U.S. patent number 3,829,969 [Application Number 05/087,170] was granted by the patent office on 1974-08-20 for cutting tool with alloy coated sharpened edge.
This patent grant is currently assigned to The Gillette Company. Invention is credited to Ben H. Alexander, Irwin W. Fischbein, Aiyaswami S. Sastri.
United States Patent |
3,829,969 |
Fischbein , et al. |
August 20, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
CUTTING TOOL WITH ALLOY COATED SHARPENED EDGE
Abstract
A protective layer of an alloy of platinum and chromium is
formed on a substrate by sputtering, this metal alloy providing a
hard, corrosion resistant, protective layer for the substrate.
Inventors: |
Fischbein; Irwin W. (Canton,
MA), Alexander; Ben H. (Brookline, MA), Sastri; Aiyaswami
S. (Malden, MA) |
Assignee: |
The Gillette Company (Boston,
MA)
|
Family
ID: |
27489169 |
Appl.
No.: |
05/087,170 |
Filed: |
November 5, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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47664 |
Jun 19, 1970 |
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865634 |
Oct 13, 1969 |
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845142 |
Jul 28, 1969 |
3682795 |
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Current U.S.
Class: |
30/346.54;
204/192.16; 420/427; 420/430; 420/461; 428/670; 428/932; 30/346.53;
420/424; 420/428; 428/656; 428/926 |
Current CPC
Class: |
C23C
30/00 (20130101); B26B 21/54 (20130101); C23C
14/165 (20130101); B26B 21/58 (20130101); C23C
14/35 (20130101); Y10S 428/932 (20130101); Y10S
428/926 (20130101); Y10T 428/12778 (20150115); Y10T
428/12875 (20150115) |
Current International
Class: |
C23C
14/35 (20060101); B26B 21/58 (20060101); B26B
21/54 (20060101); C23C 30/00 (20060101); B26B
21/00 (20060101); C23C 14/16 (20060101); B26b
021/54 () |
Field of
Search: |
;29/183.5,196,198
;204/192,298 ;30/346.53,346.54,165 ;75/176 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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457,378 |
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Jun 1949 |
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CA |
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1,184,428 |
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Mar 1970 |
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GB |
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Other References
Hansen, Max, et al.-"Constitution of Binary Alloys" N.Y.,
McGraw-Hill; 1958 pp. 548, 552-556;TA490H27aE1958..
|
Primary Examiner: Douglas; Winston A.
Assistant Examiner: Crutchfield; O. F.
Parent Case Text
This application is a continuation-in-part of our copending patent
application Ser. No. 47,664, filed June 19, 1970 and now abandoned
and entitled "Razor Blades" which in turn was a
continuation-in-part of prior patent application Ser. No. 865,634,
filed Oct. 13, 1969 and now abandoned, which in turn was a
continuation-in-part of prior application Ser. No. 845,142, filed
July 28, 1969 now U.S. Pat. No. 3,682,795.
Claims
What is claimed is:
1. A cutting tool comprising a substrate having a sharpened edge
and an alloy film of composition different from said substrate on
said sharpened edge, said alloy film having a microhardness of at
least about 750 DPHN and being an intermetallic compound with
either the ordered A15 cubic structure or the tetragonal ordered
structure or a composition with proportions within about .+-.5
weight percent of such a compound, said alloy film consisting of a
first metal selected from the class consisting of iridium, osmium,
palladium, platinum, rhenium, rhodium, and ruthenium and a second
metal selected from the class consisting of chromium, manganese,
molybdenum, niobium, tantalum, titanium, tungsten, and
vanadium.
2. An article according to claim 1 in which said first metal is
selected from the class consisting of iridium, osmium, platinum,
rhenium, rhodium, and ruthenium and said second metal is
chromium.
3. An article according to claim 1 wherein said second metal is
selected from the class consisting of chromium, molybdenum,
niobium, titanium, and vanadium.
4. An article according to claim 1 in which said first metal is
selected from the class consisting of platinum, iridium, and
osmium.
5. An article according to claim 1 in which the alloy film is at
least as hard as said substrate.
6. An article according to claim 1 wherein the alloy film on said
substrate has a maximum crystallite size of less than 1,000A.
7. The article as claimed in claim 6 wherein said second metal is
chromium.
