U.S. patent number 3,754,329 [Application Number 05/184,848] was granted by the patent office on 1973-08-28 for razor blade with rf sputtered coating.
This patent grant is currently assigned to Warner-Lambert Company. Invention is credited to George C. Lane.
United States Patent |
3,754,329 |
Lane |
August 28, 1973 |
RAZOR BLADE WITH RF SPUTTERED COATING
Abstract
The specific disclosure provides for a razor blade comprising at
least one cutting edge portion defined by two face portions having
a narrow included angle therebetween. At least a portion of each of
the face portions has an RF sputtered coating of a hard metal
having a thickness of less than about 600 Angstrom units. The
disclosure also provides for coating the sputtered metal coating
with a sputtered coating of an organic plastic material having a
thickness of from about 200 to about 2000 Angstrom units.
Inventors: |
Lane; George C. (Danbury,
CT) |
Assignee: |
Warner-Lambert Company (Morris
Plains, NJ)
|
Family
ID: |
26880529 |
Appl.
No.: |
05/184,848 |
Filed: |
September 29, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
680794 |
Nov 6, 1967 |
3635811 |
|
|
|
Current U.S.
Class: |
30/346.53 |
Current CPC
Class: |
B26B
21/54 (20130101); C23C 14/34 (20130101); B05D
5/083 (20130101); H01J 37/34 (20130101); C23C
14/12 (20130101); B05D 1/62 (20130101) |
Current International
Class: |
C23C
14/12 (20060101); B26B 21/54 (20060101); C23C
14/34 (20060101); H01J 37/34 (20060101); B05D
1/00 (20060101); H01J 37/32 (20060101); B26B
21/00 (20060101); B26b 021/54 () |
Field of
Search: |
;30/346.53,346 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Simpson; Othell M.
Assistant Examiner: Smith; Gary L.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This patent application is a division of copending U. S. Pat.
application Ser. No. 680,794, filed Nov. 6, 1967, now U. S. Pat.
No. 3,635,811.
Claims
What is claimed is:
1. A razor blade including at least one cutting edge portion
defined by two face portions having a narrow included angle
therebetween, said razor blade having a radio frequency induced
plasma sputtered metal containing coating on at least a portion of
each of said face portions, said coating having a thickness of less
than about 600 Angstrom units.
2. A razor blade as defined in claim 1 in which said coating
comprises a metal alloy having a thickness of from about 100 to
about 600 Angstrom units.
3. A razor blade as defined in claim 2 in which said alloy is an
alloy of nickel, iron and chromium.
4. A razor blade as defined in claim 1 in which said coating is an
iron and carbon compound.
5. A razor blade as defined in claim 1 in which said coating
consists of chromium.
6. A razor blade as defined in claim 5 in which said thickness is
between about 100 and about 600 Angstrom units.
7. A razor blade as defined in claim 1 in which said coating is a
hard metal.
8. A razor blade as defined in claim 7 in which said thickness is
between about 100 and about 600 Angstrom units.
9. A razor blade as defined in claim 7 in which said metal is
chromium.
10. A razor blade as defined in claim 1 in which said coating is a
metallic oxide.
11. A razor blade as defined in claim 10 in which said metallic
oxide is chromium oxide.
12. A razor blade as defined in claim 7 wherein said sputtered hard
metal coating has thereon a sputtered coating of an organic plastic
material having a thickness of from about 200 to about 2000
Angstrom units.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
Generally, the present invention relates to a novel method and
apparatus for surface coating of articles. More particularly, the
field of the invention is that of metal substrate coating by a
process analogous to metal transfer by so-called cathodic
sputtering. In this process, the principal elements are an article
or substrate to be coated, a coating material, a target plate for
holding the coating material, electrode plates for causing gas
plasma articles to strike the target to release the coating
material, and means to control the deposition of the coating and
means for carrying the article to be coated and for exposing the
desired portions thereof to the sputtered coating.
The principal differences between the instant method and true
cathodic sputtering are that the sputtered material need not be
metallic, it is not a part of the cathode, and the process is of
greatly improved efficiency in regard to rate and accuracy of
deposition, operating temperature and in many other respects which
are referred to further herein.
