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

Ahmad, Jamal; Asami, K.; Takeuchi, Akira; Inoue, Akihisa

doi:10.2320/matertrans.44.705

Cited by 17 publications

(15 citation statements)

References 20 publications

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“…It has been reported for Ni-W system 30) that the addition of sodium hypophosphite to electroplating solution causes a sudden drop in tungsten content of the alloy as well as in cathode current efficiency (or deposition rate at constant current density). Therefore, in order to study the effect of sodium hypophosphite on Ni-Fe-W system, one should use experimental conditions corresponding to the preparation of an alloy with high tungsten content.…”

Section: Ni-fe-w-p Alloysmentioning

confidence: 99%

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

et al. 2003

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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 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%.

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Section: Ni-fe-w-p Alloysmentioning

confidence: 99%

“…30) It was observed that sodium hypophosphite, which was used to introduce phosphorus in the system, had negative effect on the tungsten content of the alloys. The tungsten content was decreased sharply by the addition of sodium hypophosphite.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2003

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“…For example, the mechanical properties of the Ni-W-P amorphous alloy thin film deposited on substrates by electro-plating was reported. 12) Hashimoto et al reported that the Ni-Cr-P-B quaternary amorphous alloys possessed excellent corrosion resistance. 13) Recently, we found that the Ni-Cr-P-B amorphous alloy had a wide super-cooled liquid region, ÁT x .…”

Section: Introductionmentioning

confidence: 99%

Production of Ni65Cr15P16B4 Metallic Glass-Coated Bipolar Plate for Fuel Cell by High Velocity Oxy-Fuel (HVOF) Spray Coating Method

Kim

Yamaura

Shimizu³

et al. 2010

Mater. Trans.

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In this study, the newly designed bipolar plate for proton exchange membrane fuel cells (PEMFC) was produced by spray-coating the Ni 65 Cr 15 P 16 B 4 metallic glassy alloy on Al plate. The Ni 65 Cr 15 P 16 B 4 metallic glass was adopted as a coating material because of its excellent corrosion resistance and the high velocity oxy-fuel (HVOF) spray coating was used for the metallic glass deposition on the Al plates having a bipolar plate flow field.The corrosion resistance of the Ni 65 Cr 15 P 16 B 4 glassy alloy film produced by the HVOF spray-coating was studied under simulated PEMFC environments. As a result, the Ni 65 Cr 15 P 16 B 4 glassy alloy film showed lower corrosion current density than the high-corrosion-resistant stainless steel SUS316L. Then, the electricity generation tests with the single cell having the Ni 65 Cr 15 P 16 B 4 glassy alloy-coated bipolar plates produced in this study were conducted. As a result, the single cell with the metallic glass-coated bipolar plates showed very high I-V performance as well as the cell with the carbon bipolar plates. The long time durability tests for 24 h were also conducted at the constant current density of 200 mAÁcm À2 . As a result, the single cell with the glass-coated bipolar plates showed no voltage drop during the test. So, it was found in this study that the Ni 65 Cr 15 P 16 B 4 glassy alloy-coated bipolar plate produced by the HVOF spray-coating have a potential for practical use for the fuel cells.

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“…It is worthmentioning that nanocrystalline alloys exhibit extremely high corrosion resistance comparable to extremely homogeneous amorphous counterparts, [14][15][16][17][18][19] and extra-ordinary high strength with reasonable ductility depending on the grain size and deformation mechanism. 20,21) Electrochemical study and DC plating in the bath based on zinc and nickel chlorides and boric acid without any addition has not yet been focused upon to the best of our knowledge.…”

Section: Introductionmentioning

confidence: 99%

Deposition of Nanocrystalline Zinc-Nickel Alloys by D.C. Plating in Additive Free Chloride Bath

et al. 2007

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Nanocrystalline zinc-nickel alloy coatings were electro-deposited in chloride bath containing ZnCl 2 (50-200 gL À1 ), NiCl 2 .6H 2 O (50-200 gL À1 ) and H 3 BO 3 (40 gL À1 ) at 45 C. The initial alloy composition, as investigated by voltammetry, chronopotentiometry or EDX analysis, exhibited a pronounced dependence on the composition of plating bath. However, the alloy composition tended to approach an upper limit of 18 atomic percent when deposits grew thicker, for most of the plating bath compositions. The process was clearly the anomalous codeposition, which was considered to be due to the formation of an adsorbed layer of Zn(OH) 2 containing nickel cations, as an intermediate product, whose composition determines the composition of the electro-deposited alloy. The electro-deposited coatings comprised of single-phase structure of -phase (Ni 5 Zn 21 ) for about 12-18 atomic percent nickel and a mixture of -and -phases (hcp) for nickel atom percent below 8. The grain size decreased from about 50 nm to 20 nm with decrease in nickel content away from the stoichiometric composition of Ni 5 Zn 21 along with a decrease in hardness from about 450KHN to 150KHN. The decrease in hardness with a decrease in grain size seems attributable to the grain boundary sliding as predominant deformation mechanism. Anodic dissolution of the alloys involved pronounced dezincification, forming -phase (fcc) that dissolved at the end.

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

Cited by 17 publications

References 20 publications

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

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

Production of Ni<SUB>65</SUB>Cr<SUB>15</SUB>P<SUB>16</SUB>B<SUB>4</SUB> Metallic Glass-Coated Bipolar Plate for Fuel Cell by High Velocity Oxy-Fuel (HVOF) Spray Coating Method

Deposition of Nanocrystalline Zinc-Nickel Alloys by D.C. Plating in Additive Free Chloride Bath

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