Study On The Mechanism, Process And Application Of Porous Nickel Prepared By Jet Electrodeposition

Porous metal material is a new type of functional and structural material with good performance; it has prospective application in a wide range and has been a heated research area of functional material all over the world. Meanwhile, the performance and characteristics of the porous metal material are directly related to its structure; variations in the porosity, features and sizes of the pores can directly influence the performance of the material.With the background mentioned above, this paper presents researches and discussions over the following aspects: aiming at the complicated processes and high costs that generally exist in the traditional porous metal preparation techniques, a whole new porous metal preparation technique-layer scanning jet electrodeposition of "sandwich-structured" porous nickel metal-is introduced. This bulk "sandwich structure" of the nickel metal has porous dendritic crystalline deposited layers as core layers, and normal thin deposited layers as the surface panels on both sides.This technique aims at the optimal design and the application of pore structure in the nickel metal, and through the manipulation of different kinds of machining parameters and control conditions, the working condition of the electrodeposition is able to shift between dendritic crystalline layer electrodepositing and normal layer electrodepositing alternately, and growth condition of the porous dendritic crystalline layers can be fairly controlled; this technique can also regulate pore structure and porosity of the core layer, growth location of normal deposited layer, and make variations to features and sizes of sandwich-like pores in the porous metal.Compared to other methods, the foam structures generated by jet electrodeposition technique totally grow up from the origin structure position. During the machining procedure, no subsidiary materials are added in, which allows a simpler process and a relatively lower cost. This technique is achieved under normal temperature and normal pressure condition, and requires not much of the environment or the equipment. This research has important and realistic significance on enriching applicable preparation processes of foam metals. Following works have been done and included in this paper:1. Researches on electrochemical mechanism and behavior of jet electrodeposition of porous metal preparation, which include: its kinetic process and polarization characteristics on cathode, the type of cathodic polarization during the process, the AC impedance behavior of the jet electrodeposition, and the electrical crystallization behavior of the jet electrodeposition of nickel.2. Theoretical analysis is conducted on the jet velocity field and pressure field of the jet electrodeposition procedure, then a fundamental mathematical model for the single-strand turbulent flow is set up. We apply the diffusion-limited aggregation (DLA) model to simulate the feature and growth process of the dendritic structures that exist during the electrodeposition procedure, and made verifying tests.3. Develop a test system for the preparation of bulk porous nickel metal processed by layer scanning jet electrodeposition. Use this system to make some bulk porous nickel samples with certain shapes and thicknesses, and study the surface features, pores, micro structures and mechanical properties.4. Porous nickel metal prepared by jet electrodeposition is treated as the current collector. Then make the electrochemical capacitor electrodes using electrode active nano-NiO material, and finally characterize the capacitor properties. Tests made indicate: Capacitors using the jet electrodeposited porous nickel metal as current collectors show typical characteristics of super capacitor, and they exist mostly in the form of faradic pseudocapacitance. With Specific capacitance of single electrode of the specimen varies within 582-527F/g. Capacitors have the advantages of low particle transfer impedance, good electrochemical capacitor performance.