Ni-W alloy

Note that essentially the same behavior as for the Ni-P alloy deposition was observed in electrodeposition of other iron-group alloys, such as Co-W and Ni-W alloys. Namely, the deposition current in the presence of Na2W04 (the W-source of the Co-W and Ni-W alloys) started to flow at a more positive potential than in the absence of Na2W04, indicating that the electrodeposition of the Co-W and Ni-W alloys occurs by essentially the same mechanism as that of the Ni-P alloy, suggesting the presence of a general mechanism for the induced co-deposition of these alloys. 

As mentioned above, the Ni-P (Co-W, Ni-W) alloy deposition current in the presence of the P-source (W-source) starts to flow at a more positive potential than in... 

Fig. 7.50 Magnetic hyperfine field //hf in Ni-W-alloys at the W-site as a function (a) of the tungsten concentration and (b) of the average magnetic moment (from [238])...

Attempts to electrodeposit pure tungsten date approximately 140 years back. Nowadays, however, it is commonly accepted that this metal cannot be deposited alone from its aqueous solutions, but can be codeposited as an alloy, exhibiting a unique combination of properties. For example, Ni-W alloys have good mechanical properties (e.g., high tensile strength and premium... 

Although there has been no direct evidence for the formation of the above mixed-metal complex, there are ample experimental observations supporting the assumption that it is indeed formed and serves as the precursor for deposition of the Ni-W alloys. These indications include ... 

For induced codeposition of Ni-W alloys, we concluded that the precursor for deposition of the alloy is a mixed-metal complex of the type [(Ni)(HWO4)(Cit)] ". This complex is formed from a nickel citrate complex (cf., Eq. 50) and a tungstate citrate complex [(WO4)(Cit)(H)] . It may be somewhat surprising that the nega-... 

Plating of alloys of Mo was studied intensively in recent years by Landolt and his co-workers. It was shown that in fonnation of Ni-Mo alloys, the rate of deposition of Mo (i.e., the partial current density for deposition of this metal) is controlled by the concentration of Ni in solution. This is consistent, of course, with the idea that the precursor for deposition of the alloy is a mixed-metal complex, as proposed for Ni-W alloys by Gileadi et al. It is also expected in view of the similarity of the chemistry of W and Mo ions in aqueous solutions. However, the mixed metal complex for Ni-Mo alloy deposition was assumed to be [NiCit(Mo02)]ads The most important difference between the assumed mixed-metal complexes are that in the case of W the complex is in solution, while in the case of Mo it is assumed to be adsorbed on the surface. More-... 

Obradovic, M.D., Stevanovic, R.M., and Despic, A.R. (2003) Electrochemical deposition of Ni-W alloys from ammonia-citrate electrolyte. J. Electroanal Chem., 552, 185-196. 

Y. Giga, Y. Kimoto, Demonstration of an inverse Hall-Petch relationship in electrodeposited nanocrystalline Ni-W alloys through tensile testing. Scripta Mater. 55(2), 143-146 (2006)... 

H. Somekawa, T.G. Nieh, K. Higashi, Instrumented indentation properties of electrodeposited Ni-W alloys with different microstructures. Scripta Mater. 50(11), 1361-1365 (2004)... 

T. Yamasaki, P. Schlossmacher, K. Ehrlich, Y. Ogino, Formation of amorphous electrodeposited Ni-W alloys and their nanocrystallization. Nanostract. Mater. 10(3), 375-388 (1998)... 

Deposition of alloys is usually conducted in the presence of one or more complexing agents. For example, in plating of a Ni-W alloy, citrate (and sometimes also ammonia) is added to the solution. Now citrate forms two different complexes with Ni, and NH3 could form as many as five different complexes of the type [Ni(NH3) ]. In addition, the WOj" and the Ni ions can form two types of complexes with citrate. Adding the hydrogen evolution reaction this could add up to as many as ten cathodic reactions taking place simultaneously in parallel ... 

Induced co-deposition is observed for deposition of metals that cannot be deposited at all from an aqueous solution, such as W, or can barely be deposited, with a low current efficiency and poor adherence of the deposit, such as Re. However, alloys of W with the iron-group metals can readily be formed, using, for example, a solution of NiS04 and Na2W04, with citric acid added as a complexing agent. In this particular case it was shown that a Ni-W alloy is deposited from a complex containing both metals, while Ni is also deposited in parallel reactions from its complex with citrate. Very similar behavior is observed for deposition of alloys of molybdenum. 

