Electrolysis: processes – compositions used therein – and methods – Electrolytic synthesis – Preparing inorganic compound
Reexamination Certificate
1999-08-11
2001-01-30
Gorgos, Kathryn (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Electrolytic synthesis
Preparing inorganic compound
C205S761000, C205S548000, C204S554000
Reexamination Certificate
active
06179987
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the production of metal oxides, and, more particularly, to a method and apparatus for producing magnetite particles by an electrocoagulation process.
2. Description of the Related Art
Magnetite (Fe
3
O
4
), an iron oxide, has natural magnetic properties that provide a multitude of uses in industry. For example, magnetite is widely used in the manufacturing of recording materials, printing, xerographic imaging, wastewater treatment, among having various other uses.
The quality of magnetite used has been particularly important to the magnetic recording industry. With the demand for smaller and lighter-weight magnetic recording devices, there has been an increasing need for recording mediums, such as magnetic recording tape and magnetic disks, for example, to have a higher recording density, sensitivity, and output characteristics. In order to meet these demands, the magnetite particles produced would desirably have a smaller particle size with a higher coercive force.
Magnetite has been shown to form as an intermediate during the oxidation of iron. Initially, a layer of ferric oxide is formed, the underlying layer of iron then reacts with the ferric oxide to reduce it and form zones of magnetite and ferrous oxide. Currently, chemical processes are employed to produce magnetite. In accordance with one of these processes, magnetite is produced by a high temperature hydrogen reduction of ferric oxide precipitated from a solution, which forms magnetic particles by electrodeposition. In this process, iron and other ions are present in the solution, and the metal is deposited using a pulsating electric field. The deposited metal is then sloughed off using a pulsating sonic field. In accordance with another chemical process, the production of ferromagnetic materials by electrochemical galvanic coagulation in an aqueous medium is performed. This chemical process is fully described in U.S. Pat. No. 5,658,450.
Although these chemical processes are known to produce magnetite, such processes typically produce relatively large-sized particles having a low coercive force. In addition, the aforementioned chemical processes also tend to produce the magnetite with a relatively high impurity content. Accordingly, the optimal characteristics of magnetic recording materials are not fully realized as a result of these undesirable characteristics encountered by these current practices.
SUMMARY OF THE INVENTION
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above by providing a method and apparatus for obtaining nano-sized metal oxide particles.
Accordingly, the present invention provides for the production of metal oxide particles, and is particularly advantageous in producing magnetite particles. The present invention includes a method for submerging a pair of metal electrodes in an electrolytic solution, and applying a voltage to the pair of electrodes for a period of time sufficient to produce the metal oxide particles.
In one aspect of the present invention, an apparatus is provided for producing a metal oxide, such as magnetite particles. The apparatus comprises a container adapted to hold an electrolytic solution, and a pair of metal electrodes submerged in the electrolytic solution of the container. A power supply is further provided to apply a voltage to the pair of electrodes for a period of time sufficient to produce the metal oxide particles. The metal electrodes used to produce magnetite are preferably constructed of iron in the form of carbon steel plates. The electrodes may be constructed of other types of transitional metals including, but not necessarily limited to, cobalt, nickel, cadmium, zinc, manganese, or magnesium. The electrolytic solution typically includes aqueous sodium chloride to provide sufficient conductivity between the electrodes.
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DePaoli David W.
Shor Joel T.
Tsouris Constantinos
Gorgos Kathryn
Keehan Christopher M
U-T Battelle, LLC
Williams Morgan & Amerson
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