Showing papers on "Sodium hypophosphite published in 1999"

Preparation and Characterization of Electroless Ni-P and Ni-P-Si3N4 Composite Coatings

Abstract: SUMMARYThe present work pertains to the study of electroless Ni-P and Ni-P-Si3N4 composite coatings. The deposits are obtained from a proprietary high phosphorus electroless nickel plating bath, comprising nickel sulphate, sodium hypophosphite, complexing agents and stabilizers. The maximum weight percent of Si3N4 incorporated in the electroless deposit is obtained at a concentration of 10 g/l in the bath. The electroless Ni-P deposits having 0%, 2.01%, 5.81% and 8.10% of Si3N4, respectively, obtained from baths containing 0, 2, 5 and 10 g/l of Si3N4, are characterized by optical microscopy, XRD and TEM. Hardness is found to increase with the incorporation of Si3N4 at all heat treatment temperatures studied. Also hardness increases with an increase in weight percent of Si3N4 incorporated in the deposit. The analyses of the composite coatings by XRD and TEM reveal that the inclusion of Si3N4 particles does not change the amorphous nature of the Ni-P matrix.

Ni–Zn–P alloy deposition from sulfate bath: inhibitory effect of zinc

Abstract: Electroless Ni–Zn–P alloy deposition from a sulphate bath, containing sodium hypophosphite as reducer, was investigated. To increase the plating rate, the deposition parameters were optimized. The effect of process parameters (T, pH and [Zn2+]) on the plating rate and deposit composition was examined and it was found that the presence of zinc in the bath has an inhibitory effect on the alloy deposition. As a consequence, the percentage of zinc in the electroless Ni–Zn–P alloys never reaches high values. Using cyclic voltammetry the electrodeposition mechanism of Ni–Zn–P alloys was investigated. It was observed that the zinc deposition inhibits the nickel discharge and, as a consequence, its catalytic activity on hypophosphite oxidation. It was also found that increase in temperature or pH leads to the deposition of nickel rich alloys.

Influence of additives on the formation of unsaturated PCAs produced during durable‐press curing with citric acid

Abstract: To impart durable-press properties to cellulosic material, the fabrics have been treated with a finishing bath containing a polycarboxylic acid in combination with an appropriate catalyst When citric acid (CA) was applied as crosslinking agent discoloration of the fabric was observed Special additives were included into the formulation to improve the whiteness index Isocratic HPLC was used to identify and quantify the unsaturated polycarboxylic acids that are produced during the curing process of CA-treated cotton fabrics The influence of different catalysts (sodium hypophosphite, sodium dihydrogen phosphate, disodium hydrogen phosphate, tetrasodium pyrophosphate, trisodium phosphate) and of various types of additives, such as triethanol amine (TEA), W,/V,bis(hydroxy-ethyljglycine (BICINE), boric acid and polyethylene glycol 200 (PEG 200), on the content of CA and the amount of unsaturated PCAs in the wash liquor and on the fabric has been investigated A significant reduction of the unsaturated polycarboxylic acids was observed when an additive was incorporated into the pad bath

Hydrogen evolution, incorporation and removal in electroless nickel composite coatings on aluminium

Abstract: The mechanism of electroless nickel deposition involves generation of hydrogen which can be entrapped in the NiP layer. In this study hydrogen evolution in several electroless composite coatings, that is, NiP–X (X=SiC, Al2O3 and boron particles), deposited on an aluminium (6063-T6) substrate, was investigated by the solid extraction method. It was found that particle codeposition can promote hydrogen occlusion in the layers, a fact correlated with the adsorption capacity and affinity of particles towards water or hydrogen itself. Hydrogen removal efficiency from coatings, after heat treatment, increased with the applied temperature (130, 160 and 190 °C for 1.5h each). For the same heat treatment (190 °C for 1.5h), most composite coatings showed lower removal efficiencies (35–54%) compared to NiP layer (80%) and, as the amount of hydrogen in the composite coating increased, its removal efficiency decreased.

Nucleation of Metals on Aluminum by Laser Irradiation and the Effect on Ni‐P Electroless Deposition