The method of the invention is desirably carried out by placing the
electrode plates in a very high vacuum to form a "peak" or apex,
with the upper edges thereof adjacent each other, and the lower
edges more widely spaced apart and with an opening therebetween at
the lower edges, placing the target plates immediately adjacent the
inner surface of the electrode plates, impressing a very high
frequency alternating current on the plates, causing electron flow
therebetween and development of a high charge thereon, and
"leaking" argon or like gas into the inter-electrode space.
Thereupon, the electrons bombard the argon, ionizing it, and the
plasma particles thus produced are attracted to the target plates
by the space charge on the electrode plate. The plasma particles
strike the target with such momentum that atoms or molecules from
the target are "sputtered" from the target, whence, they are
attracted to the article or substrate, which is suitably biased
with regard to the electrode and target plates. Another aspect of
the invention relates to the provisions of a mechanism for holding
the desired articles or substrate, in this case, a plurality of
razor blades, so that they may be passed in a controlled manner
beneath the target plates containing the coating material. This
mechanism may be generally described as a drum which is adapted to
support a plurality of hubs which in turn support carrier means on
which razor blades are removably mounted for coating. The drum and
hubs are arranged, by means of an epicyclic gear or chain
mechanism, so that they rotate in a desired timed relation about
two axes so as to expose the desired surfaces thereof to the
opening beneath the target plates at particular angles to present
those portions of the blade it is desired to coat to the target
plates.
2. Description of the Prior Art
In general, the prior art methods of coating particular substrates
with various materials, particularly covering substrates with thin
metallic films, has been accomplished by vacuum deposition of a
thin film, generally by methods classified as evaporation,
according to the following generally known methods.
A first method was an ordinary evaporation of a metal coating from
a hot filament, wherein the filament was heated and the metal
attached thereto was merely evaporated in the vacuum away from the
filament along relatively straight lines in all directions, coating
whatever object lay in their path. For example, in the art of
electron microscopy, it is known to "shadow" a substrate by
evaporating gold or other low boiling point metal onto a specimen
in order to create solid phase or permanent "shadows" which would
be easily visible under a microscope.
An improvement in the ordinary evaporation method was the so-called
electron beam deposition whereby the coating material was held in
one location and an electron beam was directed at the coating
material, the beam being formed and maintained by the application
of a magnetic field to an electron source. A heated filament was
used in this method.
Another known method is so-called diode sputtering, wherein high
energy electrons strike and ionize atoms of an inert gas as argon,
and the ionized particles or plasma thus formed strike a target
containing the coating. The target surface sputters off atoms which
are attracted to an anode which contains the substrate. A method
such as this is considerable improvement over several known
methods, but the relatively large amount of ionized gas creates an
arc effect and gives off considerable heat, even though this method
has the advantages of somewhat greater uniformity and good adhesion
of the coating material to the substrate. Another, more modern,
method is so-called triode sputtering, wherein the substrate is
rendered positive, and electrons from a hot cathode are directed at
the target, following which coating atoms are sputtered to the
substrate which was desired to be coated. Although this method of
coating possesses a number of advantages, it is in some cases not
commercially desirable for coating many types of substrates,
especially such as razor blades; since although this method uses
less argon than other methods, and a longer mean free path is made
possible for improved efficiency, this method is best suited for
transferring only metals and alloys thereof, and still relies for
its source of energy on a hot wire cathode, which may introduce
ionic contaminants of tungsten, for example. In addition, the
coated surface requires finish grinding after plating.
All of the foregoing known methods of deposition of thin films have
been considered and, although useful, they are not considered
perfected for coating products having extremely fine cutting edges.
Some of the purposes for which such coating is desired will now be
discussed.
It has always been desired, in the razor blade art, to form a very
sharp blade edge suitable for shaving, and to have that edge
combine the advantages of corrosion resistance and longevity, as
well as presenting a smooth and lubricious surface to the face of a
shaver. Thus, it is desired to have a relatively
corrosion-resistant blade having an extremely sharp surface and
having the blade made from an extremely hard or tough material
which would resist dulling. Thus, an ideal razor blade would
combine the advantages of a long life in use as well as long shelf
life, combined with an extremely sharp cutting edge and maximum
smoothness for purposes of shaving comfort.
