Tribochemical polishing of ceramics and metals

Details Tribochemical polishing of ceramics and metals Tribochemical polishing of ceramics and metals

1998-12-14

2001-05-29

Alanko, Anita (Department: 1746)

Etching a substrate: processes

Nongaseous phase etching of substrate

Using film of etchant between a stationary surface and a...

C216S018000, C216S019000, C216S038000, C216S099000, C216S100000, C216S108000, C438S691000, C438S692000, C438S747000, C438S754000, C438S756000, C438S757000

Reexamination Certificate

active

06238590

ABSTRACT:

FIELD OF INVENTION
The present invention relates to a tribochemical process for the polishing of selected ceramics or metals. This method is an improvement on traditional processes of polishing these materials such as abrasive polishing, lapping, chemomechanical polishing or mechanochemical polishing.
BACKGROUND OF THE INVENTION
Tribochemistry is a branch of chemistry dealing with chemical and physicochemical changes of matter due to the influence of mechanical energy. The technological significance of tribochemistry applies to a number of different areas including formulation of lubricant additives, fretting wear of bolted junctions, mild wear of metals, the mechanical activation of reactions in processing industries, and the operation of seals in rotating machinery to technical leads for the possible development of novel lubricants. T. E. Fischer,
Ann. Rev. Mater. Sci.
1988, 18, 303-323.
Tribochemistry has also been used in the production of an oxidized surface on ceramic or metal-ceramic materials. U.S. Pat. No. 5,073,461 (DeKoven et al.) describes a tribochemical process wherein a ceramic or ceramic-metal surface is oxidized by compressing it against an articulating ceramic or ceramic-metal surface with a sliding or rolling movement of one surface against the other under high vacuum. Oxygen or air, in an amount less than atmospheric pressure, is then introduced into the vacuum chamber while continuing the compressing of the surfaces by sliding or rolling of one surface against another.
Tribochemistry has also been used in conjunction with mechanical means for polishing of solid materials. For example, U.S. Pat. No. 4,994,139 (Biermann et al.) discloses a method of manufacturing a light-conducting device in which a layer of light conducting material is applied to a plane surface of a disc-shaped carrier body to form a light conductor body. In this process, mechanical grinding is used on the light conductor body to bring it to a thickness that exceeds the desired ultimate layer thickness by at least 50 micro-meters. The light conductor body is then subjected to alternative tribochemical and mechanical polishing until a thickness is obtained which exceeds the desired ultimate layer thickness of 10 micrometers. The light conductor body is then polished by a final tribochemical polishing until the desired layer thickness is obtained. Tribochemical polishing is carried out using SiO
2
grains having an average grain size of 30 nm in a NaOH solution having a pH value between 10 and 11.
U.S. Pat. No. 5,028,558 and U.S. Pat. No 5,284,803 (Haisma et al.) disclose similar methods for manufacturing semiconductors wherein the semiconductor body is mechanically ground to a first desired thickness, then alternately polished tribochemically and mechanically to a second desired thickness and finally polished tribochemically to the ultimately desired thickness . Tribochemical polishing is again carried out using SiO
2
grains having an average grain size of 30 nm in a NaOH or KOH solution having a pH value between 10 and 11.
It has now been found that tribochemical polishing can be used to smooth the surfaces of selected ceramics and metals without the use of abrasives such as SiO
2
.


REFERENCES:
patent: 3351555 (1967-11-01), Byers et al.
patent: 3549439 (1970-12-01), Kaveggia et al.
patent: 4994139 (1991-02-01), Biermann et al.
patent: 5028558 (1991-07-01), Haisma et al.
patent: 5073461 (1991-12-01), DeKoven et al.
patent: 5284803 (1994-02-01), Haisma et al.
patent: 5441442 (1995-08-01), Haisma et al.
patent: 5817245 (1998-10-01), Iwamoto et al.
patent: 4-336949 (1992-11-01), None
T. E. Fischer, “Tribochemistry”, Ann. Rev. Mater. Sci. 1988, 18, 303-323.

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