RUI: Anomalous Codeposition of Nickel-Iron and Nickel-Zinc Alloys

点击翻译按钮获取中文摘要

9404871 Harris This research is an experimental examination of anomalous codeposition in two different systems, nickel-iron and nickel-zinc. There are several reasons for choosing these particular systems: 1) to determine the mechanism of anomalous deposition; 2) the systems have nickel in common, but the alloys produced when nickel is combined with iron and zinc have different properties; 3) both systems are of importance commercially. Experiments critically test the models or theories of anomalous codeposition. The project starts with the production of alloy deposits within a test matrix that includes the following variables: less noble metal concentration in the solution, pH, current density, and temperature. The deposits produced in these experiments are characterized with respect to their composition, morphology, microstructure and crystalline phase content. These tests identify conditions under which anomalous codeposition does not occur, as well as regimes of anomalous codeposition that are sufficiently dissimilar to suggest different mechanisms. Two additional issues will be examined later in the project. First, hypophosphite, which is able to eliminate anomalous codeposition (at least in the nickel-iron system), will be used as a probe for testing the various anomalous codeposition mechanisms. Secondly, the role of hydrogen, which has been discounted in the nickel-iron system but cannot be ignored with nickel-zinc, will be examined using the electrochemical hydrogen permeation technique. %%% This work should assist in the further refinement of the commercial production and utilization of electrodeposited alloys. Permalloy electrodeposition technology has played an integral role in the evolution of the hard disk drive, and further improvements are limited by our present understanding of the electrochemical processing of this materials. Also, a better understanding of the nickel-zinc system should enhance its utilization as a corrosion- re sistant coating for steel sheet used in automobiles and other applications. ***