Abstract: The mechanism of direct Ni-P electroless deposition on aluminum by pulsed yttrium aluminum garnet (YAG) laser irradiation in Ni 2+ /H 2 PO 2 solution was investigated by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) with energy-dispersive X-ray (EDX) analysis. Aluminum specimens covered with porous anodic oxide films were irradiated with a pulsed YAG laser in solutions containing Pd 2+ , Cu 2+ , Ni 2+ , or Ni 2+ /H 2 PO 2 ions, and then localized Ni-P electroless plating was attempted at the laser irradiated area in Ni 2+ /H 2 PO 2 solution. It was found that laser irradiation in solutions containing Pd 2+ , Cu 2+ , or Ni 2+ ions causes the deposition of small metallic particles of Pd, Cu, or Ni at the laser-irradiated area on the aluminum surface which was exposed to the solution after removal of anodic oxide film. The deposition of the metals is due to a redox reaction between the aluminum substrate and the Pd 2+ , Cu 2+ , or Ni 2+ ions. During laser irradiation in Ni 2+ /H 2 PO 2 solution, Ni-P and Ni were deposited by redox reactions between Ni 2+ and H 2 PO 2 as well as between Ni 2+ and Al. Palladium and nickel (Ni-P) particles deposited during the laser irradiation acted as catalytic centers for the subsequent Ni-P electroless plating, while Cu particles did not promote the electroless plating.

Ft-Ir and Ft-Raman Spectroscopy Study of the Cyclic Anhydride Intermediates for the Esterification of Cellulose: Ii. Formation of Anhydrides Catalyzed By Sodium Hypophosphite

Abstract: A five-membered cyclic anhydride is the reactive intermediate of polycarboxylic acids for esterifying cellulose. In our previous research, we found that polycarboxylic acids in a crystalline state start to form 5-membered cyclic carboxylic anhydrides when the temperature reaches the vicinity of their melting points, and that hydrogen bonding between carboxylic acid groups prevents the formation of the cyclic anhydride intermediates at lower temperatures. In this research, we studied the formation of cyclic anhydride intermediates by 1,2,3,4-butane-tetracarboxylic acid (BTCA) and itaconic acid (IA) in the presence of sodium hypophosphite (NaH 2 PO 2 ) ' We found that NaH 2 PO 2 weakens the hydrogen bonding between the carboxylic acid groups of BTCA. In the presence of NaH 2 PO 2 , BTCA forms the cyclic anhydride at temperatures significantly lower than its melting point. NaH 2 PO 2 also reduces the temperatures required for the formation of the anhydride intermediate of IA on cotton fabric. The catalysis for the formation of anhydride intermediates by NaH 2 PO 2 contributes to the acceleration of esterification of cotton cellulose by polycarboxylic acids.

Nucleation of polyamides in the presence of hypophosphite

Abstract: The present invention provides polyamide compositions comprising a polyamide, nylon 2,2, and a phosphorous-containing whitening agent having Formula (I), wherein R is hydrogen, an alkyl group with 1 to 6 carbons, a cycloalkyl group with 5 to 6 carbons, or a phenyl or methylphenyl aromatic group, and M is hydrogen or a metal. In a preferred embodiment, the polyamide is nylon 6,6 (polyhexamethylene adipamide) and the phosphorous-containing whitening agent is a hypophosphorous acid or a metal hypophosphite. Sodium hypophosphite is especially preferred. The polyamide compositions of the present invention have improved molding cycle times, and are tough, white and color-stable.

Method of manufacturing nickel hypophosphite by the electro-membrane technique

Abstract: The method of manufacturing nickel hypophosphite from a solution of hexahydrated nickel sulfate and a solution of monohydrated sodium hypophosphite by an electro-membrane technique, consists: a) in introducing respectively the hexahydrated nickel sulfate solution and the monohydrated sodium hypophosphite solution into each of two dilution circuits of four-compartment electrodialysis cells formed by alternating stacks of cationic and anionic homopolar membranes in an electrodialysis apparatus having an anode and a cathode that are insoluble; b) in applying an electrical current from the anode to the cathode without regulating the pH of the solutions contained in the dilution and concentration circuits but regulating the electricity supply, either in voltage or in current; and c) in recovering a hexahydrated nickel hypophosphite solution from one of the concentration circuits.

Additive for soil improvement

Abstract: PROBLEM TO BE SOLVED: To provide an additive for soil improvement capable of improving the flowability of a soil cement and improving excavational properties and workability due to the retention of flowability and further reducing the amount of surplus soil to be discharged by incorporating a carboxylic acid based polymer to be obtained by allowing a predetermined amount of a hypophosphorous acid (salt) to be present in polymerizing an acrylic acid based monomer as an additive for soil improvement. SOLUTION: In an apparatus equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel and a nitrogen inlet tube are charged 150 pts.wt. water and heated to 100 deg.C in a nitrogen stream. Then, while maintaining the water at 100 deg.C under stirring, 460 pts.wt. monomer aqueous solution obtained by dissolving 353.5 pts.wt. acrylic acid and 17.3 pts.wt. sodium hypophosphite in water and 90 pts.wt. initiator aqueous solution obtained by dissolving 5.6 pts.wt. ammonium persulfate in water are continuously added dropwise over three hours, respectively. Further, the reaction solution is maintained at the same temperature for one hour to complete the polymerization. After cooling, the reaction solution is neutralized by the addition of 471 pts.wt. 40% sodium hydroxide and diluted with water to obtain an acrylic acid polymer.

