U.S. patent number 3,776,762 [Application Number 05/190,098] was granted by the patent office on 1973-12-04 for dry lubrication.
This patent grant is currently assigned to Du-Kote Corporation. Invention is credited to John Bernath.
United States Patent |
3,776,762 |
Bernath |
December 4, 1973 |
DRY LUBRICATION
Abstract
Applying a dry, lubricous, protective coating of polymerous
material on the surfaces of parts in a thickness of about 100 A.
and in added increments thereof by cleaning the surfaces of the
parts by subjecting the parts to ionic glow discharge in a low
vacuum atmosphere and then coating the cleaned surfaces of the
parts with polymerous material by subjecting the parts to ionic
bombardment in an ionized atmosphere of fluorcarbon gas at about 6
.times. 10.sup.-.sup.6 Torr. This invention has to with the
establishment and application of protective and lubricous coatings
to parts surfaces and is more particularly concerned with a novel
process for applying a thin durable coating of polymerous, organic
material to parts surfaces. Throughout the many arts there is an
ever-increasing requirement and need to protect items or parts
against wear and/or the deleterious effects of their environments;
which requirement and/or use would be best served by a thin coating
of polymerous material. While thin coatings of metallic materials,
such as chromium and copper can be established on parts surfaces by
electro plating and vapor deposition processes and while thin
mineral oxide coatings can be established on parts surfaces by
anodizing processes and the like, the prior art has failed to
develop and provide a suitable means or process whereby organic,
polymerous materials can be lightly or thinly applied to parts
surfaces. In regards to the above, the term "thin"as here used
refers to coatings the thickness of which is from .000001 inches to
.000010 inches and such that measurement thereof is most often
effected by optical means and translated in terms of Angstroms. It
is an object of my invention to provide a novel process which is
effective to apply strong, integrated, durable coatings of
polymerous material to parts surfaces in uniform thickness of about
100A. It is another object and feature of my invention to provide a
novel process of applying coatings of polymerous material to parts
surfaces which coatings are sufficiently thin that they are
visually undetectable upon ordinary or normal visual examination
and such that parts surfaces can be advantageously coated and
protected without affecting their aesthetics. It is yet another
object and feature of my invention to provide a process of the
character referred to which enables and makes possible the
application of dry, lubricous coatings on bearing surfaces of
parts, which coatings are sufficiently thin that normal,
established, mechanical working tolerance between related, coated,
parts is not adversely affected. Still further, it is an object and
feature of my invention to provide a process of the character
referred to whereby protective, dry, lubricous coatings of
dielectric polymerous material can be advantageously applied to the
surfaces of magnetic and/or electrical components in a sufficiently
thin state that they do not electrically insulate or otherwise
adversely affect the magnetic and/or electrical characteristics and
functions of the components. It is an object and a feature of the
present invention to provide a process of the character referred to
which is such that an applied coating of polymerous material on the
surfaces of a part conforms to the surfaces of the part and does
not migrate and/or flow in such a manner as to fillet corners, peel
or otherwise result in undesirable variations in density and/or
thickness of the coating. Still further, it is an object of the
present invention to provide a process of the character referred to
above which is such that a dry, lubricous, protective, polymerous
coating can be advantageously applied to metallic or non-metallic,
porous and non-porous surfaces.
Inventors: |
Bernath; John (Los Angeles,
CA) |
Assignee: |
Du-Kote Corporation (Los
Angeles, CA)
|
Family
ID: |
22700009 |
Appl.
No.: |
05/190,098 |
Filed: |
October 18, 1971 |
Current U.S.
Class: |
427/490;
427/255.6; 427/294; 427/534 |
Current CPC
Class: |
B08B
7/0035 (20130101); B05D 1/62 (20130101); B05D
3/144 (20130101) |
Current International
Class: |
B05D
3/14 (20060101); B05D 7/24 (20060101); B08B
7/00 (20060101); B44d 001/18 (); C08f 003/22 () |
Field of
Search: |
;117/93.1GD,16R,161UF |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Martin; William D.
Assistant Examiner: Newsome; John H.
Claims
Having described my invention, I claim:
1. The method of depositing an electrically non-insulating, dry,
lubricating, protective film of fluor-carbon polymer having a
thickness not more than 200 Angstroms in thickness onto a surface
of an article which comprises placing the article into a vacuum
chamber and connecting the article to a power supply as an anode
with the entire surface to be coated exposed, introducing an amount
of fluorocarbon gas substantially equal to the amount of polymer in
the finished coating, establishing a glow discharge in the chamber
between the article and a cathode and exhaustively depositing the
fluorocarbon gas onto the surface of the article thereby
extinguishing the glow.
2. The method set forth in claim 1 which includes establishing a
glow discharge in the chamber between the article and cathode
before introducing the gas to clean the surface of the article.
3. The method set forth in claim 1 wherein the atmosphere in the
chamber is established at 6 .times. 10.sup..sup.-6 Torr prior to
introduction of the gas.
4. The method set forth in claim 1 which includes establishing a
glow discharge in the chamber between the article and cathode
before introducing the gas to clean the surface of the article and
wherein the atmosphere in the chamber is established at 6 .times.