Figure 9.3. Computer simulation of dendrites growing into a Ni Cu alloy with 41 at.% ofCii. The tints show local composition (courtesy W.J. Boettinger and J.A. Warren).

Y.Zheng, W.M.Stobbs, The tweed microstructure in B2 Ni-rich Ni-Al alloys, in Electron Microscopy and Analysis 95, ed. D.Chems, Inst Phys.Conf Ser. No 147, Inst.of Physics (1995), p.353... 

Nickel Alloys Alloy C-4 (16 Cr, 16 Mo, Balance Ni) and alloy C-276 (16 Cr, 16 Mo, 3.5 W, 5 Fe, balance Ni) have been used for closure seals on cryogenic gas cylinders because the alloys retain all their ductility down to -327°C (—557°F). The impact strength at liquid nitrogen temperatures is the same as that at room temperature. 

Similar complex data has been reported by Haowen et al. [109] for Ni-Sn-P films, again using citrate as a complexant, and by Aoki and Takano [110] for the influence of citrate concentration on the composition W in Ni-W-P alloys. In a study of the deposition of films containing up to 30 at% Sn, Osaka and coworkers [111] observed simpler behavior, evidently due to the more selective complexation of Ni2+ by citrate as a function of citrate concentration, they reported a rapid decrease in alloy deposition rate, an increase in Sn content in the deposit, and a slow decline in P content of the deposits. 

To a stirred solution of 45g 3,5-dimethoxybenzoyl chloride and 17.4g thiophen in 300 ml benzene at 0° C, add dropwise 10.5g freshly distilled stannic chloride. Stir one hour at room temperature and add 200 ml 3% aqueous HC1. Separate the benzene layer and wash the aqueous layer with benzene. Dry and evaporate in vacuum the combined benzene layers and distill the red residue (250° C bath/4.5) to get 45g 2-(3,5-dimethoxybenzoyl) thiophen(I). Recrystallize from petroleum ether. Add a solution of 21 g AICI3 in 160 ml ether to a stirred suspension of 6.1 g lithium aluminum hydride in 140 ml ether. After 5 minutes add a solution of 39g(I) in 300 ml ether at a rate giving a gentle reflux. Reflux and stir 1 hour cool in an ice bath and treat dropwise with 50 ml water, then 50 ml 6N aqueous sulfuric acid. Separate the layers, extract the aqueous layer with 3X100 ml ether and dry, evaporate in vacuum the combined ether layers. Can distill the residue (230° C bath/5mm) to get 27g oily 2-(3,5-dimethoxybenzyl) thiophen (II). Recrystallize from petroleum ether. Reflux a solution of 5g (II) in 700 ml ethanol with W-7 Raney Nickel prepared from Ni-Al alloy (see Org. Synthesis Coll. Vol 111,176(1955)) for 6 hours. Filter, evaporate in vacuum and can distill (140/0.01) to get about 2.2g oily olivetol dimethyl ether which can be reduced to olivetol as described elsewhere here. -... 

Electrodeposition of Zn-Co alloys on Ni, W, and GC electrodes from 40 to 60 mol % ZnCl2-EMIC melt containing Co(II) was investigated [182]. X-ray measurements indicated that Zn-Co alloy deposits with low zinc content are amorphous and the crystalKne nature of Zn-Co alloys... 

Hunig base W,W-dimethyl-l -naphthalenamine polymeric Hunig base diisopropyl- Raney Ni Ni-Al alloy treated with aq. NaOH (reductant, hydrogenation catalyst)... 

Another way of production is the coating of c-BN by electro-less plating with Ni-P, Ni-B, Ni-Fe-P, Ni-Cr-P, Ni-Cu-P, or Ni-W-P alloys, and mixing these powders with >1% of various carbides, borides, nitrides, silicides, and/or oxides. These powders are compacted and pre-sintered at 700-900 °C. Finally, hot-isostatic pressing at 1000-1400 °C and 1000-2000 bar is performed to reduce porosity [264]. 

A diverse composition space of ternary transition metal-Pt alloys was chosen as the starting point for the combinatorial investigation. Four transition metals, W, Co, Ni, and Ru, were selected to be base metal components of Pt-based metal alloys [18, 19]. The ternary permutation of these metals results in a total of six Pt-based ternary alloys, namely Pt-Ru-W, Pt-Ru-Co, Pt-Ru-Ni, Pt-Co-Ni, Pt-Co-W and Pt-Ni-W. Each ternary system was sampled broadly six stoichiometries were chosen ... 

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