In the razor blade art, it is well known, in the interest of
shaving comfort, to coat a portion of the blade adjacent the
cutting edge with a lubricious plastic, such as a fluorocarbon
polymer, for example, polytetrafluoroethylene ("Teflon") or a
polymer such as polyethylene, or the like. Likewise, in the last
several years, razor blades made from more corrosion resistant and
tougher materials than those previously used have come into common
use and have been accepted on a large scale commercially. Thus, the
use of stainless steel for making razor blades is now quite common.
However, it is likewise known that stainless steel is not the
perfect material for making an ideal razor blade, but one which, at
present, best combines the advantages of acceptable competitive
cost, easy processability, corrosion resistance and durability of
the shaving edge imparted thereto. However, even in spite of the
great success of the stainless steel blade, there has been a demand
in the razor blade art for a razor blade which would harmonize, at
reasonable cost, the seemingly contradictory requirements of using
a very hard, tough metal substrate for securing a long wearing
blade edge, and using metals which, although sufficiently hard and
tough to last for a long time, may nonetheless be readily ground to
an extremely fine sharp edge, free from brittleness and
microscopically jagged edges or voids in the sharpened surface.
Thus, a greatly improved razor blade would be one in which the
blade could be manufactured from conventional materials, such as
ordinary steel or stainless steel, and could then be given a very
fine smooth metal surface coating, which would not require further
finishing of the coating metal to impart these characteristics to
the edge. However, since no known materials combine these
advantages, a great deal of effort has been placed on developing
methods and apparatus for coating blade edges of existing type
razor blades. However, metal coating already sharpened blade edges
by conventional methods has always resulted in an edge which
requires further finishing, and the application of a hard coating,
such as chromium, has resulted in a blade which was very brittle
near the edge portions, and which was very difficult to grind down
or polish to the desired degree of smoothness, especially at a
reasonable cost.
Thus, there has been a great demand for a simple and economical
method of placing a fine, hard, extremely smooth coating on a
finished razor blade edge portion which would not require further
treatment, but which would impart to such a blade edge the
desirable characteristics of smoothness and hardness as well as
corrosion resistance.
The invention of the applicant, namely, the method of coating the
blade edge by means of radio frequency-induced plasma sputtering,
and the development of an apparatus for carrying out this method,
accomplished its objects, namely, the provision of a method and
apparatus for improved surface coating of razor blades and like
substrates.
SUMMARY OF THE INVENTION
In view of the shortcomings of prior art methods and apparatus for
coating razor blades, it is an object of the invention to provide
an improved method and apparatus for placing a very then, very fine
coating, either organic or inorganic, on a sharpened metal surface
after sharpening such a surface, to provide an improved blade or
the like.
A further object of the present invention is to provide a method of
coating a desired substrate with a desired coating material at low
temperatures and at a reasonable cost, and to attain an extremely
uniform coating which needs no further treatment to present a sharp
cutting edge to the user.
Another object is to provide an apparatus for carrying out radio
frequency-induced plasma sputtering of a metal, metal oxide or
other metal compounds or non-metal coating material onto a razor
blade.
Still another object of the invention is to provide a coating
apparatus which is simple and compact to facilitate ready inclusion
and use thereof in a high vacuum chamber.
Another object is to produce a razor blade or like article with a
sharp cutting edge which is suitable, after being treated as
described herein, to be further processed as by coating with a
polymer, without the need for additional intermediate preparation
steps.
By "sputtering," as used herein, is meant the slow disintegration
of a target under the bombardment of ionized gas molecules, and,
more particularly, the disintegration of a coating material which
is placed on the target and transferred to a substrate after being
"sputtered" from the target. The coating material is moved from the
target plates to the substrate by a so-called "RF induced plasma
sputtering" process.
The present invention achieves its objects and overcomes the
disadvantages of the prior art by providing a method which includes
the steps of providing a sputtering module which includes two flat
electrode plates arranged to form a peak at one end thereof and an
opening opposite the peak, placing target plates containing the
coating material in front of the electrode plates, providing
carrier means for supporting a plurality of articles to be coated,
drawing a very high vacuum in the area surrounding the sputtering
module and the carrier means, impressing a radio frequency current
across the electrode plates and electronically biasing the carrier
means with respect to the electrode plates, "leaking" an inert gas
into the region between the plates and passing the articles to be
coated across the opening between the peaked plates so that
electron bombardment of the gas ionizes the gas, the ions strike
the target plates, sputtering the surface material therefrom, and
the articles are uniformly coated by the sputtered material.
