Electrolysis: processes – compositions used therein – and methods – Electrolytic coating – Involving measuring – analyzing – or testing
Reexamination Certificate
1999-03-30
2001-03-13
Gorgos, Kathryn (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Electrolytic coating
Involving measuring, analyzing, or testing
C204S22400M, C204S228700, C205S084000, C205S104000, C205S109000, C205S258000
Reexamination Certificate
active
06200450
ABSTRACT:
BACKGROUND
1. Technical Field
The present disclosure relates to Ni-Fe-W-P alloys and a method and apparatus for depositing same.
2. Background of Related Art
Chromium plating offers unique deposit properties, including brightness, discoloration stability at atmospheric conditions and long preservation of the luster. But uniformity of the deposits is poor, the required current density is high, current efficiency is low, and the cost of energy is great. At the same time, chromium ions are very poisonous. Any chromium mist that escapes or direct drainage of waste water containing chromium ions can greatly contaminate atmosphere and water sources, adversely affecting the health of humans.
It would be desirable to provide the beautiful color and luster, good corrosion resistance and excellent wear resistance such as those of chromium deposits without the aforementioned shortcomings. Many substitutes for chromium deposits have been investigated and developed, of which, up to now, Sn-Co alloy seemed to be the most promising. See, U.S. Pat. Nos. 3,966,564 and 3,951,760, the disclosures of which are incorporated herein by reference.
Compared with chromium plating deposits, Sn-Co alloy deposits have the following advantages:
1. Sn-Co alloy deposits have the same excellent luster and beautiful color as chromium deposits and can be used as decorative deposits.
2. Corrosion resistance of Sn-Co alloy deposits is superior to that of chromium deposits and can be used as advanced protection deposits.
3. Sn-Co alloy deposits have good adhesion, excellent toughness, low internal stress, no porosity and no cracks.
4. Dispersing and penetrating abilities are very good. Throwing and covering power are very good.
5. Current efficiency of Sn-Co alloy plating is one to four times higher than that of chromium plating.
6. Because Sn-Co alloy plating is not poisonous, draining waste gas and water can be easily handled.
But the hardness of Sn-Co alloy deposits is about HV 500-600 and wear resistance is only one half that of chromium plating deposits.
In order to overcome the disadvantages of Sn-Co alloy various alloy plating deposits have been developed as substitutes. For example, U.S. Pat. No. 4,529,668 discloses a W-Co-B electrodeposition alloy.
U.S. Pat. No. 5,614,003 discloses electroless deposition of Ni-Mo-P, Ni-Cu-P, Ni-Sn-P, Co-W-P and Ni-W-P combinations. These coatings have high hardness, good wear resistance and good corrosion resistance, but suffer from such problems as low current efficiency and high energy cost. For example, the electrodeposition rate of W-Co-B is only about 1.6 &mgr;m-50 &mgr;m per six hours at a solution temperature of 72-86° C.
In order to overcome these disadvantages of prior known deposition compositions and methods the present method has been developed.
SUMMARY OF THE INVENTION
In one aspect, a method is provided herein for electrodepositing a metallic coating onto a surface of an object. The method comprises the steps of: preparing an electrodeposition fluid which contains in solution, based on the total metal content of the solution, from about 65 percent to about 70 percent nickel, about 10 percent to about 30 percent by weight of iron, about 5 percent to about 10 percent by weight of tungsten, and about 1 percent to about 3 percent phosphorous; mounting the object on a support; providing an anode which is movable over the object, the anode having an applicator in contact with a first portion of the surface of the object, a second portion of the surface of the object not being in contact with the applicator; supplying the electrodeposition fluid to the applicator; and supplying electric current to the anode and to the object to deposit an alloy containing nickel, iron, tungsten and phosphorous onto the object.
The method advantageously provides for the deposition of a Ni-Fe-W-P alloy having good corrosion and wear resistance with high current efficiency and low energy cost.
Also provided herein is an apparatus for electrodepositing a metallic coating from a working solution onto a surface of an object, comprising: a support for mounting the object, the support being rotatable around a horizontal axis; an anode; transport means for reciprocatingly moving the anode in a horizontal direction parallel to the axis of the support; an applicator attached to the anode for contacting a selected portion of the surface of the object; a fluid supply communicating with the applicator for supplying working solution to the selected portion of the surface of the object; a power supply connected to the anode for creating an electrical potential between the object and the anode; and a microprocessor containing logic therein for effectuating correction of geometric error in surface topography of a platable object, the microprocessor being operatively connected to the power supply.
Additionally, a method is provided herein for leveling the surface of a platable object comprising: providing a platable object operatively mounted to an electrodeposition apparatus, the platable object having a surface containing a geometric error in its surface topography; providing a sensor for determining the surface topography of the object and generating a first signal corresponding to the surface topography; sending the first signal to a microprocessor which compares the geometric error to a value corresponding to a desired surface topography of the object; calculating the magnitude of the geometric error from the difference between the actual surface topography and the desired surface topography of the object; generating a corrective signal corresponding to the magnitude of the geometric error; and sending the corrective signal to an electric current source thereby causing the electrodeposition apparatus to deposit onto the surface of the object a quantity of leveling agent sufficient to at least partially correct the geometric error of the platable object.
Also provided herein is an electrodeposition fluid which contains in solution, based on the total metal content of the solution, from about 5 percent to about 15 percent iron, about 75 percent to about 90 percent nickel, about 3 percent to about 15 percent tungsten and about 0.5 percent to about 4.0 percent phosphorous, and a reducing agent.
REFERENCES:
patent: 4287043 (1981-09-01), Eckert et al.
patent: 4786376 (1988-11-01), Vaaler
patent: 5433797 (1995-07-01), Erb et al.
patent: 5614003 (1997-03-01), Mallory
Dilworth & Barrese LLP
Gorgos Kathryn
Leader William T.
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