Electroless gold plating method

Abstract: PROBLEM TO BE SOLVED: To improve the adhesive strength between an electroless nickel plating film and solder at the time of soldering and to improve the yield in the soldering stage by specifying the ten point average roughness of the surface of an electroless nickel plating substrate film formed on a stock in which an electroless gold plating film formed. SOLUTION: An electroless nickel plating substrate is formed on a stock, and, an electroless gold plating film is formed on the electroless nickel plating substrate. At this time, the ten point average roughness of the surface of the electroless nickel plating film to be formed on the stock is controlled to 0.5 to 1.5 μm. Moreover, the thickness of the electroless nickel plating film to be formed on the stock is preferably controlled to 7 to 15 μm. Furthermore, the electroless nickel plating film can be formed on the stock with an electroless nickel plating soln., as a reducing agent, using sodium hypophosphite added with 0.01 to 0.05 mL/L sulfur compd. as a stabilizer. Moreover, by executing chemical or mechanical polishing, the ten point average roughness of the surface can be controlled to the range.

Electro-membrane process for preparing nickel hypophosphite

Abstract: The process describes a double decomposition reaction between monohydrated sodium hypophosphite and hexahydrated nickel sulfate to form the hexahydrated nickel hypophosphite by electrodialysis. The process consists of: (a) introduction, respectively, of nickel sulfate and sodium hypophosphite solutions in each of two dilution circuits (D1, D2) of four compartment electrodialysis cells, formed by alternate stacking of cationic (C) and anionic (A) homopolar membranes, the electrodialyzer comprising an insoluble cathode and insoluble anode; (b) application of an electric current from anode to cathode without pH regulation of the solutions in the dilution and concentration circuits, but with regulation of the electricity supply by voltage or current intensity; and (c) recovery of hexahydrated nickel hypophosphite solution from one of the concentration circuits (C2).

Manufacturing method of an electric conduction fiber

Abstract: Disclosed is a method for fabricating an electro-conductive fiber, which comprises the steps of treating a basic fiber composed of filaments of polyester or acrylic series with 2 to 3 gr of sodium hydroxide and non-ionic surfactant at a temperature of 30 to 40 DEG C for about five minutes, washing sufficiently the treated fiber in a hot bath of 60 to 70 DEG C, etching the washed fiber with a liquid solution mixed with hydrochloric acid of 50 ml and nitric acid of 10 ml at room temperature for about thirty minutes, immersing the etched fiber in a liquid solution mixed with palladium chloride of 2 gr and tin chloride of 2 gr added with hydrochloric acid (HCl) at a temperature of 20 to 50 DEG C for about ten minutes after washing, washing to remove the tin from the fiber, and immersing the fiber in a liquid solution of sodium hydroxide of 50 gr at room temperature to remove residual tin, immersing the fiber in a liquid solution mixed with cupric sulfate of 20 gr, sodium hydroxide of 40 gr and rosolic salt of 160 gr added with 37 % formalin at a temperature of 40 to 50 DEG C for 10 to 15 minutes, and immersing the fiber in a liquid solution mixed with sulfate nickel of 20 gr, citric acid of 15 gr and sodium hypophosphite of 30 gr at a temperature of 30 to 40 DEG C for about ten minutes (nickel formed with a thickness of about 0,2 mu m). In this way, the traditional fiber is coated with a very thin film of electrical conductivity, which is formed around the fiber nucleus of non-electrical conductivity, so that the fiber has electrical conductivity without losing the desired physical properties of the traditional fiber.

Review on sodium hypophosphite production

Abstract: The general situation、main industrial process research trend of sodium hypophosphite industry at home and abroad are described. The impurities removing in production of sodium hypophosphite is focused in the paper.

Hard magnetic layer, useful for electronic memories, is electrodeposited from an electrolyte containing cobalt, optionally nickel, carboxylic acid, sodium hypophosphite and ammonium sulfate

Abstract: Hard magnetic layer is electrodeposited, from an electrolyte containing cobalt, optionally nickel, carboxylic acid, sodium hypophosphite and ammonium sulfate. In an electrolyte and process for electro-deposition of hard magnetic layers, the electrolyte has the composition 1.5-20 g/l Co , 0-10 g/l Ni , 20-75 g/l carboxylic acid(s) or salt(s), 10-60 g/l sodium hypophosphite and 20-100 g/l ammonium sulfate and is used at 0.1-2.0 A/dm cathodic current density, 40-95 deg C and pH 7.1-8.5.