8. An article according to claim 1 in which the alloy film is
composed of platinum and chromium.
9. An article according to claim 8 in which the alloy film is
composed of 21-27 atomic per cent platinum and the remainder
chromium.
10. An article according to claim 1 in which the alloy film is
composed of platinum and titanium.
11. The article as claimed in claim 1 wherein said alloy film has a
thickness of at least 50A.
12. The article as claimed in claim 1 wherein the thickness of said
alloy film is in the range of 100-400A.
13. The article as claimed in claim 1 wherein said substrate is
steel.
14. A razor blade comprising a substrate having a sharpened edge
and an alloy film of composition different from said substrate on
said sharpened edge, said alloy film having a microhardness of at
least about 750 DPHN and being at least as hard as the underlying
substrate material and being an intermetallic compound with either
the ordered A15 cubic structure or the tetragonal ordered structure
or a composition with proportions within about .+-.5 weight percent
of such a compound, the intermetallic compound consisting of a
first metal selected from the class consisting of iridium, osmium,
palladium, platinum, rhenium, rhodium, and ruthenium and a second
metal selected from the class consisting of chromium, manganese,
molybdenum, niobium, tantalum, titanium, tungsten and vanadium.
15. The blade as claimed in claim 14 wherein said second metal is
selected from the class consisting of chromium, molybdenum,
niobium, titanium, and vanadium.
16. The blade as claimed in claim 14 wherein said first metal is
selected from the class consisting of iridium, osmium, platinum,
rhodium and ruthenium, and said second metal is selected from the
class consisting of chromium and titanium.
17. The blade as claimed in claim 14 wherein said first metal is
selected from the class consisting of iridium, osmium and platinum
and said second metal is chromium.
18. The blade as claimed in claim 14 wherein said alloy film is
composed of 20-30 atomic per cent platinum and the remainder
chromium.
19. The blade as claimed in claim 14 wherein said alloy film is
composed of 21-27 atomic per cent platinum and the remainder
chromium.
20. The blade as claimed in claim 14 wherein said alloy film has a
thickness of less than 600A.
21. The blade as claimed in claim 14 wherein the thickness of said
alloy film is in the range of 100-400A.
22. The blade as claimed in claim 21 wherein the corrosion
resistance of said alloy film is such that the cutting edge of said
blade shows no sign of corrosion after immersion in concentrated
hydrochloric acid for one minute.
23. The blade as claimed in claim 22 wherein said second metal is
chromium.
24. The blade as claimed in claim 23 wherein said alloy film is
composed of 20-30 atomic per cent platinum and the remainder
chromium.
25. The blade as claimed in claim 24 wherein said alloy film is
composed of 21-27 atomic per cent platinum and the remainder
chromium.
26. The blade as claimed in claim 14 and further including a thin
chromium containing overlayer on said alloy film, said overlayer
being of a different composition from said alloy film.
27. The blade as claimed in claim 22 wherein said first metal is
selected from the class consisting of iridium, osmium and platinum
and said second metal is chromium.
28. The blade as claimed in claim 27 wherein said alloy film is
composed of 21-27 atomic per cent platinum and the remainder
chromium.
Description
SUMMARY OF INVENTION
This invention relates to protective materials and to articles with
protective metal layers which have excellent corrosion and wear
resistant characteristics, and to improved methods and apparatus
for manufacturing such articles.
Frequently the surface of an article requires protection against
both mechanical wear and corrosion. Such surfaces include the
interiors of piston chambers, for example in internal combustion
engines; and surfaces of devices such as pumps or valves that are
inserted into the human body. In the latter case, the device must
operate reliably and without significant mechanical wear for years
and not corrode or contaminate the system in which it is
disposed.