The method is advantageously performed by an apparatus which
includes a drum or like means for carrying a plurality of articles
holders past the sputtering module, and exposing a desired portion
of the blades or other articles held on the carrier to the opening
in the sputtering module in a timed relation so as to obtain a
coating of desired uniformity, thickness and adhesion to the
article. A preferred embodiment includes a drum holding a plurality
of rotating hubs, and an epicyclic drive mechanism for rotating
each of the articles carriers into a desired location as each hub
unit passes the sputtering module, by utilizing relative rotation
of the drum and hub assemblies.
In one embodiment, a metal coating is sputtered onto the edge
portions of razor blades, and in other embodiments, organic
polymers or other high-molecular weight coatings are transferred to
a substrate, in some cases with simultaneous partial chemical
breakdown, rearrangement, or other chemical or physical reaction
during the sputtering process, and in still further embodiments,
metal oxides, alloys, or other metal compounds are transferred, or
simultaneously formed and transferred.
Other and further objects and advantages of the present invention,
including the manner of attainment thereof, will become more
apparent when considered in conjunction with a description of the
preferred embodiments of the invention described further
herein.
In keeping with the teachings of the present invention, a number of
different products were made according to the processes set forth
in detail below.
EXAMPLE 1
The apparatus shown in FIGS. 1 to 4 of U. S. Pat. No. 3,635,811 was
used with a bell jar comprising the outer vacuum chamber. U. S.
Pat. No. 3,635,811 is incorporated herein by reference. A plurality
of razor blades were carefully cleaned, as by immersing them in,
and evaporating therefrom, a solvent, such a trichloroethylene or
other suitable solvent. The blades were placed on holding means,
such as a bayonet unit shown.
A pair of target plates were prepared by taking two mild steel
plates, placing a heavy chromium plating on one surface of each
plate by a conventional electrolytic deposition method. The plating
may be of any desired thickness. Thereafter, these plates were
secured to the inside surfaces, respectively, of the electrode
plates.
Thereafter, a mechanical "roughing" pump was turned on, evacuating
most of the air from the vacuum chamber to a pressure of 100
microns approximately. By means of an oil diffusion pump and cold
trap, the pressure inside the air chamber was further evacuated
until a pressure of 1 .times. 10.sup..sup.-5 millimeters of mercury
was attained.
Thereafter, by means of a needle valve or like so-called leak valve
argon gas was allowed to be introduced into the chamber until
pressure was raised to 3 .times. 10.sup..sup.-3 millimeters of
mercury(Torr).
Thereupon, the radio frequency generating unit such as that shown
in FIG. 6 of U. S. Pat. No. 3,635,811 was actuated, and a radio
frequency of 13.56 megacycles per second was impressed on the
plates, the matching network assocaited with the RF unit being
adjusted or tuned so as to minimize the impedance mismatch caused
by the lead of target plates. Charging of the plates with the R. F.
current immediately causes a plasma to produced between the plates.
Thus, the electrons emmited by the plates rush back and forth
therebetween at a frequency of about thirteen million complete back
and forth cycles per second and many of these electrons strike the
atoms of argon gas disposed between the plates. Because of the
argon atoms or other inert gas atoms, are very massive in relation
to the mass of electrons, the argon atoms or molecules themselves
are not substantially moved by the movement of the electrons or
attracted by the charge which builds up on or closely surrounding
the plates. However, the high frequency electrons bombarding the
argon gas cause ionization thereof, and upon ionization each
positive ion of argon is strongly attracted, by reason of the high
negative charge, to one or the other of the plates. This high space
charge accelerates the argon atoms toward the electrode with great
energy. However, the ionized atoms strike the target material which
is placed on the target plate placed immediately in front of the
electrode. The momentum with which the ionized argon atom strikes
the target plate may be sufficient to sputter one or more atoms or
molecules off the target plate.
When initial ionization takes place, the pressure is reduced by
reducing the rate of addition of argon, to approximately 1.5
.times. 10.sup..sup.-3 mm of mercury. Thereupon, the RF energy
input is raised to a value of 600 watts forward power.
