Patent Publication Number: US-7587829-B2

Title: Ceramic blade and production method therefor

Description:
RELATED APPLICATIONS 
   The present application is a continuation of and claims the benefit of U.S. patent application Ser. No. 10/475,283 filed Apr. 16, 2004 entitled CERAMIC BLADE AND PRODUCTION METHOD THEREFOR”, now U.S. Pat. No. 7,140,113. Application Ser. No. 10/475,283 is a 371 of PCT Application No. PCT/US02/12380, filed Apr. 17, 2002, which claims benefit of Provisional Patent Application 60/284,405 filed Apr. 17, 2001. 

   FIELD OF THE INVENTION 
   The present invention generally relates to cutting tools of the type that have a single or a plurality of cutting edges. In particular, the present invention is directed to a ceramic cutting tool having an extremely fine cutting edge. One such blade is a shaving razor blade. The invention also relates to a method for producing a ultra-fine cutting edge on a ceramic material which edge is also extremely durable over time and use. 
   BACKGROUND OF THE INVENTION 
   Since human kind first began to employ tools, one of the most versatile and prolific tools has been the knife. Primitive humans used knives for piercing, cutting and scrapping. Here, knives were first formed of a stone material, such as quartz, flint or obsidian. The knife edge was created by pressure-flaking the stone along its crystalline cleavage planes with intersecting planes creating the cutting edge. While such technique resulted in extremely sharp edge, stone knives were brittle such that the edge was easily broken or chipped. 
   As technological advancement occurred, knives or other cutting blades began to be formed out of metal. Metal was less brittle and more malleable than stone. Thus, metal blades with cutting edges had the advantage of resistance to chipping. However, the cutting edges of metal blades were often not as sharp as stone edges and would tend to become dull with time and use unless resharpened. However, as technology developed into more modern times, the sharpness of metal edges began to approach the sharpness of stone edges; however, dulling remained a problem. 
   Recent developments in materials science, however, has resulted in high technology ceramic materials which, like their stone cousins, can form a matrix onto which an extremely sharp blade edge may be formed. Ceramic blade edges, however, still are subject to some chipping due to their brittleness. Materials traditionally used for forming ceramic blades include alumina and zirconia. Usually, a blade blank is formed by mixing a ceramic powder with a binder or plastisizer and compressing the mass under high pressure to create a solid cohesive mass. Typical particle sizes for such materials are on the order of 0.5 microns or less. The compressed material is typically fired in a furnace until it is hardened into a cured state. The cutting edge is formed on the material either before or after this hardening step. 
   In any event, ceramic cutting blades have many advantages over their metal counterparts. In addition to their extremely sharp edge, ceramic cutting blades can be readily sterilized, for example, when these blades are used as medical scalpels. Where employed in industrial applications, such as the semi-conductor industry, there is less risk of contamination from the ceramic material since it is rather benign to the semiconductor doping process. Metal, on the other hand, can contaminate and ruin the semi-conductor materials. 
   There have been some attempts to advance the art of ceramic blades in recent years. One such example is shown in U.S. Pat. No. 5,077,901 issued Jan. 7, 1992 to Warner et al. In this patent, a ceramic blade and production methodology is described. The blade includes a cutting edge formed by first and second cutting faces oriented at a bevel angle. At least one of the cutting faces includes striations having a grain direction substantially perpendicular to the cutting edge with these striations having a width of between 20 and 40 microns. These striations have benefits including increase blade endurance. Further, micro-chipping of the material is described as causing the material between adjacent striations to slough in a direction perpendicular to the edge. The “pressure flaking” during use tends to increase the sharpness of the cutting edge as opposed to diminishing the sharpness. 
   Despite the advantages achieved by the ceramic blades in the &#39;901 Patent, there remains a need for increasingly improved ceramic cutting blades. There is a need for ceramic blades that can be used in medical and industrial applications as well as blades that may be used for consumer products, such as razor blades. There is a need for such ceramic blades that have increased sharpness and enhanced durability while at the same time can be produced by a methodology that is cost effective and within the economic reach of the ordinary, average consumer. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a new and useful ceramic blade having an enhanced cutting edge. 
   A further object of the present invention is to provide a method for manufacturing ceramic blades which produces a more durable edge while at the same time being cost efficient in implementation. 
   Still a further object of the present invention is to provide a ceramic blade with a cutting edge that resists chipping or particle dislodgment at the cutting edge margin so as to be highly durable over an extended period of use. 