Another such surface is the cutting edge of a razor blade which is
sharpened with precision and is subjected both to corrosive
atmospheres and to substantial mechanical force during shaving. The
faces or sides of cutting edges of razor blades extend back from
the ultimate edge and may comprise two or more "facets" formed by
successive grinding or honing operations and intersecting each
other along zones generally parallel to the ultimate edge. The
final facet, that is the facet immediately adjacent the ultimate
edge, may have a width of as little as 0.0003 inch or even less,
while the thickness of the ultimate edge is generally less than
6,000A and preferably less than 2,500A. Due to its thinness, the
ultimate edge is extremely susceptible to mechanical failure and,
particularly in the case of carbon steel, to corrosion failure. It
has been proposed to apply a coating of a corrosion resistant metal
such as gold, rhodium or chromium to the sharpened edge of a razor
blade by evaporation or sputtering. However, noble metals have not
been satisfactory as they tend to break away from the underlying
shaving edge under the abrasion forces encountered in shaving, such
tendency rendering the blades commercially unsatisfactory. Further,
a shave facilitating polymeric fluorocarbon coating is frequently
cured on the blade edges by exposing the blades to elevated
temperatures, e.g., 550.degree. to 800.degree. F. Such temperatures
have a softening effect on the underlying blade metal, which
softening adversely effects the shaving properties of the blades.
In the case of razor blades, therefore, the metal film, in addition
to having hardness and corrosion resistance characteristics, should
maintain significant hardness at fluorocarbon sintering
temperatures even though the underlying steel softens, should have
adhesion compatibility with both the underlying steel and the
overlying polymeric coating so that all the layers remain firmly
adhered to one another throughout the shaving life of the blade and
should not otherwise have an adverse effect on shaving
characteristics.
It is a general object of this invention to provide novel and
improved articles which have improved mechanical properties and
especially improved corrosion and wear resistance and novel and
improved methods and apparatus for producing such articles.
A more specific object of the present invention is to provide a
substrate with a hard protective metal film having improved
corrosion resisting properties which is firmly adherent to a
substrate surface and provides a sturdy base for polymeric coatings
which are formed at elevated temperatures.
A further object of the invention is to provide novel and improved
methods for providing an article having superior wear and corrosion
resistant properties.
Another object of the invention is to provide novel and improved
methods and apparatus for improving the wear and corrosion
resisting properties of a substrate in a mass production process
and in a manner that does not impair the quality of the underlying
substrate.
A still further object of the invention is to provide a novel and
improved razor blade which possesses superior shaving
properties.
Another object of the present invention is to provide a metal film
on a razor blade which has improved corrosion resisting properties,
which is firmly adherent to the surfaces of the blade edge and
which provides a sturdy and compatible base for polymeric coatings
which are formed at elevated temperatures.
In accordance with the invention there is provided a substrate with
a firmly adherent film of alloy of a first metal selected from the
class consisting of iridium, osmium, platinum, palladium, rhenium,
rhodium and ruthenium (hereinafter termed an N metal) and a second
metal selected from the class consisting of chromium, manganese,
niobium, molybdenum, tantalum, titanium, tungsten, vanadium and an
N metal different from the other metal of the alloy, (hereinafter
termed a strengthening metal); the class consisting of chromium,
molybdenum, niobium, titanium, vanadium and an N metal being a
preferred class. Particularly advantageous are those alloy
compositions that form an intermetallic compound with either the
ordered A15 cubic structure or the tetragonal ordered (sigma phase)
structure and alloy compositions within about .+-.5 weight percent
of these compounds, those alloys having excellent heat
stability.
In the case of platinum-chromium alloys, a preferred range of
platinum content is 15-65 atomic percent and where the environment
of use is particularly corrosive it is preferred that the platinum
content be at least 21 atomic percent.
The alloy of the invention has a micro hardness greater than 750
DPHN and an extremely fine grained structure, the crystallite size,
as determined by electron microscopy or electron diffraction
techniques, being less than one thousand Angstroms. For example,
the crystallite size of thin film platinum-chromium alloys in
accordance with the invention in as sputtered condition is less
than fifty Angstroms. Substrates having alloy films on them in
accordance with the invention exhibited no sign of corrosion after
immersion in concentrated hydrochloric acid for one minute. A
platinum-chromium alloy in accordance with the invention having a
platinum content of 21 atomic percent has a dissolution rate in
boiling hydrochloric acid of 0.008 mils per minute, which may be
contrasted with a dissolution rate of 1,000 mils per minute for
pure chromium in boiling hydrochloric acid. In typical
applications, the alloy film in accordance with the invention is at
least fifty Angstroms in thickness, is continuous, and is of
uniform thickness.