10.sup..sup.-6 Torr prior to introduction of the gas.
5. The method of depositing an electrically non-insulating, dry,
lubricating, protective film of fluor-carbon polymer having a
thickness not more than 200 A. in thickness onto a surface of a
nonconductive article, which comprises placing the article on an
anode support connected with a power supply and within a vacuum
chamber and with the surfaces of the article to be coated exposed,
introducing an amount of fluorcarbon gas substantially equal to the
amount of polymer in the finished coating and which coats the
anode, establishing a glow discharge in the chamber between the
anode and a cathode and exhaustively depositing the fluorocarbon
gas onto the surface of the article and the anode thereby
extinguishing the glow.
6. The method set forth in claim 5 which includes establishing a
glow discharge in the chamber between the article and cathode
before introducing the gas to clean the surface of the article.
7. The method set forth in claim 5 wherein the atmosphere in the
chamber is established at 6 .times. 10.sup..sup.-6 Torr prior to
introduction of the gas.
8. The method set forth in claim 5 which includes establishing a
glow discharge in the chamber between the article and cathode
before introducing the gas to clean the surface of the article and
wherein the atmosphere in the chamber is established at 6 .times.
10.sup..sup.-6 Torr prior to introduction of the gas.
Description
The foregoing and other objects and features of my invention will
be fully understood from the following detailed description of this
invention, throughout which description reference is made to the
FIGURE in the accompanying drawing in which an apparatus suitable
for carrying out this invention is diagrammatically
illustrated.
The apparatus shown in the FIGURE of the drawing includes a vacuum
chamber X defined by a platform P and a downwardly opening bell B
engaged on and supported by the platform. Suitable sealing means Y
are provided between the platform and the rim of the bell to seal
the chamber tightly.
Within the bell B, and projecting upwardly into the upper portion
of the chamber X is an anode structure A comprising a post-like
structure projecting upwardly from the platform P and a rack-like
carrier on the post structure and on which articles of work or
parts I, the surfaces of which are to be coated, are secured by
clips or the like.
Within the bell B, at the lower portion of the chamber, in
predetermined spaced relationship with the carrier of the anode A
is a cathode structure C. The cathode structure C is carried by the
platform P, in insulated relationship therewith and can be of any
suitable design and construction.
In addition to the above, the apparatus includes a high vacuum
system S which system includes a pump D, the inlet of which is
suitably connected with the chamber X.
In practice, the system S and the pump D thereof can be any one of
several available makes and designs of high vacuum pumping means or
systems, without departing from the spirit of the invention.
In the drawing I have shown one such high vacuum system in
diagramatic form. Since such systems are well known to those
skilled in the art, I will not burden this disclosure with further
and unnecessary detailed description of the vacuum system or its
operation.
The apparatus next includes suitable control means M for
selectively controlling and monitoring the operation of the vacuum
system S. The means M includes a switch for putting the pump D into
and out of operation, manually or electrically operated valves for
controlling the flow of air and gases moved or handled by the
system S and pressure and temperature gauges for monitoring and
indicating the pressure and the temperature within the chamber X
and of the work I and/or the anode substrate of said work. In
practice, the means M can include automatic controls and the like
which controls can be such that operation of the system S is
automatic.
Next the apparatus includes a suitable direct current power supply
E. The power supply is connected between a suitable alternating
current services W and the cathode structure C.
The power supply E is provided with controls N to accurately
control the voltage to the cathode structure. The controls for the
power supply can include timing means and servo means related to
the timing means and to the system S whereby programmed sequential
changes in applied voltage, required in carrying out my process,
can be made automatically.
Finally, the apparatus includes gas supply means G for introducing
a desired gas into the chamber X, as will hereinafter be described.
The means G, like the means M and N can include automatic controls
O, related to the means M and N to automate operation of the
apparatus.
Since in practice the exact nature and form of the several control
means referred to above can vary widely without departing from the
spirit of this invention, detailed illustration and description of
such means would only serve to unduly burden this disclosure and
will therefore be dispensed with.
In the case illustrated, the platform P is established by the top
of a cabinet. The system S, power supply E, means G and the
controls therefor are suitably related to and can be arranged
within the cabinet as indicated in the drawing.
The process that I provide includes two or three basic steps;
first, the careful and thorough cleaning of the work or part
surface to be coated; second, the application of a base coating on
the surface; and third, if desired or necessary, finishing of the
base coating.
Since the coating to be applied is extremely thin, being less in
thickness than matter left on a surface by engaging it with one
finger, that is, less in thickness than a fingerprint, it is
imperative that surface to be coated be absolutely clean or free of
all foreign matter so as to avoid or eliminate degradation of
adhesion of the polymerous coating material to or with the
surface.
In carrying out my new process, the surface of a work part I to be
coated is first cleaned by glow discharge within the chamber X of
the apparatus employed.
To effect glow discharge cleaning of the work part surface, the
part is suitably secured to or connected with anode structure A
within the chamber X. This is effected by raising the bell B above
the platform P to expose and make the carrier of the anode
structure accessible, securing the work part I thereto and then
lowering the bell to engage the platform and its related sealing
means Y, and to thereby reestablish the chamber X.