   Still a further object of the present invention is to provide a ceramic blade and method of production that may be employed to create cutting edges of a variety of shapes. 
   Yet a further object of the present invention is to provide a shaving razor blade having an extended useful life. 
   According to the present invention, then, a blade comprises a ceramic body formed of a selected ceramic material that is a matrix of ceramic particles of a selected particle size. This ceramic body includes a cutting edge defined by at least two converging faces such that the margins of the two faces adjacent to the cutting edge define an edge portion. At least some of the ceramic particles located on the margin of one face which are adjacent to one another have contacting surfaces that are thermally fused together. In addition to or as an alternative to having the ceramic particles thermally fused to one another, a hard ceramic coating formed by a second ceramic material different from the first ceramic material may be formed on the margin of the cutting face adjacent to the cutting edge. The margin may have a width within a range of about 3.0 mm to about 5.0 mm. Moreover, it is desirable that a majority of the adjacent ceramic particles are the margin be fused to one another. 
   The cutting edge can be formed by two converging cutting faces. In this instance, it is desirable to treat margins of each of the faces adjacent to the cutting edge either by thermally fusing particles together of by providing the hard ceramic coating. In any event, the hard ceramic coating may be chromium nitride, zirconium nitride, titanium nitride, titanium carbon nitride or other coatings as known in the industry. 
   It is preferred that the ceramic body be formed of a sintered ceramic. The ceramic material may be selected from a group consisting of zirconia, alumina, tungsten carbide and the like. Moreover, these selected particle size is less than about .0.5 micron. 
   The converging faces may converge at a convergent angle of no more than 60°. Where the blade is to be used as a shaving razor blade, the ceramic body is formed as a plate having a thickness between about 0.1 inch (2.54 mm) and 0.25 inch (6.35 mm). Where a shaving razor blade is formed, the convergences angle is in a range between about 10° and 20° and, preferably, about 14.7°. 
   In a first method of forming a blade according to the present invention, a production blank is first formed out of a ceramic material. Here again, the ceramic material is formed as a matrix of ceramic particles of a selected particle size. An edge is then formed on the production blank. The method then includes the step of thermally fusing at least some of the ceramic particles that are in contact with one another in a margin of blade adjacent to the edge. 
   In this method, the production blank may be in the green state, and the step forming the edge is accomplished by green machining the production blank. The method then includes a further step of sintering the production blank. Alternatively, the production blank can be in a green state and is sintered and thereafter the edge is formed by grinding. 
   In any event, the step of joining the ceramic particles may be accomplished by scanning a margin portion that is adjacent to the edge with a laser beam at a selected wavelength for a selected width as measured from the edge. The selected wavelength may be in the ultra violet range and, according to the preferred embodiment, the selected wavelength is about 280 nm. Also, the margin portion is preferably about 3.5 microns in width and the laser beam has a diameter of the margin portion during the scanning step of about 1.0 microns. Further, the margin portion is scanned with the laser in a zigzag pattern at a rate of about 0.3 to 0.6 inches per second. In the first method, an additional step may be provided wherein a metal coating is deposited on the margin and thereafter the method includes the step of oxidizing the metal coating to produce a hard ceramic layer. 
   A second method according to the present invention includes the step of producing a production blank again out of ceramic material wherein the ceramic material is formed as a matrix of ceramic particles of a selected particle size. An edge is formed on the production blank. Thereafter, a metal coating is deposited on a margin of the production blank proximately to the edge and thereafter the metal coating is oxidize to produce a hard ceramic layer. 
   The second method of forming a blade contemplates forming the metal coating out of metal selected from a group consisting of chromium and zirconium. The step of oxidizing the metal coating is preferably accomplished by nitrating the metal coating. In this method, it is preferred that the hard ceramic layer be formed at a thickness of between about 0.7 and 1.0 nm. 