Where the substrate is the sharpened edge of a steel razor blade,
the M.sub.3 N compound is particularly advantageous as it has
greater heat stability than the underlying steel. For example, the
hardness of a Cr.sub.3 Pt alloy film on a razor blade in accordance
with the invention is substantially independent of heat treatment
temperatures up to 1,200.degree. C. In such a platinumchromium
alloy film, a preferred range of platinum content of the film is
15-30 atomic percent and particularly advantageous results are
obtained with a film having a platinum content of 21-27 atomic
percent. The alloy film in accordance with the invention is at
least as hard as the underlying blade metal and should not exceed
600A in thickness, a preferably range being 50-500A and the best
results being obtained with a thickness in the range of 100-400A.
Further, where a fluorocarbon shave facilitating coating is
utilized, alloy films that employ either chromium or an N class
metal as the strengthening metal provide most satisfactory coating
adherence. In cases where the adhesion of the fluorocarbon coating
to the alloy appears to be inadequate, (i.e., W-Pt) the benefits of
the hard alloy coating can be obtained by the use of a very thin
(about 75A or less) overlayer of the Cr.sub.3 Pt alloy as an
interfacial bonding agent.
In the manufacture of razor blades, the alloy film should be
applied with processes and apparatus that permits production of
large quantities of razor blades with a minimum of additional
processing steps, and accordingly, a further object of the
invention is to provide novel and improved methods and apparatus
for placing a metal alloy film having superior corrosion resistant
properties on the sharpened edges of razor blades with controlled
uniformity.
Another object of the invention is to provide novel and improved
apparatus for placing a film of improved corrosion resistant alloy
on the sharpened edges of razor blades in a mass production process
and in a manner that does not impair the quality of the sharpened
edges.
Still another object of the invention is to provide a novel and
improved commercial production blade treatment system in which the
sharpened edges of razor blades are cleaned and a thin film of a
corrosion resistant metal alloy that is at least as hard as the
underlying blade metal is applied to the cleaned sharpened blade
edges.
A blade treatment system in accordance with this feature of the
invention includes an evacuable chamber in which is disposed
structure for receiving one or more stacks of razor blades, the
blades in each stack being disposed in face to face relationship
with their sharpened edges in alignment. Also disposed within the
chamber is a source of metal that extends along a line parallel to
the exposure axis (or plane) of each razor blade stack. The source
includes an N metal and a strengthening metal in metallurigically
separate form from the N metal. The source may take various forms,
for example it may be a sintered compact of the metals of which the
alloy is to be formed, or an assembly of one or more segments of
the strengthening metal component of the alloy to which
appropriately spaced segments of the N metal component of the alloy
are secured. In processing the blades, after the blade edges are
cleaned in the vacuum chamber, the metal source is energized in a
reduced pressure gaseous environment to transfer the metals from
the source and form on the blade edges a thin film alloy of the
metals of the source. A preferred method of forming the alloy film
on the blade edges is to subject the composite metal source to an
ion bombardment process ("sputtering") to transfer metal atoms to
the sharpened blade edges. Other deposition techniques, such as
evaporation utilizing an electron gun source or induction heating
may also be used where appropriate. Where a fluorocarbon polymer is
subsequently sintered on the alloy film, an inert gas such as argon
or nitrogen is preferably employed as the sintering atmosphere,
although other sintering atmospheres, such as cracked ammonia or
hydrogen may be utilized, particularly with alloys with relatively
small amounts of the N metal.
This invention is particularly useful in providing an improved thin
protective metal alloy film on the sharpened edges of razor blades,
which thin film does not have an adverse effect on shaving
characteristics of the blade and which does not require further
mechanical working of the blade edge area to provide satisfactory
first shave quality. A wide range of blade materials may be used,
specific razor blade steel compositions with which the invention
may be practiced including the following:
COMPOSITION IN % ______________________________________ C Cr Mo Si
Ni ______________________________________ 1.25 .2 -- .2 -- 1.00 6.0
-- 1.4 -- .96 13.9 -- .3 -- 65 10.5 1.0 .3 -- .58 14.0 -- .3 -- .40
13.5 1.25 .3 -- .09 17.0 .70 1.2 8.0
______________________________________
The preferred metal alloy coatings on the edges of the blades of
the invention are significantly harder than the blade bodies
(having micro hardnesses of up to about 1,700 DPHN), remain harder
than prior art commercial blades after the blades are subjected to
polymer curing temperatures in the range of 550.degree.-800.degree.