A DC bias of 1800 volts is built up between the RF system and the
blade or article carrying means, this bias resulting from the
negative space charge on the plates in relation to the potential of
the carriers, which are fully insulated from the plates. The bias
occurs because of the intrinsic characteristics of the circuit,
that is, the plates take on, or appear to take on, a strong
negative charge. While the particles which are sputtered from the
target plate are in a neutral state, that is, they are not ionized,
and therefore are not attracted to the substrate or article to be
coated by reason of the bias between the plates and the article
carrier, a certain degree of bias is desirable to prevent
positively charged argon or like ions from striking the articles,
since this would result in "resputtering" either the substrate or
the coating sought to be applied.
Thus, the bias between the plates and the carrier is desirable, but
its value is not of critical importance to the invention.
Thereafter, the amount of forward power in the system is then
adjusted by altering the amount of argon introduced into the system
by a very minute adjustment. It is preferred that after arriving at
a pressure of between 1 and 2 .times. 10.sup..sup.-3 millimeters,
and adjusting the impedance matching network, there will be about
500 to 600 watts forward power and about 100 watts or less of
reflected power, leaving a net power input into the "plasma peak"
or to the two plates and the area therebetween of about 500 to 600
watts, and preferrably about 510 to 550 watts. Power levels of
greater or lesser quanity will directly affect sputtering rate.
Under these conditions, sputtering will proceed for a period of
approximately four minutes, and a coating having a thickness of
about 625 Angstroms (A.) will be deposited upon a flat surface, and
half that thickness, namely 264 Angstroms, will be deposited on the
edge portions of a razor blade, disposed with the razor edge
portion thereof directed generally to the area between the plasma
peak.
The razor blades coated by the process just set forth were shown to
process an extremely fine, pore-free and uniform coating of
chromium, rendering them resistant to rust and corrosion. Such
blades, which possessed a very sharp or keen edge, also required no
further honing or other treatment, and were ready for next process
stage when removed from the vacuum chamber.
Although the exact reasons for the success of the sputtering
apparatus and method of the present invention, are not entirely
understood, it is believed that, because the coating material is
liberated from the target plate in substantially atomic or
molecular size particles, the adhesion thereof to the substrate or
articles to be coated is not only very strong but, since the
charges possessed by the coating material particles are the same
and such charges tend to repel each other, the individual atoms
each tend to seek out one particular location in the substrate and
repel other atoms from that immediate area until the entire
substrate is uniformly covered and thus attains a fine, even
coating surface.
By "charges," as used in the preceding paragraph, referring to the
charges on the particles of the coating material, it will be
understood that these particles are not ionized, but merely have a
slight electrostatic or like surface charge of an extremely small
magnitude.
In fact, if a physical analogy might be made, the sputtered atoms
or molecules act, upon contacting the substrate or article to be
coated, somewhat as droplets of water when placed or spilled on hot
frying pan or the like. Thus, in this analogy, the droplets of
water would be compared to atoms having a surface charge, and the
fine subdivision and rapid movement thereof is characteristic of
the atoms striking the substrate. Thus, the atoms being surrounded
by their own charge, much as the heated droplets of water are
surrounded by a vapor phase of their own, tend not to coalesce in
one location but to spread themselves about in a random manner.
Thus, a razor blade like article coated according to the present
invention is characterized by an extremely thin but very smooth
coating, since the method apparently creates a coating in which the
deposited or coating material is placed upon the substrate
substantially literally one molecule at a time.
EXAMPLE 2
It is also well known, in the razor blade art to coat a portion of
a razor blade in an area which is very close to the cutting edge
with a polymer having lubricious characteristics, such as a
polytetrafluoroethylene or like fluorine-or chlorine-containing
polymers, or polyethylene, or other lubricious plastic material.
However, prior methods have involved suspending the polymer in a
solvent or the like and, after placing a liquid phase coating on
the blade, evaporating the solvent and curing the polymer. However,
as set forth below, the present method may be used for direct
polymer coating of blades or the like. Initially, steel plates or
blades approximately 6 inches by 9 inches in size and about one
fourth of an inch in thickness where sprayed with a film of
polytetrafluoroethylene and the coating thus sprayed was baked out
or cured in a reducing atmosphere for 20 minutes at 700 degrees
F.
