The Mechanism of the Tungsten Alloy Plating Process

Clark, W.E.; Lietzke, M. H.

doi:10.1149/1.2779712

Cited by 46 publications

(27 citation statements)

References 11 publications

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“…There is no final agreement as to the mechanism by which the deposition of reluctant metals occurs, and the catalytic hypothesis is merely a restatement of the phenomenon with the unknown factors termed catalytic (32,33). Furthermore, the existence of an adsorbed layer, which was deduced here, is in accordance with considerations described elsewhere (29,31,(35)(36)(37). the explanation given here supports the concepts of catalytic action of freshly deposited iron group metals.…”

Section: Discussionsupporting

confidence: 89%

Structure of Noncrystalline Co-25 a/o W Electrodeposit

Omi¹,

Yamamoto²,

Glass

1972

J. Electrochem. Soc.

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Noncrystalline electrodeposits of Co-25 atomic per cent (a/o) W prepared from ammoniacal alkaline tartrate electrolyte were studied by x-ray diffraction. A model for the structure of this alloy was developed. The principal assumptions involved in constructing the model are based mainly on requirements for the electrodeposition. The model requires that the alloy consist of distinct basic structural units in the form of tetrahedra, each composed of three cobalt atoms and one tungsten atom. The dimensions of this structural unit correspond to those of the intermetallic compound Co3W. Certain criteria .govern the bonding of the tetrahedra to form larger aggregates. The scattermg function calculated from the model agrees quite well with the diffraction data. The model also accounts for differences in the composition of amorphous deposits prepared at different current densities. The electrochemical requirements for the formation of this structure by electrodeposition are discussed. The operation of similar processes in the electro-or chemical deposition of other alloys having stoichiometric composition is considered. * Electrochemical Society Active Member. ABSTRACTThe variables affecting the uniformity of sheet resistance for a two-step shallow phosphorus emitter diffusion were examined. The source used was POCla. The uniformity of sheet resistance (and hence surface concentration) was predominantly dependent on the variables during the deposition process.

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Section: Discussionsupporting

confidence: 89%

Structure of Noncrystalline Co-25 a/o W Electrodeposit

Omi¹,

Yamamoto²,

Glass

1972

J. Electrochem. Soc.

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“…The potential required for the deposition of the tungsten alloys is more noble than the potential required for the deposition of the metal (Fe, Ni, or Co) by itself (8)(9)(10). According to data published by Markwell and Holt (11), a criterion for tungsten deposition is that the dynamic cathode potentials of the codepositing ion (Ni, Co, Fe) solutions, with and without tungsten ion, must be within 85 mv of each other.…”

Section: Resultsmentioning

confidence: 99%

Effect of Addition Agents on Tungsten Codeposition

Sallo

Fisher²

1960

J. Electrochem. Soc.

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Small quantities of certain addition agents will prevent the codeposition of tungsten with iron, nickel, or cobalt. Data are presented comparing addition agent concentration with the amount of tungsten in a nickel-tungsten codeposit. Polarographic data indicate that addition agents which prevent tungsten codeposition are capable of being adsorbed at a Hg cathode and form complexes with the codepositing metal ion. These complexes are more readily reduced than is the original codepositing species. The cathode potential of the deposition process is lowered to a more positive potential by the addition agent. Structural studies show that the deposit does not consist of alternate layers of tungsten and codeposited metal as is required by the catalytic reduction mechanism. It is shown that the addition agent effect can be explained by a mechanism of codeposition involving complex formation.Many claims have been made for the deposition of pure tungsten from aqueous tungstate solution (1-3). Subsequent investigation of these processes has shown that the deposits always contain iron, nickel, or cobalt (codepositing metal ion) (4), and that deposition ceases when these impurities are exhausted from the plating solution. When no such impurities are present in the plating solution, oxides of tungsten may be deposited at the cathode; however, under these conditions reduction of tungstate to tungsten has not been observed.Many baths have been developed for the codeposition of tungsten with iron, nickel, or cobalt. The most successful of these are the complex ammoniacal baths which have been developed by Brenner (5) and by Holt (6). Brenner's baths allow the codeposition of sound Ni-W deposits containing 20% tungsten. Iron-tungsten deposits containing 50% tungsten can be plated from such baths. Two mechanisms have been proposed to explain the codeposition process. These are the catalytic reduction mechanism and the complex formation mechanism.The catalytic reduction mechanism proposes that laminations observed in the codeposits are alternate layers of tungsten and the codeposited metal (iron, nickel, or cobalt) (7). The codeposited metal acts as a catalytic surface on which, in the presence of hydrogen, the tungstate anion is reduced chemically and electrochemically to metallic tungsten. When a layer of tungsten has covered this catalytic surface, the deposition ceases and the formation of a fresh layer of catalytic codeposited metal begins.The complex formation mechanism describes the codeposition as taking place from some complex of tungstate and the codepositing metal ion (7). The function of the codepositing metal ion is to provide a reducible tungstate complex. The major disadvantage of the complex formation mechanism is that no complex of tungstate with ions of iron, nickel, or cobalt has been observed.The effect of addition agents on tungsten codepo-1 Present address: Minneapolis-Honeywell Regulator Company, Research Center, Hopkins, Minnesota.sition and data indicating that the codeposits are solid solutions are discusse...

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“…In the absence of the iron group metal ions, these elemental metals have not been electrodeposited from an aqueous media. However, complexation of the IG metal ions and V, RE, Mo, W can lead to co-deposition of the alloys (16)(17)(18)(19). Muller showed that metallic Cr can be electrodeposited directly from chromic acid (20).…”

Section: Electrodeposition Mechanismmentioning

confidence: 99%

Aqueous Electrodeposition and Mechanism of Iron Group-Vanadium Ternary Alloys

2011

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Composition of ternary CoFeV deposits can be varied and tailored by control of the [Fe]/[Fe + Co] solution molar ratios and solution pH. Near 2V Permendur compositions were obtained with B s of 2.35T and B s of 2.39T for direct current (DC) and pulse current (PC) deposits, respectively. Annealing deposits in vacuum at 820 o C for 2 hours increased B r to equivalent 2V Permendur. X-ray diffraction patterns show microstructures of mixed HCP, FCC and BCC planes, depending on deposit composition. Co-rich deposits had HCP preferred orientation but as Fe content increases HCP plane disappeared and Fe BCC plane became the preferred orientation. Surface morphology changed from a needle-like structure in Co-rich deposits to nodular appearance with increasing Fe content. A hydrogen atom mechanism for the reduction of the oxovanadium, Co(II) and Fe(II) within the heterodinuclear and heterotrinuclear biscitrate complexes is proposed. This mechanism is also applicable to aqueous electrodeposition of IG-Mo and IG-W alloys.

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The Mechanism of the Tungsten Alloy Plating Process

Cited by 46 publications

References 11 publications

Structure of Noncrystalline Co-25 a/o W Electrodeposit

Structure of Noncrystalline Co-25 a/o W Electrodeposit

Effect of Addition Agents on Tungsten Codeposition

Aqueous Electrodeposition and Mechanism of Iron Group-Vanadium Ternary Alloys

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