F, and have excellent corrosion resistance.
Other objects, features and advantages of the invention will be
seen as the following description of particular embodiments of the
invention progresses, in conjunction with the drawings, in
which:
FIG. 1 is a sectional view of a form of apparatus employed in the
practice of the invention;
FIG. 2 is a sectional view of the apparatus shown in FIG. 1, taken
along the line 2--2 of FIG. 1; and
FIG. 3 is a graph indicating characteristics of an alloy in
accordance with the invention.
DESCRIPTION OF PARTICULAR EMBODIMENTS
The sputtering (ion bombardment) apparatus shown in FIG. 1 includes
a stainless steel cylinder chamber 10 18 inches in diameter and 32
inches high mounted on base 12. Base 12 is coupled through port 14
to a suitable vacuum system (not shown). A butterfly valve that has
an aperture one inch in diameter is disposed downstream of port 14
and may be moved to closed position during sputtering to reduce
back streaming of the diffusion pump. Mounted in chamber 10 on ring
assembly 16 for rotation about vertical axes are eighteen blade
stack support structures 18. Assembly 16 is isolated electrically
from base 12 by six post structures 20. Each blade stack support
structure 18 includes a base structure 22 that has a recess for
receiving the lower end of a relatively rigid elongated blade
aligning leaf or knife 24 on which a stack of razor blades 26 is
positioned. A clamping structure 28 at the upper end of knife 24
secured a stack of blades 26 in position on the knife and in turn
is secured to an upper aligning ring 30. An electrical connection
to the blade stacks 26 is made via conductor 32 and feed through
connection 34 in the base 12. Drive shaft 36 is coupled to ring
assembly 16 to rotate the blade stacks 26 via chain 38. In a
typical processing run of double edged blades in this apparatus,
each stack is twelve inches long and contains three thousand blades
while in a typical processing run of single edge injector blades,
each stack contains twelve hundred blades. The sharpened edges of
the blades are 63/4 inches from the axis of chamber 10. Other
support structures, such as those for coils of blade strip of the
type disclosed in co-pending application Ser. No. 693,529, filed
Dec. 26, 1967 and now abandoned, may be substituted for these
support structures.
Also mounted within the chamber coaxially with the chamber axis is
a target rod 40 that in a particular embodiment includes platinum
and chromium. Rod 40 is suspended from chamber top plate 42 by
insulator structure 44. A water cooled dark space shield 46, also
suspended from top plate 42, is provided to protect insulator 44.
The exposed length of target rod 40 below shield 46 is 29 inches
and that exposed length is positioned symmetrically with respect to
the stacks of razor blades 26. In these embodiments the rod 40 is
11/4 inches in diameter and has a wall thickness of one-fourth
inch. Coolant from a suitable source 48 is circulated through rod
40 for cooling purposes. Connected to the target rod 40 is a
matching network 50 that includes fixed capacitor 52, inductor 54
(adjustable over the range 0-5 microhenrys) and capacitor 56
(adjustable over the range 0-1,000 picofarads), the matching
network being connected to an RF (13.56 mHz) voltage supply 60 via
shielded conductor 62.
A stainless steel wire mesh cylinder 66, 31/4 inch in diameter with
one-eighth inch apertures, is suspended from dark space shield 46
by flange 68 that is solidly bolted to shield 46. A stainless steel
plate 70 is secured at the lower end of mesh cylinder 66. Two
Helmholtz coils diagrammatically indicated at 72 surround chamber
10, one above and one below the blade stacks. These coils, when
energized, create a vertical magnetic field of about 100 gauss
magnitude in the chamber 10. The use of mesh cylinder 66 and the
magnetic field increases the metal deposition rate and reduces
secondary electron bombardment of the blades.
The target 40 may take a variety of forms. In one form the target
may be a sintered compact of platinum and chromium. In a second
form as indicated in FIG. 1, the target 40 is formed of alternating
exposed sections of chromium 74, and platinum 76. In one
embodiment, strips of platinum ribbon, each strip being 0.002 inch
thick, 1/2 inch wide and 4 inches long, are disposed in annular
grooves in a chromium rod to form rings 76 which are spot welded to
the rod. The rings 76 are equally spaced from one another and in
the illustrated embodiment, the exposed surface area of this target
assembly is 19 percent platinum and 81 percent chromium.
