On the role of mass-transport in electrodeposition of nickel-iron alloys
Despite the extensive use of nickel-iron, the mechanism of codeposition is not well understood. The interactions occurring during codeposition are such that nickel deposition is inhibited in the presence of iron, and the resulting alloy deposit has a much higher iron to nickel ratio than the electrolyte. This type of interactive deposition is an example of what has been termed anomalous codeposition, which is also used in describing electrodeposition of iron group elements (iron, cobalt, and nickel) with each other, or with zinc, tin, lead, and cadmium. In Chapter 2 of this thesis, a critical review of the literature is presented. Various interpretations and proposed mechanisms for the anomalous deposition of the iron-group alloys, particularly nickel-iron, is discussed. The major objectives of this review are to provide unambiguous definitions for various codeposition schemes, including the anomalous deposition itself, reflect on some of the more widely accepted hypothesis describing this phenomenon, and summarize the more recent results of other investigators in the field. To elucidate the electrodeposition mechanism of magnetic alloys, a mathematical model is developed in Chapter 3. The model is applied to a rotating disk electrode system, with well understood hydrodynamics, and incorporates homogeneous reactions of metal-hydroxide complexes. In Chapter 4, the model is further used to investigate the effect of buffering agents which are commonly used in electroplating baths. Our understanding of the mechanism of electrode processes depends on the accurate measurement of these concentrations. The interfacial value of pH is particularly important for electrodeposition of the iron-group alloys. In Chapters 5 and 6, an in-situ nonintrusive technique for surface pH measurement is investigated by theoretical and experimental methods.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6261428
- Report Number(s):
- LBL-29840; ON: DE91009090
- Resource Relation:
- Other Information: Thesis (Ph.D.). Thesis submitted by S. Hessami
- Country of Publication:
- United States
- Language:
- English
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