It is preferred to perform this operation in a very high vacuum to
avoid entrapping gases in the coating which could create a reaction
with the polymer or other materials present in the chamber or
interfere with the generation of the plasma.
These plates were clipped into position just inside and adjacent
the plates into the position shown in FIG. 1 of U. S. Pat. No.
3,635,811.
Next, razor blades were cleaned as set forth above, in Example 1,
by immersing in a solvent or the like.
Next, the bell jar was evacuated by means of mechanical and
diffusion pumps to a pressure of 1 .times. 10.sup..sup.-5
millimeters of mercury. Thereupon, argon was introduced until the
pressure attained a level of 3 .times. 10.sup..sup.-3 millimeters
of mercury, and a plasma was achieved at this pressure by
impressing approximately 100 watts of R.F. energy across or into
the peak defined by the plates. Once ionization took place, that
is, once the plasma was established, the argon pressure was reduced
to an operating level of 1.5 .times. 10.sup..sup.-3 millimeters of
mercury.
Thereupon, the R.F. energy was increased to a net power of about
275 watts, that is, about 300 watts forward power and 25 watts
reflected power. In this example, the bias between the grounded
carrier unit and the plates was approximately 800 volts of
self-biased D.C. In this example, the process was continued for a
period of approximately 5 minutes. Under these conditions,
approximately 1200 A. of a plastic material were deposited on an
optical flat which was placed in the chamber near the articles to
be coated, and the coated articles contained a corresponding amount
of plastic material, depending on their configuration that is, on
the amount of surface and angle thereof presented to the plates. A
coating such as this may be deposited in any desired thickness,
preferably, in this case about 200 to 2000 A. in thickness.
Analysis of the films deposited by this method, by both intra red
spectroscopy and nuclear magnetic resonance (NMR), showed that the
deposited plastic was of different composition than that of the
plastic which was placed on the plates, differing in that some of
the characteristic C-F (Carbon-fluorine) bands had disappeared, and
in that the molecular weight of the coating material had been
reduced by an order of some of two to five times. The resulting
polymer deposited on the substrate or coated article was
nevertheless a somewhat similar polymer, containing the same
elements even though the exact crystal structure of the initial
polymer has been considerably altered. Thus, this example
demonstrates the use of the novel method for simultaneously
depositing and altering or rearranging a polymer in one step.
EXAMPLE 3
In this example, all the conditions were the same as those set
forth in Example 1; the coated material was chromium, a plurality
of blades were placed on the bayonet or carrying unit, and a
plurality of these carrier units were inserted into the hubs.
Thereafter, the sputtering process was carried out in accordance
with the conditions of Example 1, except that it was continued for
a longer time, and the entire carrier unit was revolved through two
complete cycles, thus exposing the top and bottom edges of the
plurality of razor blades held in each bayonet unit to the plasma
peak or sputtering module for the same length of time and at the
same angle as all the other blades. The process was timed so that a
coating of approximately 200 to 300 A. of chromium was deposited on
the edge portion of each razor blade. In this example, the argon
was continually admitted during the process, maintaining the
operating pressure set forth in the first example and the
sputtering took place continuously until each bayonet unit had made
two passes beneath the sputtering module. The drum unit was
revolved at a rate of one quarter of a revolution per minute and
two complete cycles of rotation thus coated both edges of all
baldes in eight minutes of operation. The coating thickness
referred to herein and in Example 1 are merely illustrative, since
these coatings may be of any desired thickness.
EXAMPLE 4
In this case, a process similar to that set forth in Example 1 was
carried out, except that the deposited material, instead of being
metallic chromium, was an alloy iron, nickel and chromium, one
brand of which is known as "Nichrome." After carrying out the
process according to the conditions set forth in Example 1, it was
discovered that the article, contained a coating of the alloy which
was placed on the target plates in the same exact composition as
the composition of the alloy on the plate. Thus, the method
demonstarated its ability to transfer an alloy from the target to
the substrate without altering the composition of the alloy.
EXAMPLE 5
In this example, the conditions were the same as those set forth in
Example 3, except that the coating material was the alloy of
Example 4.