In operation of this apparatus, the sharpened blades 26 in stacks,
are placed in the chamber on knives 24. The chamber is evacuated
and argon at a pressure in the range of 10 microns is placed in the
chamber. The blades are then energized with a DC potential applied
through connection 34 (the chamber being grounded) and cleaned by
glow discharge for 5 minutes. After cleaning, the chamber is
evacuated and argon at pressure of 5-8 microns is placed in the
chamber. With the blade stacks and chamber grounded, a potential is
applied from power supply 60 to target 40. Argon ions are produced
which bombard target 40 and release atoms of the two metals. The
released atoms are deposited on exposed surfaces, including the
sharpened blade edges. This operation with an elongated target rod
and plural blade stacks forms an easily controlled
platinum-chromium alloy coating uniformly on the blade edges to
thicknesses of less than 600A. The alloy composition is a direct
function of the exposed surfaces of the metals in the target rod.
Thus, with the specific target rod configuration shown in FIG. 1 an
alloy composition close to the platinum-chromium compound Cr.sub.3
Pt is deposited, the alloy having about 55 weight percent (24
atomic percent) platinum. Deposition rates are a function of
applied power. For example, an input power of two kilowatts
provides a deposition rate of 50A/ minute while an input power of
five kilowatts provides a deposition rate of 150A/ minute.
The graph of FIG. 3 shows micro hardness (using a Vickers diamond
needle with a two hundred gram load and converted to DPHN) of
platinum-chromium alloys of differing compositions deposited by
sputtering on a planar substrate to a thickness of 0.0015 inch in
accordance with the invention, the graph being a plot of hardness
as a function of the platinum content of the sputtered alloy. The
hardness of the alloys in the vicinity of the intermetallic
compound Cr.sub.3 Pt (25 atomic percent platinum), which compound
has the A15 cubic crystalline structure, remains stable and is
substantially independent of heat treatment up to 1,200.degree. C.
The 50 atomic percent chromium-platinum alloy is disordered as
sputtered in a thin film but undergoes ordering on heating with a
significant increase in strength, the hardness peak at about 50
atomic percent platinum being due to the heating to which the
material was subjected during the sputtering of the layer to a
thickness of 0.0015 inch.
As a specific example, sixty thousand stainless steel razor blades
having the following composition:
carbon .54 - .62% chromium 13.5 - 14.5% manganese .20 - .50%
silicon .20 - .50% phosphorus, max. .025% sulphur, max. .020%
nickel, max. .50% max. iron remainder
were sharpened to an included solid angle of 24.8.degree. and
placed on 18 knives 24.
The pressure in the chamber was reduced to 0.1 micron and a
discharge sustaining atmosphere of argon was then bled into the
chamber to increase the pressure to 10 microns. A direct current
glow discharge was initiated in this argon atmosphere at a voltage
of 1,600 volts and a current of 1,100 milliamperes and maintained
for 5 minutes. The blade stacks 24 were then connected to ground
and 4 kilowatts of RF power (at a frequency of 13.56 megacycles and
at a DC negative bias of about 900 volts with a superimposed RF
signal of about 1,000 volts peak to peak) was applied to rod 40
with the matching network adjusted for zero reflected power for 4
minutes. The RF power was applied 10 seconds before application of
the DC power was entirely terminated and was increased gradually to
4 kilowatts as the DC power was being reduced. The Helmholtz coils
72 were energized at the same time that the RF power was initially
applied. After the end of the four minute sputtering interval the
blade stacks were turned and the above described cleaning and
sputtering steps were repeated. The resulting platinum-chromium
alloy coating had a hardness of about 960 DPHN and a thickness of
about 350A and extended along the entire cutting edge of the blades
and back along the final facet for a length of at least 0.001 inch.
A coating of polytetrafluoroethylene telomer was then applied to
the edges of the blades in accordance with the teaching in
copending application Ser. No. 384,805, filed July 23, 1964 in the
name of Irwin W. Fischbein now U.S. Pat. No. 3,518,110. This
processing involved heating the blades in an argon environment to a
temperature preferably in the range of 590.degree.-806.degree. F
and provided on the cutting edges of the razor blades an adherent
coating of solid fluorocarbon polymer. After heating the equivalent
hardness of the edge metal (the composite of the thin alloy film
and the underlying blade metal) was 700 DPHN. These blades
exhibited excellent shaving properties and long shaving life.