   These and other objects of the present invention will become more readily appreciated and understood from a consideration of the following detailed description of the exemplary embodiments of the present invention when taken together with the accompanying drawings, in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic view showing the processing steps of a streamlined method for producing a ceramic blade according to the present invention; 
       FIG. 2  is a diagrammatic cross-section showing the particles of a compressed ceramic blade edge according to the prior art; 
       FIG. 3  is an enlarged view of the distal cutting edge of a prior art ceramic blade; 
       FIG. 4  is a diagrammatic view, in magnified perspective, showing the distal cutting edge of a ceramic blade according to the present invention; 
       FIG. 5  is a block diagram showing the processing steps according to an expanded fabrication process of the present invention; 
       FIG. 6  is a top plan view showing a gross production blank according to the present invention; 
       FIG. 7  is a top plan view of the gross production blank shown in  FIG. 6  having a plurality of blade blanks removed therefrom; 
       FIG. 8  is a top plan view of the gross production blank of  FIGS. 6 and 7  showing additional production blanks removed therefrom; 
       FIG. 9  is a top plan view showing a razor blade according to the present invention; 
       FIGS. 10 through 18  depict the distal cutting edge of various blades implementing the methodology of the present invention; and 
       FIG. 19  is a perspective view of a shaving razor blade as an exemplary embodiment of ceramic blade and production method according to this present invention; 
       FIG. 20  is a side view in elevation showing the cutting face and cutting edge of the shaving razor blade of  FIG. 18 ; 
       FIG. 21  is a perspective view of a sintered production blank used to form the razor blade of  FIG. 18  illustrating the scanning pattern for the laser beam used to conduct such thermal fusing step; 
       FIG. 22  is a perspective view of a stacked array of a plurality of shaving razor blades in a holder used in the step of forming a hard ceramic coating according to the method of the present invention; 
       FIG. 23  is a cross sectional view taken about lines  23 - 23  of  FIG. 22 ; and 
       FIG. 24  is a diagrammatic view showing a vapor deposition chamber used to produce the hard ceramic coating for the blades and methods of the present invention. 
   

   DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
   The present invention is directed to a method of producing an improved blade edge on a ceramic blade blank or substrate. In addition, the present invention is directed to a ceramic blade having a cutting edge of specific described characteristics that can be produced, for example, by the method described herein. The blades according to the present invention enjoy a wide variety of potential applications including the industrial and medical uses as well as consumer applications. Of particular interest to this invention is a shaving razor blade. 
   A description of a simplified process according to the present invention is first presented. This is followed by a more detailed description of an expanded process as well as the discussion of the types of blades and cutting edges that may be created by the present invention. Finally, a shaving razor blade incorporating the features of the invention is described. 
   A. Streamlined Process 
   A streamlined process according to a first exemplary embodiment of the methodology of the present invention may be appreciated with reference to  FIG. 1 . As is shown in this Figure, six fundamental fabrications steps are contemplated. Each of these will be discussed in turn. 
   1. Ceramic Stock Formation 
   With reference to  FIG. 1 , it may be seen that the start of the process begins at reference number  10  and proceeds to a first step of ceramic stock formation at  12 . Ceramic stock formation involves the fabrication of the ceramic matrix out of which the blades according to the present method may ultimately be produced. Typically, this matrix is in the form of a raw ceramic sheet that is stiff yet pliable, in a manner not dissimilar from clay. Four primary techniques are known to produce the ceramic matrix which the blades may be formed. These include tape extrusion, dry pressing, slurry and roll compaction. 
   a. Tape Extrusion 
   According to the present invention, the preferred method for creating the raw ceramic matrix or sheet is referred to at tape extrusion. First, a selected mixture of ceramic powder is mixed with a binder or plastasizer to form a dough. While zirconia is the preferred ceramic material, it should be understood that other materials as is known in the art may be employed to form the ceramic dough. Examples of these materials include alumina and tungsten carbide. Suitable binders or plastisizers include acetone, MEK (methylketone) and the like, again as is known in the art. The components are placed in a tank and mixed to form a relatively homogenous damp mass that is similar in consistency to a dough-like clay. The mixed mass is taken from the tank and placed in a hopper where it is extruded out of a slit die onto a plastic film (mylar) that is moved along a heated table. The slit of the extruder is parallel to the plane of the table, and, as the mass is extruded into a thin sheet, it passes under a doctor bar to smooth the sheet into the desired thickness. As the sheet is conveyed along the heated table on the plastic film, the solvent binders are cooked off to dry the sheet into a pliable piece that is stiffened yet deformable. The sheet is then cut into desired lengths and hung to dry. This technique is generally preferred where a thin dimensional thickness is desired. 