EXAMPLE 6
In this example, conditions were the same as those in Example 1 or
4, except an iron carbide material, having a very hard surface, was
coated onto a razor blade by the same process.
EXAMPLE 7
A method such as that referred to in Example 1 was carried out,
with all conditions thereof remaining the same, except that during
the time the argon was leaked into the bell jar, a small amount of
oxygen was allowed to enter the jar. By allowing sufficient oxygen
to enter the jar to react with the chromium, but not enough oxygen
so as to substantially diminish the vacuum in the system or to
interfere with the creation of the plasma, it was discovered that a
coating of chromium oxide was able to be placed on the blades.
Thus, this method demonstrates the ability of the method of the
present invention simultaneously to carry out coating deposition
and to allow a chemical reaction between the coating material and
another product introduced into the vacuum chamber.
It is believed that, since the sputtered coating material is
generally in a monoatomic or monomolecular form, the availability
of individual atoms or molecules for reaction is great, and the
probabilities of the desired reaction taking place are excellent.
Thus, a principal advantage of this method is that it makes
possible what is essentially a gas phase reaction at temperatures
greatly below the vaporizing or sublimation temperatures of
refractory materials, such as, for example, the types of metals
referred to herein.
Those blades referred to in the preceding examples in which a metal
or metal-containing compound was applied to the edge were suited to
receive an additional coating of plastic, over the newly coated
edge, either by a subsequent sputtering operation or by
conventional methods.
As pointed out above, a principal advantage of this method is that
no treatment subsequent to sputtering is required to prepare the
coated article for use or for a subsequent coating operation.
Particularly in the case of razor blades, this is a great
advantage, since, in the past, two honing operations were required
for a blade with a coated edge, and honing is an operation which
adds considerably to the cost of a blade.
The above described method makes possible the application of films,
whether metallic, inorganic, or organic, of thickness which are
thinner than those previously achieved in the cutting edge and
razor blade art, for example.
As set forth in Example 1, a razor blade prepared according to the
present invention will have a coating, for example, of a thickness
of 100 to 600 Angstroms, that is, between one and six
one-hundredths of a micron. Thus, although it has been known to
apply metal coatings, for example, by evaporation, in thickness of
somewhat less than a micron, it is believed that it is not
heretofore known to coat a blade with a thickness of metal of one
to six one-hundredths of a micron.
It is believed that one reason that such a thin coating is
satisfactory is that the sputtered molecules have such momentum,
when sputtered from the target, that they are firmly held by the
substrate, and, in addition, since no subsequent honing or
stropping is required it is not necessary to add additional
thicknesses of material, which would then merely be grounded away
in a resharpening operations.
Likewise, coating the fluorocarbon, hydrocarbon, or other polymer
over an ordinary carbon steel blade edge, over a stainless steel
blade edge, or even over an edge coated with chromium according to
the method of the present invention, or otherwise, is believed
novel in that such coating may be applied with a thickness of as
little as 200 Angstroms or less, or as large as 1200 to 2000
Angstroms or more. Such coating thicknesses are much smaller than
those presently able to be achieved by other methods. In addition,
blades having such thin coatings have not been heretofore known,
since it has not been possible to apply such a thin coating in a
reproductible manner.
Although the reason therefor is not clearly understood, it is known
that coatings such as those described herein may be applied to the
cutting edges of blades, as described, without joining the edges
together. It is possible that, since the electrode plates are
disposed at an angle relative to the faces which define the cutting
edges of the blades or other instruments, that sputtered molecules
do not ordinarily have a vertical trajectory, and thus do not tend
to fly vertically into the "valleys" between blade edges, at least
in substantial numbers compared to the number striking the faces
near the cutting edges. At any rate, there has somewhat
unexpectedly been no problem with blades sticking together; this is
another advantage of the invention which facilitates treatment of
large numbers of blades at low cost.
It will thus be seen that the present invention provides a novel
apparatus, method and articles having novel advantages and
characteristics, including those hereinbefore pointed out and
others which are inherent in the invention.
Having completed a disclosure of my invention, in keeping with the
patent statutes, so that one skilled in the art may practice the
invention, I contemplate that certain variations may be made herein
without departing from the spirit of the invention or the scope of
the appended claims.
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