As a second example, a pure chromium disc 6 inches in diameter and
one-fourth inch thick had spot welded to its surface squares of
pure platinum foil 1 cm. on a side and 0.002 inch thick. These foil
squares were spaced on the surface so that 27 percent of the
chromium surface was covered with platinum. A 41/2 inch stack of
stainless steel blades were placed on a 5 inch diameter aluminum
disc in an RF sputtering unit. (This apparatus may also be used for
processing a coiled stack of blade strip with the strip placed on
the aluminum disc so that the sharpened edges of the strip are
aligned with one another and define an exposure axis or plane.) The
platinum-chromium disc surface was disposed parallel to the blade
edges at a distance of 21/2 inches. The RF power could be fed to
the plate supporting the blades or to the platinum-chromium plate
above the blade stack. The pressure in the vacuum chamber was
reduced to 0.1 micron of mercury and then pure argon gas was bled
into the chamber to a pressure of ten microns of mercury. The
aluminum disc and blades were then cleaned for 2 minutes with 0.2
KW of RF power (at 13.56 megacycles with a DC negative bias of
about 2,500 volts and a superimposed RF signal of about 3,300 volts
peak to peak). The platinum-chromium target was covered by a metal
shield during this cleaning step. The shield was then placed so
that the blades were shielded and the platinum-chromium target
plate was cleaned with an applied power of 0.4 KW (at 13.56
megacycles with a DC negative bias of about 3,400 volts and a
superimposed RF signal of about 4,500 volts peak to peak), for 1
minute, while maintaining 10 microns of mercury pressure of argon
gas. The shield was then removed from between the blades and the
platinum-chromium target. Sputtering (ion bombardment) of the
target now proceeded at 0.4 kilowatts for 1 minute and 40 seconds.
The edges of the blades facing the target received a
platinum-chromium alloy coating consisting of 58 weight percent
platinum and 42 weight percent chromium to a thickness of about
250A and a hardness of about 800 DPHN. These blades, when coated
with a thin film of a PTFE telomer in the same manner as in the
previous example exhibited excellent shaving properties.
As a third example, a titanium disc one-eighth inch thick and 3
inches in diameter (appropriate dark space shielding producing an
effective disc diameter of 25/8 inches) had spot welded to its
surface squares of pure platinum foil one-half cm. on a side and
0.010 inch thick. These foil squares were placed on the surface of
the disc so that 8 percent of the titanium surface was covered with
platinum. A stack of one hundred stainless steel blades was placed
on a water cooled five inch diameter aluminum disc in an RF
sputtering unit. The platinum-titanium disc surface was disposed
parallel to the blade edges at a distance of 21/2 inches. A shutter
was interposed midway between the blades and the platinum-titanium
disc. An environment of argon gas at a pressure of 10 microns of
mercury was placed in the vacuum chamber. The aluminum disc and
blades were than cleaned for 2 minutes at 0.2 kilowatts of RF power
at 13.56 mHz (with a DC negative bias of about 2,500 volts and a
superimposed RF signal of about 3,300 volts peak to peak), during
which interval the platinum-titanium target was shielded by the
shutter. The target was then presputtered with an applied power of
0.8 kilowatts (at 13.56 megacycles with a DC negative bias of about
4,200 volts and a superimposed RF signal of about 5,000 volts peak
to peak) for ten minutes while maintaining the pressure of the
argon gas in the chamber at 10 microns of mercury. The shutter was
then removed from between the blades and platinum-titanium target
and a platinum-titanium alloy was deposited on the blade edges by
sputtering at 0.8 kilowatts applied power for 2 minutes. The
coating was a platinum-titanium alloy consisting of 24 atomic
percent platinum and seventy-six atomic percent titanium and had a
thickness of about 350A and was harder than the underlying blade
metal. These blades, when coated with a suitable interfacial
bonding layer and a thin film of PTFE telomer exhibited excellent
shaving properties and long shaving life.
