IL34931A - Metal articles with protective metal layers and methods and apparatus for their manufacture - Google Patents

Description

snv***'? o'apnni nia»¾?i Metal articles' with protective metal layers and methods and apparatue for their manufacture' THE GILLETTE COMPANY 0.33195 CASE 7039 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 6000A and preferably less than 2500A. 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 aa they tend to break away from the underlying shaving edge under the abrasion forces en-countered in shaving, such tendency rendering the blades commercially unsatisfactory0 Further, a shave facilitating polymeric fluorocarbon coating is frequently cured on the blade edges by exposing the blades to elevated temperatures, β·β·» 550°P. to 800°P. 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 fluoro-carbon 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, palladium, platinum, 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 Al5 cubic structure or the tetragonal ordered (sigma phase) structure and alloy compositions within about ±5 weight per cent of these compounds, those alloys having excellent heat stability.

In the case of platinum-chromium alloys, a preferred range of platinum content is 15- 5 atomic per cent and where the environment of use is particularly corrosive it is preferred that the platinum content be at least 21 atomic per cent.

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 per cent has a dissolution rate in boiling hydrochloric acid of 0.008 mils per minute, which may be contrasted with a dissolution rate of 1000 mils per minute for pure chromium in boiling hydrochloric acid. In typical applications, the alloy film in accordance with the invention ia 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^N compound is particularly advantageous as it has greater heat stability than the underlying steel. For example, the hardness of a Cr^Pt alloy film on a razor blade in accordance with the invention is substantially independent of heat treatment temperatures up to 1200°Co In such a platinum-chromium alloy film, a preferred range of platinum content of the film is 15-30 atomic per cent and particularly advantageous results are obtained with a film having a platinum content of 21-27 atomic per cent. The alloy film in accordance with the invention is at least as hard as the underlying blade metal o and should not exceed 600A in thickness, a preferable range being 50-500A and the best results being obtained with a o thickness in the range of lOO-l+OOA. Further, where a fluoro-carbon shave facilitating coating is utilized, alloy films that employ either chromium or ah N class metal as the strengthening metal provide most satisfactory coating adherenceβ 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 7i>A or less) overlayer of the Cr^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 metallurgically separate form from the N metal. The source may take various forma, 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 include the following: COMPOSITION IN % c Cr Mo Si Ni 1.25 .2 .2 — 1.00 6.0 1 — .96 13.9 .3 .65 10.5 1.0 .3 .58 11+. o .3 — .i+o 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 1700 DPHN), remain harder than prior art commercial blades after the blades are subjected to polymer curing temperatures in the range of 550-800°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.

Pig. 1 is a sectional view of a form of apparatus employed in the practice of the invention! Pig. 2 is a sectional view of the apparatus shown in Pig. 1, taken along the line 2-2 of Pig. lj and Pig. 3 is a graph indicating characteristics of an alloy in accordance with the invention.

The sputtering (ion bombardment) apparatus shown in Fig. 1 includes a stainless steel cylindrical chamber 10 eighteen inches in diameter and thirty-two inches high mounted on base 12. Base 12 is coupled through port 11+ to a suitable vacuum system (not shown ). A butterfly valve that has an aperture one inch in diameter is disposed downstream of port lk and may be moved to closed position during sputtering to reduce back streaming of the diffusion pump0 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 2k on which a stack of razor blades 26 is positioned,, A clamping structure 28 at the upper end of knife 2k secures a stack of blades 26 in position on the knife and in turn is secured to an upper aligning ring 30. An elec-trical connection to the blade stacks 26 is made via conductor 32 and fed through connection 3k in tne 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 9 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 6-3/k inches from the axis of chamber 10.

Other support structures, such as those for coils of blade s .t.ri _■p of* ^the .t_ype disc ·l,osed÷ in B::cr¾^i^ti«sKht¾ agt==e8n^tp¾Nio^.^I.2n1=5. O55 (#-Τ&Τ"&Έ¾-.--693,£29 "»€teeeHS&W- may be substituted for these support structures.