   b. Dry Pressing 
   Another optional technique to form a raw sheet of ceramic material is the dry pressing process. Here, again, the powdered ceramic, such as zirconia or alumunia, is mixed with a binder as discussed above. A selected quantity of this mass is then placed in a pre-formed mold that is in the shape of the product and is subjected to uniform pressure in a range of approximately 500 psi to 10,000 psi to form the sheet. Where a thick product is desired, dry pressing may be preferred over the tape extrusion process, discussed above. 
   c. Slurry 
   A third optional technique of forming the mass is called the slurry process. The slurry process is less desirable because it typically cannot be used to form thin parts. Here, a very wet cement-like mass of ceramic and binder is formed, typically using a larger ratio of binder to ceramic powder to that used in the dry press or tape extrusion processes. The wet cement-like mass is placed in a form and the excess material is troweled off. The resulting product is then dried to form a raw ceramic sheet. 
   d. Roll Compaction 
   A final method of forming the raw ceramic sheet stock is called roll compaction. Roll compaction is identical to tape extrusion, discussed above, but employs a pressure roller downstream of the doctor bar. The pressure roller is set further to apply a normal force on the extruded sheet to compress the extruded sheet at a desired thickness as a sheet moves thereunder while being conveyed by the moving, heated table. Roll compaction is sometimes desirable because it can produce ceramic sheets faster at a higher yield and have less edge margin curvature than as sometimes occurs with tape extrusion. 
   2. Production Blank Formation 
   In the generalized process, the blade blank formation step  14  is accomplished in any manner wherein a blade blank is cut from a stock of material in its green state, that is, uncured. Thus, for example, an individual blade may be formed and subjected to the further processing steps, discussed below, as is known in the art. 
   3. Green Machining 
   After a production blank is formed, it undergoes a green machining step, at  16  in  FIG. 1 , wherein a cutting edge is formed on the pre-fired blank. For example, with reference to  FIG. 6 , it may be seen that cutting edges  52  and  54  are formed on pre-fired blank  50 . Individual blades  55 - 58  are then cut from pre-fired blank  50  to result in pre-fired blank  70  shown in  FIG. 7 . Cutting edges  62  and  64  are cut on pre-fired blank  70  to form blades  65 - 68  which may be laser cut from pre-fired blank  60  to form pre-fired blank  70 . Pre-fired blank  70 , as is shown in  FIG. 8 , may then have cutting edges  72  and  74  cut thereon and blades  75 - 78  are laser cut therefrom. The step of green machining is accomplished by using an abrasive grinding wheel such as diamond or various ceramic materials as is known in the art. A grinding wheel having an approximate eight hundred grit is typically used. If too rough of a grit is employed, a fine enough edge is difficult to achieve. On the other hand, if too fine of a grit is used, the abraded ceramic will too rapidly plug the grinding wheel. In any event, it is desired in the generalized process to form a sharp enough edge under the green machining step so that no further edge polishing is necessary. 
   4. Heat Treatment 
   After the individual blade is green machined, it is subjected to the heat treatment to sinter the ceramic material, as illustrated at  18  in  FIG. 1 . Here, a plurality of ceramic blocks are placed on a traveling car or carriage, typically mounted to a chain drive which passes through an oven. An initial layer of ceramic blocks is placed and an ensemble of individual blades is then placed on the initial layer of ceramic blocks. A second layer ceramic blocks is then stacked on top of the first layer of blades and a second layer of blades is placed on the second layer of ceramic blocks. This layering continues for approximately six to eight layers with the final layer also being a cap of ceramic blocks. The loaded carriage is then towed through a furnace which is typically at a temperature of approximately 3000° F. The dwell time for the blades in the furnace is approximately four to twelve hours until they are cured. 
   The result of the heat treating step is a hard blade that is no longer pliable, although, when a ceramic matrix of zirconia is employed to form the product, the blade may still slightly flex. Further, depending upon the degree of fineness of the green machining, the blade either has a cured edge or can be finished enough for certain applications, such as those in industrial processes. 
   5. Laser Edge Treatment ( FIGS. 2-4 ) 
   An important processing step in one embodiment of the present invention is the treating of the centered blade edge by means of a laser scan, as depicted at  20  in  FIG. 1  and in greater detail below with respect to  FIG. 20 . With reference to  FIGS. 2 and 3 , it may be seen that an edge  80  of a typically prior art blade is formed of a plurality of ceramic particles  82  which are packed together in a dense matrix. With reference to  FIG. 3 , it may be seen that these particles  82  are individual particles that are not tightly bonded together by the sintering process. