroless copper plating solution using sodium citrate as the main complexing agent and sodium hypophosphite as the reducing agent has been investigated. The deposit composition, structure, and catalytic activity for the oxidation of hypophosphite during the process have been investigated. Formamidine disulfide (fd) has been shown to accelerate the deposition rate of the electroless plating just as it does with electroless plating solutions using N-(2-hydroxyethyl)ethylenediaminetriacetic acid trisodium salt hydrate (HEDTA) as the complexing agent. For solutions with the mole ratio of 42, the deposition rate decreased with time and terminated after 90 min plating because the surface catalytic activity of the deposit had decreased with thickness. A copper deposit with total thickness of 6.48-6.59 μm was obtained after 90 min plating. The decrease in the deposition rate with time was mitigated by decreasing the mole ratio, holding the concentration of copper ions constant. An optimized electroless copper plating process with sustained deposition rate with time and high metal conductivity was developed. The bath was used in a fully additive high density wiring process. © 2003 The Electrochemical Society. All rights reserved.

Electroless nickel plating solutions

Abstract: This invention relates to aqueous electroless nickel plating solutions, and more particularly, to nickel plating solutions based on nickel salts of alkyl sulfonic acids as the source of nickel ions. The plating solutions utilize, as a reducing agent, hypophosphorous acid or bath soluble salts thereof selected from sodium hypophosphite, potassium hypophosphite and ammonium hypophosphite. The electroless nickel plating solutions of the invention are free of added nickel hypophosphite, and free of alkali or alkaline earth metal ions capable of forming an insoluble orthophosphite.

Combination of a hydroxy-functional organophosphorus oligomer and a multifunctional carboxylic acid as a flame retardant finishing system for cotton: part ii. formation of calcium salt during laundering

Abstract: Multifunctional carboxylic acids, such as 1,2,3,4-butanetetracarboxylic acid (BTCA), were used to bond a hydroxy-functional organophosphorus oligomer (FR) to cotton fabric in the presence of a catalyst, such as sodium hypophosphite (NaH2PO2). Previously, it was found that the cotton fabric treated with FR and BTCA showed a high level of phosphorus retention after one home laundering cycle. However, the flame retardant properties quickly deteriorated as the number of home laundering cycles was increased. In this research, it was found that the free carboxylic acid groups bound to the cotton fabric form an insoluble calcium salt during home laundering, thus diminishing the flame retardant properties of the treated cotton fabric. It was also found that the free carboxylic acid groups on the treated cotton fabric were esterified by triethanolamine (TEA), and that the formation of calcium salt on the fabric was suppressed by the esterification of the free carboxylic acid groups by TEA. The cotton fabric treated with BTCA and the hydroxy-functional organophosphorus oligomer significantly improved its flame retardance when a new catalyst system consisting of hypophosphorous acid (H3PO2) and TEA was used in the system.

Monodisperse polymer/metal composite particles by electroless chemical deposition: Effect of surface functionality of polymer particles

Abstract: Micron-sized polymer particles were coated with layers of nickel compounds by plating electrolessly in the presence of aqueous solutions of nickel chloride, sodium hypophosphite, sodium citrate, and ammonium chloride at elevated temperature. The uniform functional polymer particle could be obtained by seeded polymerization. To investigate the effect of surface functionality on the conditions for nickel deposition, the polymer particle was functionalized with the thiol group. From morphological observation, it was found that the mode of nickel deposition was greatly dependent on the surface functionality of the polymer particle. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 420–424, 2003

High Strength Ni-Fe-W and Ni-Fe-W-P Alloys Produced by Electrodeposition

Abstract: Ni-Fe-W alloys were produced by electrodeposition from an ammoniacal citrate bath having nickel sulphate, ferric sulphate and sodium tungstate as sources of nickel, iron and tungsten, respectively. The alloys prepared at low current densities have nanocrystalline structure, while those prepared at high current densities are amorphous. X-ray diffraction results show that the structure changes gradually from nanocrystalline to amorphous phase with an increase of current density. As the current density increases, tungsten content increases while iron content decreases. The hardness of the alloys increases with increasing tungsten content. The best mechanical properties among all the alloys are obtained for 51Ni29Fe-20W alloy prepared at 600 A/m 2 . Effect of sodium hypophosphite on the composition of the alloys produced at 2000 A/m 2 was also studied. Addition of hypophosphite causes a decrease in tungsten content of the alloys. Further increase in the hypophosphite content causes a decrease of both iron and tungsten contents and an increase of phosphorus and nickel contents. For the alloys deposited from solutions containing sodium hypophosphite more than 0.03 mol/L, the total molar content of tungsten and phosphorus remains constant at 20 at%.

Mechanism of Stabilizer Acceleration in Electroless Nickel at Wirebond Substrates

Abstract: This paper examines the mechanism of stabilizer concentration at electroless nickel wirebond electrodes. A one-step activation protocol was first achieved on copper substrates using acetic acid and dimethylamineborane. Thereafter nickel multilayers were grown onto the substrates using nickel sulfate heptahydrate as the source of nickel, sodium hypophosphite as the reducing agent, acetic acid as the complexing agent, and thiourea/lead acetate as the stabilizing agent. The morphology of the nickel layers and the effective concentration of the stabilizer were determined using quartz crystal microbalance, gravimetric techniques, and energy-dispersive X-ray analysis (EDX). The plating rate was obtained by measuring the thickness of the Ni-plated using X-ray fluorescence spectroscopy. It was found that lead acetate completely inhibited the plating, and a bimodal distribution was observed as the concentration of the thiourea was varied. We proposed a mechanism for the effect of stabilizer in electroless Ni baths. This mechanism was confirmed using Fourier Transform Infrared and EDX measurements. © 2003 The Electrochemical Society. All rights reserved.

High strength Ni-Fe-W and Ni-Fe-W-P alloys produced by electrodeposition : Nano-Hetero Structures in Advanced Metallic Materials

Abstract: Ni-Fe-W alloys were produced by electrodeposition from an ammoniacal citrate bath having nickel sulphate, ferric sulphate and sodium tungstate as sources of nickel, iron and tungsten, respectively. The alloys prepared at low current densities have nanocrystalline structure, while those prepared at high current densities are amorphous. X-ray diffraction results show that the structure changes gradually from nanocrystalline to amorphous phase with an increase of current density. As the current density increases, tungsten content increases while iron content decreases. The hardness of the alloys increases with increasing tungsten content. The best mechanical properties among all the alloys are obtained for 51Ni-29Fe-20W alloy prepared at 600A/m 2 . Effect of sodium hypophosphite on the composition of the alloys produced at 2000 A/m 2 was also studied. Addition of hypophosphite causes a decrease in tungsten content of the alloys. Further increase in the hypophosphite content causes a decrease of both iron and tungsten contents and an increase of phosphorus and nickel contents. For the alloys deposited from solutions containing sodium hypophosphite more than 0.03 mol/L, the total molar content of tungsten and phosphorus remains constant at 20 at%.

Effect of Sodium Hypophosphite on the Structure and Properties of Electrodeposited Ni-W-P Alloys

Abstract: Amorphous and nanocrystalline Ni-W-P alloy films have been prepared by electrodeposition. The effect of sodium hypophosphite in the bath is important in determining the W and P contents of the alloy. The alloys prepared in the bath containing more than about 0.15 mol/L of sodium hypophosphite are only Ni-P alloys containing high P contents (>21% (at)) and no W at all. However, as the sodium hypophosphite content is decreased, the W content in the alloy increases and reaches about 20% (at) with decreasing P content to about 1% (at) at 6 x 10 -4 mol/L of sodium hypophosphite. The alloys containing high P contents are amorphous, while those containing high W contents have a nanocrystalline phase with apparent grain size of 2.3 nm at 20% (at) W content. These nanocrystalline alloys show high hardness values up to about 780 MVH.

Nickel phosphorus chemical plating method of neodymium iron boron permanent magnet material

Abstract: In the invention, the sodium hypophosphite is as the reducing agent of the bath, nickel sulfate as the main salt, with the complexing agent, accelerating agent and stabilizing agent being added. The ultrasonic chemical plating and second chemical plating method are adopted that utilizes the mechanical energy of the ultrasonic vibration, making the bath deposit nickel and phosphor under the catalysis of the metal surafce and the chemical reduction method controlled. The plating procedure includes the steps of edge rounding, oil removal, rust removal, activation, chemical plating and post treatment. The multiple complexing, accelerating and stabilizing agents raises the stability of the bath. The plating speed is adjustable. The even, compact nickel and phosphor plating layer covers the surface of the base body of powder metallurgical material so as to increase the service life of the material and provide wide application area.

Oxidation of phosphorus compounds by Fenton's reagent.

Abstract: In the present work a Fenton's treatment for the oxidation of a phosphorous compounds mixture, simulating a match manufacturing industry wastewater, were studied. Experimental tests were performed on three sample solutions at a phosphorus concentration of 250, 500 and 750 mg/l. In each solution an equal amount of sodium phosphite and sodium hypophosphite was dissolved. The investigation of pH, temperature and reagents ratio on the oxidation rate led to the individuation of the optimal process operating conditions. The results show that Fenton's reagent provides a powerful conversion to phosphate of the phosphorous solution. In particular at pH=3.5 and 20 degrees C a residual concentration of non oxidized phosphorus in compliance with the Italian regulation limits for industrial wastewater disposal. Tests performed on sample solution of 500 mg/l P and 750 mg/l P by adding hydrogen peroxide and bivalent iron in three sequential steps led to similar reaction efficiencies to tests carried out adding both Fenton's reagents in one step, but with a remarkably lower reagents consumption.

Electrochemical investigations on the influence of electrolyte composition of Watts baths with special regard to throwing power

Abstract: The influence of a variety of substances on technically relevant parameters of a nickel electroplating electrolyte (Watts bath) has been investigated. Special attention has been paid to the throwing power (TP), as well as visual appearance, current efficiency and codeposition of foreign atoms. Systems reported in the literature (e.g., inorganic salts to increase conductivity or complexing agents to increase polarization) were compared with typical reducing agents normally used in electroless Ni deposition. The mechanism of TP improvement in the case of sodium hypophosphite and dimethylamine-borane has been examined with the electrochemical quartz crystal microbalance (EQCM). Using the EQCM it was shown that there is a synergistic effect between the electrochemical and electroless deposition process. In addition, the activation energy of the latter was determined from temperature dependent measurements.

Commercial process for electroplating nickel-phosphorus coatings

Abstract: An aqueous bath for electroplating NiP coatings comprising, generally, a solution containing nickel salts, either a mixture of nickel sulfate and nickel chloride or an all nickel chloride source, sodium hypophosphite and boric acid Thiourea is added to an all chloride bath solution for decorative applications or other applications requiring enhanced brightness Upon dissolution of the bath constituents, the bath pH is adjusted up to a value of 35 to 45 with sodium hydroxide and maintained for at least 15 minutes at or above room temperature, preferably in the range of 40° to 50°C, which prevents the oxidation of the hypophosphite anions The bath pH is then reduced to the operating range of 20 to 30, preferably 22 to 26

Metallic plating liquid

Abstract: A metal plating liquid by means of redox reaction contains water as solvent, nickel sulfate and/or nickel chloride for providing nickelousions, sodium hypophosphite as reducer, sodium citrate as complexing agent and acrylthiourea as stabilizer. Its advantages are no environmental pollution, low cost and high adhesion and resistances to rust and corrosion of plated layer.

Amorphous Co-Ni-P Alloys with High Saturation Magnetization Produced by Electrodeposition

Abstract: The composition, structure and magnetic properties of high cobalt-containing Co-Ni-P alloys have been examined by controlling electrodepostion parameters. The alloys were deposited at 323 K from an electroplating solution consisting of nickel and cobalt chlorides and sodium hypophosphite. The current density and pH of the solution were controlled to determine the conditions of forming amorphous films. The alloys prepared at a current density of 150 A/m 2 and pH of 5.20 include both amorphous and crystalline phases. The increase of pH to above 5.20 results in the formation of amorphous alloys without crystalline phase. The conditions of 220 A/m 2 for current density and 5.24 for pH were optimum to prepare the amorphous alloy at the highest deposition rate of 5.19 x 10 -5 kg/m 2 /s. These amorphous alloys exhibited high saturation magnetization up to 1.3T with coercivity of about 20 kA/m.

Process for preparing high-performance Ni-P alloy solution for chemical plating

Abstract: A high-performance soloution for chemical plating of Ni-P alloy contains primary salt (nickel sulfate and sodium hypophosphite), composite complexing agent (complexon, citric acid, lactic acid, sterculic acid and butanedioic acid), composite buffer (boric acid and sodium acetate), and composite stabilizer (sodium thiocyanate, ammonium mobybdenate and lead nitrate). Its advantages are high stability and high anticorrosion performance of its plated layer; and the plated layer can be applied with secondary plating.

Catalyst system and method for preparing flame resistant materials

Abstract: Presently, multifunctional carboxylic acids, such as 1,2,3,4-butanetetracarboxylic acid (BTCA) are used to bond a hydroxyl-functional organophosphorous oligomer to cotton fabric in the presence of a catalyst, such as sodium hypophosphite (NaH 2 PO 2 ). However, the free carboxylic acid groups bound to the cotton fabric form a calcium salt during home laundering, thus diminishing the flame retardant properties of the treated cotton fabric. Disclosed herein is a new catalyst system consisting of hypophosphorous acid (H 3 PO 2 ) and a nitrogen-containing organic base such as triethanol amine (TEA). When the catalyst system is present together with the polycarboxylic acid, TEA esterifies the free carboxylic acid groups under curing conditions, thus reducing calcium concentration on the fabric during home laundering. It also provides nitrogen-phosphorous synergism to enhance the flame retardant performance of the organophosphorous compound. The cotton fabric treated with BTCA and the hydroxyl-functional organophosphorous oligomer in the presence of this new catalyst system demonstrate flame retardant properties superior to that treated with NaH 2 PO 2 as a catalyst.

Products and preparation of chemical plating liquid for chemical coating of nickle-phosphorus alloy

Abstract: A chemical plating liquid for the Ni-P alloy layer is prepared from nickel sulfate, propionic acid, sodium hypophosphite, butanedioic acid, sodium citrate, potassium iodide, lactic acid, polyethanediol and distilled water through proportioal mixing, and regulating pH=4.8-5.2 by ammonia water. Its advantages are high stability and long service life.

Chemical nickel plating solution of aluminium based chassis

Abstract: A chemical Ni-plating solution for Al-base casing contains proportionally nickel sulfate, sodium hypophosphite, citric acid, succinic acid, triethanolamine and sodium acetate. It is applied at 60-90 deg.C and pH=3-13. The plated casing features high electric conductivity, resistance to electromagnetic interference and hardness, and high antiwear and anticorrosion performance.

2 Double electroless nikel plating method by pre-treatment process of magnesium and magnesium alloy

Abstract: PURPOSE: A double electroless nickel plating method by pretreatment process of magnesium and magnesium alloy are provided to remove fine surface defects and improve corrosion resistance of moldings of magnesium and magnesium alloy used in various electric, electronic and mechanical parts. CONSTITUTION: The double electroless nickel plating method by pretreatment process of magnesium and magnesium alloy comprises the processes of washing the material to be plated three times by dipping a material to be plated of magnesium or magnesium alloy in an aqueous solution comprising a metal emulsifier; washing the material to be plated twice by dipping the material to be plated into an aqueous solution in which hydrates of ammonium fluoride and hydrofluoric acid are mixed; washing three times the material to be plated by dipping the material to be plated into an aqueous solution in which hydrate of potassium pyrophosphate is dissolved; washing the material to be plated twice by dipping the material to be plated into an aqueous solution in which hydrates of ammonium fluoride and hydrofluoric acid are mixed; washing three times the material to be plated by dipping the material to be plated into an aqueous solution in which hydrate of potassium pyrophosphate is dissolved; dipping the material to be plated into an electroless nickel plating solution in which a mixed solution of nickel sulfate, ammonia water, ammonium fluoride, lactic acid, succinic acid and sodium hypophosphite is adjusted to pH of 7.8 to 8.2 by ammonia water of 75 to 80 deg.C; and performing electroless plating for 40 minutes by dipping the primarily plated material into an electroless nickel plating solution in which a mixed solution of nickel sulfate, ammonia water, ammonium fluoride, lactic acid, succinic acid and sodium hypophosphite is adjusted to pH of 4.8 to 5.2 by ammonia water of 75 to 80 deg.C.

Method for machines parts of iron-carbon alloys combined cover producing

Abstract: A method for the machine parts of the iron-carbon alloys combined cover producing includes plating of a chemical nickel-cobalt-phosphor cover from a solution containing a lemon acid sodium, a sodium hypophosphite, an ammonia, the cobalt and nickel salts, and a diffusive chrome-plating in a powder environment. The chemical cover is applied at the temperatures 80-90°С with density of the solution loading 4 dm2/l during 45 min. As the cobalt salt the cobaltous chloride is used, an as the nickel salt - nickel chloride. Additionally the solution contains an ammonium chloride. After the solution applying the diffusive chrome-plating is performed at 1000-1050°С during 5 hours, and in the process at the temperature of 800°С reaching an isothermal keeping is provided during 1 hour.

The Electroless Plating Ni-Fe-P Alloy and Its Voltammetric Behavior

Abstract: Electroless Ni_Fe_P alloy deposition from an alkaline bath, containing sodium hypophosphite as reducer, boric acid as buffer agent and sodium citrate as complexing agent, was investigated. To increase the plating rate and to inprove the bath stability, the deposition parameters were optimized. The effects of process parameters (pH,temperature and mole ratio of [Fe 2+ ]/([Ni 2+ ]+[Fe 2+ ]) on the plating rate and deposit composition were examined and it was found that the presence of ferrous sulfate in the bath has an inhibitory effect on the alloy deposition. As a consequence, the per_centage of iron in the electroless Ni_Fe_P alloys never reaches high values which is lower 20.0%. Using cyclic voltammetry the electrodeposition mechanism of Ni_Fe_P alloys was investigated. It was observed that the presence of ferrous sulfate in the bath decreases the deposition rate and the iron doesn′t catalyst on the oxidation of hypophosphite. However, the increase in temperature or pH leads to improving the deposition rate.

Electroless nickel deposition on mild steel by using a new bath formulation and its characterization

Abstract: A new bath formulation has been developed to prepare the Ni-P deposits on mild steel substrates. The alkaline bath formulation contains NiCl 2 as a Ni source and sodium hypophosphite as reducing agent. The Ni-P alloy withhigher phosphorus content was obtained by using this new bath formulation. The uniform deposits of Ni-P (1.98-12.5) were obtained. The change in rate of deposition with time, temperature and pH was studied. The effect of concentration of nickel and reducing agent on the deposition was investigated. The samples obtained were characterized by using SEM, XRD, DSC and ICP-OES techniques. The Ni-P deposits were amorphous in nature and upon heat treatment in between 300 to 450°C, it changes to crystalline Ni 3 -P phase. The phosphorus content of the deposits increases with the deposition time and highest P content is obtained on the samples prepared at 3 h time.

Electroless nickel plating solution

Abstract: PROBLEM TO BE SOLVED: To provide nickel plating solution which produces an acceptable nickel deposit over an extended period of time at a high plating rate. SOLUTION: The aqueous electroless nickel plating solution comprises (A) a nickel salt of an alkyl sulfonic acid, and (B) hypophosphorous acid or a bath soluble salt thereof selected from sodium hypophosphite, potassium hypophosphite and ammonium hypophosphite, wherein the solution contains no added nickel hypophosphite, and is free from alkali or alkaline earth metal ions capable of forming insoluble orthophosphite. COPYRIGHT: (C)2004,JPO

Nickle-phosphorus alloy plating liquid and coating method

Abstract: A Ni-P alloy plating liquid contains Ni salt (0.5-6 wt.%), sodium hypophosphite (0.5-4), complexing agent (0.5-6), water (87-92) and stabilizer (rest). Its plating process includes such steps as ultrasonic treating to workpiece for 2-4 min for removing rust and oil, washing, immersing in weak acid for acid frosting, activating, washing, plating at 45-95 deg.C for 0.5-6 hr, washing, baking in high-temp oil at 90-180 deg.C. Its advantages are no poison, no corrosion, and high resistance to wear, corrosion and high temp for plated workpiece.

Durable press finishing of tussah fabric with citric acid

Abstract: In this article,effects of durable press finishing of tussah silk fabrics treated with citric acid(CA) and no-iron resin were comparedBy L9(3)4 orthogonal test,the best blending ratio of citric acid combined finishing agent and other parameters were determinedThat is,citric acid 7%,sodium hypophosphite 5%,triethylamine 2%,formate 6%,predrying at 80C for 5 min,curing at 160t for 1 minThe wrinkle recovery angle (WRA) of treated tussah silk fabrics reaches 290 while the strength retention is 85 %