With the work part thus secured or connected with the anode
structure, in spaced relationship above the cathode structure C,
the vacuum system S is put into operation and the chamber is
evacuated or roughed to at least 40 microns of mercury, for
example, to 50 microns of mercury and a suitable direct current
voltage is applied to the cathode structure by means of the power
supply E.
It is determinable that the surface of the work part is
sufficiently clean when the ionic glow generated in the chamber X
by the electron flow between the cathode and anode structures
diminishes and/or is extinguished.
When the parts are thus cleaned, the power to the cathode is
terminated and operation of the vacuum system S is continued until
the atmosphere within the chamber X reaches 1 micron of mercury (or
to the limit of its roughing mode) and the part is allowed to
cool.
It is to be noted that the process of cleaning set forth above and
which constitutes the first step of my new process is an old
process of cleaning employed in the art of vapor depositing
meaterials and is commonly referred to as glow discharge
cleaning.
At this time, and in the carrying forward of my new process, a base
coating of polymerous material is applied to the part surface.
The base coating referred to above is applied by putting the high
vacuum section or mode of the vacuum system S into operation and
evacuating the chamber X further to 6 .times. 10.sup..sup.-6
Torr.
When the atmosphere to which the work part I is exposed reaches 6
.times. 10.sup..sup.-6 a suitable fluorocarbon gas is introduced
into the atmosphere in the chamber X by and from the means G.
Sufficient gas is introduced so that the desired and necessary
atmosphere or pressure is established in the chamber. For example,
an atmosphere at about 6 .times. 10.sup..sup.-3 Torr is
established.
Next, direct current is conducted to the cathode structure and a
flow of electrons from the cathode to the anode is established. The
electron flow ionizes the fluorocarbon molecules in the atmosphere.
The negative charged fluorocarbon ions drive toward and impinge
upon the surface of the work part. The ions of fluorocarbon
molecules, when impinging upon the surfaces, give up extra
electrons to become neutral and establish solid polymerous
particles, which are welded to the work part surface.
The current directed to the cathode, in establishing the base coat,
is controlled and is sufficient to establish and maintain desired
ionization of the gas in the atmosphere in the chamber X. The
magnitude of the current controls the rate at which the material is
deposited and can be visually monitored by the ionic glow generated
within the chamber. Since the rate at which the material can be
advantageously deposited varies upon the physical characteristics
of the surface substrate, temperature parameters and other like
factors, no set or fixed current can be set forth.
The current is applied and the noted ion bombardment onto the part
surface is continued until the base coating covers the surface of
the work part and further, until the temperature of the work part
or surface substrate is heated, by the heat generated in the
chamber, to a predetermined maximum allowable temperature, which
temperature may be less than 100.degree.F, or a temperature
substantially greater than that, depending upon the physical
characteristics of the substrate.
The base coating thus applied can be about 100A. in thickness but
is preferably about 200A. in thickness.
The thin base coating thus applied tends to be a thin agglomerate
affording minimal inner or self support and minimal adhesion on or
with the surface of the work part. In many instances where the
coating is for environmental protection only and is not to be
subjected to wear or the like, the base coating is adequate or
sufficient by itself.
When the coating it to be subjected to external mechanical forces
and in carrying out my process further, the base coating is filled
and welded by allowing the part to cool and by repeating the last
described step of ionizing the fluorocarbon molecules and
bombarding the previously applied base coating with the
fluorocarbon ions. The bombardment of the base coat with additional
ions of fluorocarbon compacts and fills the conglommerate base
coating and builds up the coating to a solid state where it affords
substantial or great inner support and greatly enhanced bond
strength and/or adhesion to its related surface of the work
part.
The ions of fluorocarbon impinging on the base coating compact the
material of base coating as they impinge thereon. As they impinge
on the base coating they give up their extra electrons and weld
with the base coating as they assume a solid state. They further
tend to enter and to fill any pores, interstices and the like
occurring in the base coat to establish an impervious polymerous
coating.
The second ionic bombardment noted above is continued until the
work or the substrate of the surface being coated reaches the
maximum permissible temperature, whereupon the power is turned off
and the part is permitted to cool.
By repeating the last noted finishing step of my process two or
more times, the coating can be built up, made more dense and solid
and its durability increased to substantially any desired extent
within the inherent limitations of the polymerous material.
In practice, the second and third or more finishing steps that I
provide tend to build up and increase the thickness of the coating
but not to an appreciable extent. For example, a base coat of 200
A. when subjected to three finishing ionic bombardments, each equal
in duration and intensity with the bombardment which established
the base coat, results in a finishing coat about 600 A. thick, not
a coating 800 A. thick as might be expected. The foregoing example
appears to be clear indication that subsequent ionic bombardment of
previously deposited material compacts the previously deposited
material as noted above.
Having described but one typical preferred form and carrying out of
my invention, I do not wish to be limited to the specific details
herein set forth but wish to reserve to myself any modifications or
variations which may appear to those skilled in the art and which
fall within the scope of the following claims.
* * * * *