As a fourth example, employing a similar group of blades six
tungsten coils plated with palladium were mounted in a chamber of
the type disclosed in co-pending application Ser. No. 693,529,
filed Dec. 26, 1967 and now abandoned. With argon in the chamber at
a pressure of 10 microns, a glow discharge was initiated at a
voltage of 1,600 volts and a current flow of 975 milliamperes for 7
minutes. The argon flow was then terminated and the pressure in the
chamber reduced to 0.1 micron. The tungsten-palladium coils were
then energized with an electrical potential of 12 volts and an
electric current of 200 amperes for 15 minutes to vaporize both
palladium and tungsten and deposit on the blades a
palladium-tungsten alloy that contained about 50 percent palladium
and 50 percent tungsten by weight. The coated edges had an
equivalent hardness of 690 DPHN and after application of the
fluorocarbon telomer as in the other examples the equivalent
hardness of the edge metal was 650 DPHN. The blades exhibited
excellent shaving properties.
In a fifth example, a brass target 6 inches in diameter was osmium
plated. Chromium was then sputtered onto the target through a mask
so that 10 square inches of osmium appropriately spaced to provide
uniform deposition of osmium was left exposed. This osmium-chromium
target was used in the same apparatus as used in the second
example. The aluminum disc and blades were cleaned for 2 minutes
with an RF power of 0.2 kilowatts; the osmium-chromium target was
then presputtered for 1 minute at an applied RF power of 0.4
kilowatts; and then sputter deposition proceeded for 2 minutes at
an RF power of 0.4 kilowatts. The edges of the blades facing the
target received an osmium-chromium alloy coating consisting of 32
atomic percent osmium and 68 atomic percent chromium to a thickness
of 250 Angstroms. The blades were then coated with a thin film of
PTFE telomer and exhibited excellent shaving properties.
Other examples of the invention utilizing the same equipment as in
the second example are summarized in the following table:
ALLOY TARGET PROCESSING FILM COMPOSITION Cleaning Presputtering
Sputtering Thickness Composition Hardness (A)
__________________________________________________________________________
Iridium Chromium 71.7% Chromium RF RF RF 250 69% Chromium 1700
28.3% Iridium 0.2 Kw 7 mins. 75 secs. 31% Iridium 2 mins. 0.4 Kw
0.4 Kw Platinum Tungsten* 91% Tungsten RF RF RF 250 84% Tungsten 9%
Platinum 0.2 kw 3 mins. 100 secs. 16% Platinum 2 mins. 0.4 kw 0.4
Kw Iridium Platinum 79% Iridium RF RF RF 320 75% Iridium 1300 21%
Platinum 0.2 Kw 5 mins. 75 secs. 25% Platinum 2 mins. 0.4 Kw 0.4 Kw
Iridium Vanadium* 84.8% Vanadium DC RF RF 200 V.sub.3 Ir 1300 15.2%
Iridium 2000 volts 6 mins. 120 secs. 25 ma 0.4 Kw 0.4 Kw 7 mins.
Iridium Tantalum* 86% Tantalum RF RF RF 240 Ta.sub.3 Ir 1450 14%
Iridium 0.2 Kw 8 mins. 120 secs. 2 mins. 0.4 Kw 0.4 Kw Ruthenium
Chromium 71% Chromium DC RF RF 250 71% Chromium 1200 29% Ruthenium
2000 volts 5 mins. 100 secs. 29% Ruthenium 25 ma 0.4 Kw 0.4 Kw 7
mins.
__________________________________________________________________________
The alloys indicated by an asterisk exhibited inferior adhesion
compatibility with the PTFE telomer. Satisfactory adhesion was
achieved by depositing an interfacial layer of Cr.sub.3 Pt on those
alloys. After sputter deposition of the alloy, a chromium disc with
platinum squares spot welded to it was substituted for the target
in the deposition chamber. The blades with the alloy film were
cleaned for 30 seconds at 0.2 KW RF power; the substituted target
was presputtered for 10 seconds at 0.4 KW RF power; and then the
Cr.sub.3 Pt alloy was sputter deposited for thirty seconds at 0.4
KW RF power, forming a 75 A interfacial bonding layer for the PTFE
telomer, the blades so treated exhibited excellent shaving
properties and long shaving life.
While particular embodiments of the invention have been shown and
described, various modifications thereof will be apparent to those
skilled in the art and therefore it is not intended that the
invention be limited to the disclosed embodiment or to details
thereof and departures may be made therefrom within the spirit and
scope of the invention.
* * * * *