Also mounted within the chamber coaxially with the chamber axis is a target rod kO that in a particular embodi-ment includes platinum and chromium. Rod kO is suspended from chamber top plate I4.2 by Insulator structure lj.l . A water cooled dark space shield I .6, also suspended from top plate J4.2, is provided to protect insulator -4l-« The exposed length of target rod 1+0 below shield 1+6 is twenty-nine inches and that exposed length is positioned symmetrically with respect to the stacks of razor blades 26. In these embodiments the rod 1+0 is 1-1/1+ inches in diameter and has a wall thickness of 1/1+ inche Coolant from a suitable source 1+8 is circulated through rod 1+0 for cooling purposes . Connected to the target rod I .0 is a matching network $0 that includes fixed capacitor 2, inductor 51+ ( adjustable over the range 0-5 microhenrys ) and capacitor 6 ( adjustable over the range 0-1000 picofarads ) , the matching network being connected to an RP ( 13. 6 mHz ) voltage supply 60 via shielded conductor 62.

A stainless steel wire mesh cylinder 66, 3-1/1+ inch in diameter with 1/8 inch apertures , is suspended from dark space shield 1+6 by flange 68 that is solidly bolted to shield 1+6. A stainless steel plate 70 is secured at the lower end of mesh cylinder 66. Two Helmholtz coils dia-grammatically indicated at 7 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 depos ition . rate and reduces secondary electron bombardment of the blades .

The target 1+0 may take a variety of forms . In one form the target may be a sintered c ompact of platinum and chromium. In a second form as indicated in Pig. 1, the target 1+0 is formed of alternat ing exposed sections of chromium lb,, and platinum 76. In one embodiment, strips of platinum ribbon, each strip being 0.002 inch thick, 1/2 inch wide and four 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$ platinum and 81$ chromium.

In operation of this apparatus, the sharpened blades 26 in stacks, are placed in the chamber on knives 2I4.. 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 (the chamber being grounded) and cleaned by glow discharge for five minutes. After cleaning, the chamber is evacuated and argon at pressure of -8 microns is placed in the chamber. With the blade stacks and chamber grounded, a potential is applied from power supply 60 to target I.0. Argon ions are produced which bombard target i+O 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 with proportions close to the platinum-chromium compound (2I. atomic per cent) platinum. Deposition rates are a function of applied power. For example, an input power of O two kilowatts provides a deposition rate of 50A/minute while an input power of five kilowatts provides a deposi- o tion rate of 15OA/minute.

The graph of Pig. 3 shows micro hardness (using a Vickers diamond needle with a two hundred gram load and converted to DPHN - Diamond Pyramid Hardness Number )„ 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^Pt (twenty-five atomic per cent platinum), which compound has the Al5 cubic crystalline structure, remains stable and is substantially independent of heat treatment up to 1200°C. The fifty atomic per cent 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 per cent 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 ,$k - .62% chromium manganese silicon phosphorus, max. sulphur, max. were sharpened to an included solid angle of 21+.8° and placed on eighteen aligning knives 2I..

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 ten microns o A direct current glow discharge was initiated in this argon atmosphere at a voltage of 1600 volts and a current of 1100 milliamperes and maintained for five minutes. The blade stacks 26 were then connected to ground and four kilowatts of RP power (at a frequency of 13<>56 megacycles and at a DC negative bias of about 900 volts with a superimposed RP signal of about 1000 volts peak to peak) was applied to rod I4.0 with the matching network adjusted for zero reflected power for four minutes «, The RP power was applied ten seconds before application of the DC power was entirely terminated and was increased gradually to four kilowtt as;i,he . DCv.power was being reduced,, The Helmholtz coils 72 were energized at the same time that the RP 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 o about 96Ο 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 freieieea* was then applied to the edges of the blades in accordance with the teaching Israel Patent No. 23963 . This processing involved heating in the range of 590-806°F. and provided on the cutting edges of the razor blades an adherent coating of solid fluorocarbon polymer. After heating the micro hardness of the edge metal (the composite of the thin alloy film and the underlying blade metal) was equivalent to 700 DPHNe These blades exhibited excellent shaving properties and long shaving life.

As a second example, a pure chromium disc six inches in diameter and I/I. inch thick had spot welded to its surface squares of pure platinum foil 1 cm. on a side and 0.002 inch thicko These foil squares were spaced on the surface so that 27$ of the chromium surface was covered with platinum,, A i-l/2 inch stack of stainless steel blades was placed on a five inch diameter aluminum disc in an RP 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 2-1/2 inches « The RP power could be fed to the plate supporting the blades or to the platinum-chromium plate above the blade stack. The pressure in the vacuvim chamber was reduced to 0o l 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 two minutes with 0.2 KW of RP power (at 13.56 megacycles with a DC negative bias of about 2500 volts and a superimposed RP signal of about 3300 volts peak to peak). The platinum- cleaning step. The blades were shielded and the platinum-chromium target plate was cleaned with an applied power of 0,1+ KW (at 13.56 megacycles with a DC negative bias of about 31+00 volts and a superimposed RP signal of about 1+500 volts peak to peak), for one minute, while maintaining ten 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.I. kilowatts for one minute and forty seconds. The edges of the blades facing the target received a platinum-chromium alloy coating consisting of 58 weight per cent platinum and 1+2 weight per cent chromium to a thickness of about 25OA and a hardness of about 800 DPHN. These blades, when coated with a thin film of a PTPE telomer in the same manner as in the previous example exhibited excellent shaving properties.

As a third example, a titanium disc 1/8 inch thick and three inches in diameter (appropriate dark space shielding producing an effective disc diameter of 2-5/8 inches ) had spot welded to its surface squares of pure platinum foil 1/2 cm. on a side and 0.010 inch thick. These foil squares were placed on the surface of the disc so that Q 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 RP sputtering unit. The platinum-titanium disc surface was disposed parallel to the blade edges at a distance of 2-1/2 inches A shutter was interposed midway between the blades - at a pressure of 10 microns of mercury was placed in the vacuum chamber. The aluminum disc and blades were then cleaned for two minutes at 0.2 kilowatts of RP power at 13.£6 mHz (with a DC negative bias of about 2500 volts and a superimposed RP signal of about 3300 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 I4.2OO volts and a super— imposed RP signal of about 5000 volts peak to peak) for ten minutes while maintaining the pressure of the argon gas in the chamber at ten 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 two minutes. The coating was a platinum-titanium alloy consisting of twenty-four atomic per cent platinum and seventy-six atomic per cent titanium and had a thickness o of about 350A and was harder than the underlying blade metal. These blades, when coated with a suitable inter-facial bonding layer and a thin film of PTPE 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 oo- ponding With argon in the chamber at a pressure of 10 microns, a glow discharge was initiated at a voltage of 1600 volts and a current flow of 975 milliamperes for seven 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 twelve volts and an electric current of 200 amperes for fifteen minutes to vaporize both palladium and tungsten and deposit on the blades a palladium-tungsten alloy that contained about $0 palladium and Oo 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 six inches in diameter was osmium plated. Chromium was then sputtered onto the target through a mask so that ten square inches of osmium appropriately spaced to provide uniform deposition of osmium was left exposed. This osmium-chromium,i.target. Was used; inuthe same .apparatus. as, us.ed.ji nt e..second,example. The aluminum disc: and blades were cleaned for two minutes with an RP power of 0o2 kilowatts ? the osmium-chromium target was then presputtered for one minute at an applied RP power of 0 o - kilowatts j and then sputter deposition proceeded for two minutes at an RP power of 0.I4. kilowatts. The edges of the blades facing the target received an osmium-chromium alloy coating consisting of 32 atomic per cent osmium and 68 atomic per cent chromium to a thickness of 2f?0 Angstroms. The blades were then coated with a thin film of PTPE 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 : TARGET PROCESSING ALLOY COMPOSITION Cleaning Presputtering Sputtering Iridium Chromium 71,7% Chromium RF RF RF 28.3# Iridium 0.2 Kw 7 mins. 75 sees. 2 mins. O.U Kw O.U Kw Platinum Tungsten* 91% Tungsten RF RF RF 9% Platinum 0.2 Kw 3 mins. 100 sees. 2 mins. O.U Kw O.U Kw Iridium Platinum 79% Iridium RF RF RF 21$ Platinum 0.2 Kw 5 mins. 75 sees. 2 mins. O.U Kw O.U Kw Iridium Vanadium* Qk.8% Vanadium DC RF RF l5.2g Iridium 2000 volts 6 mins. 120 sees. ma O.U Kw O.U Kw 7 mins.

Iridium Tantalum* 86% Tantalum RF RF RF 11$ Iridium 0.2 Kw 8 mins. 120 sees. 2 mins. O.U Kw O.U Kw Ruthenium Chromium 71% Chromium 29% Ruthenium 2 7 mins.

The alloys indicated by an asterisk exhibited inferior adhesion compatibility with the PTPE telomer.

Satisfactory adhesion was achieved by depositing an inter-facial layer of Cr-jPt 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 thirty seconds at 0.2 KW RP power; the substituted target was presputtered for ten seconds at O.I. KW RP power; and then the Cr^Pt alloy was sputter deposited for thirty seconds at 0,i KW RF power, forming a o 7 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 c

Claims (3)

34931/2 CASE 7039 CLAIMS . , . ... ■ -. -

1. A" me l article,, such as a razor blade , ' having on a surface thereof a film of an 'alloy of (a) iridium, osmium, palladium, platinum:, rhenium, rhodium, or ruthenium (herein termed an N metal )' arid (b) chromium, manganese, molybdenum, niobium, tantalum, titanium, tungsten, vanadium or an N metal different from the other N metal of the alloy (herein termed a strengthening metal).. , . 2, An article, according to claim 1, in which the N metal of the alloy' is iridium, osmium, platinum,., rhodium, or••ruthenium. · 5 3o An article according to claim 1 or 2, in which the strengthening metal of the- alloy is chromium, titanium or the different N metal, chromium being preferred, * An article' according to claims 2 and 3, in which the alloy is composed of (a) platinum, iridium or osmium and (b ) chromium. 5. An article according to any. one of the preceding claims, in which the corrosion resistance of the alloy film is such that the surface of the article (e.g. the cutting edge of a razor blade) shows no sign of corrosion after immersion in concentrated hydrochloric acid for one minute * 6. An article according to any one of the preceding claims, in which the alloy film ds at least as hard as the underlying met l 0 7. An article accordin to an one of the recedin *49*1 ¾ claims, in which the alloy is an intermetallic compound with either the ordered Al5 cubic structure or the tetragonal ordered (sigma phase) structure or a composition with proportions within t£ weight per cent of such a compound, 8 , An article according to any one of the preceding claims, in which the alloy is composed of platinum and chromium. 9 , An article according to any one of claims 1 to 7 , in which the alloy is composed of platinum and titanium. 10, An article according to any one of the preceding claims, in which the alloy has a maximum grain (crystallite) o size of less than 1000A. 11, An article according to any one of the preceding claims, in which the alloy film has a. thickness of at least o . . . - 50A , , . . 12, An article according to any one of the preceding claims, in which the alloy film has a thickness of less than 600A and preferably in the range of 100-i00A, 13· An article according to any one of the preceding claims, which is a razor blade and includes a fluorocarbon polymer shave-facilitating coating on the alloy film, ll\. o An article according to claim 8 , in which the alloy is composed of 1 -6 (preferably 21-65 ) atomic per cent platinum and the remainder chromium, 15. An article according to claim II ., in which the alloy is composed of 15-30 (preferably 21-27 ) atomic per cent platinum and the remainder chromium, 16 , An article according to any one of the preceding claims, in which the alloy film has a micro hardness in excess of 750 DPUN, 9 9*1 / ' 17. A method of making an article, such as a razor blade, according to any one of the preceding claims, which comprises depositing a thin film of the alloy on the underlying metal of the article (substrate) while maintaining the article in a reduced pressure environment by subjecting a target having components consisting of the metal and strengthening metal to an ion bombardment for transferring atoms of said metals, from the target to the substrate to form the alloy film. 18. A method according to claim 17» including the step of electrically cleaning the surface of the article in the reduced pressure environment prior to depositing the alloy film. 19. A method according to claim 17 or l8 , in which the article is a razor blade, and including the further step of applying a shave-facilitating coating (e.g. of a fluorocarbon polymer) on the alloy film. 20. A method according to claim 19, in which a fluorocarbon polymer is sintered on the alloy film at a temperature in the range of 550-800°F. 21. A method according to any one of claims 17 to 20, for processing razor blades, which comprises positioning the razor blades in a plurality, of stacks with the bodies of the blades in each stack in contact with one another and the sharpened edges of the blades aligned with one another, subjecting said stacks to a cleaning operation in a reduced pressure environment to remove contamination from the sharpened edges of the blades, subjecting a target rod disposed equidistantly from the stacks to an ion bombardment to transfer material from the rod to deposit a thin film on the 34931/2 cleaned sharpened edges of the blades, and applying a shave-facilitating coating on the deposited film0 22. A method according to claim 21, in which the stacks are disposed in a circle about the target rod. 23 o Apparatus for carrying out the method of any one of claims 17 to 22, which comprises a chamber adapted to provide an environment of reduced pressure, means for supporting a stack of razor blades within said chamber with the bodies of the blades in face to face contact and the sharpened edges of the blades in alignment, a target parallel to the axis of the stack and an electrical circuit for generating ions to bombard said target for transferring material therefrom to the blade edges, 21+. , Apparatus according to claim 23, including means for separating the target into two elongated sections «,

2. „ Apparatus according to claim 21+, in which the target-separating means comprises a shield located between the target and the blade stack and of less length than the blade stack. 26. Apparatus according to claim 2 » in which the shield is supported by an electrically conductive perforate cylinder surrounding the target. 27. Apparatus according to any one of claims 23 to 26, in which the target is an elongated cylindrical member and a plurality of stacks of razor blades are spaced equidistantly therefrom0 28. Apparatus according to any one of claims 23 to 27, in which the axial extent of the stack of blades is less than the length of the target. 29. Apparatus according to any one of claims 23 to 28, 34931/2 strengthening metal and discrete equally spaced elements of the N metal secured to said base portion,, 30. A target element for use in a method according to any one of claims 17 to 22s the surface of which for exposure to the ion bombardment consists solely of the N metal and strengthening metal in proportions to provide the desired proportions of these metals in the alloy. 31. A target element according to claim 30, in which the strengthening metal forms a base segment and a plurality of segments of the N metal are secured in bonded relation to the base segment . 32. A target element according to claim 30 or 31»-in the form of an elongated rod the exposed surface of which is composed of alternating bands of the N metal and strengthening metal0 33 o The article such as a razor blade substantially as hereinbefore described and as set forth in the Examples „ 3k-· The method of making an article such as a razor blade substantially as hereinbefore described and as set forth in the Examples „ 35· The apparatus for making an article such as a razor blade substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2 of the accompanying drawings 0

3. 0 An article such as a razor blade whenever made by a method according to any one of the preceding method claims. 37 o The target element substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. - as - For the Applicants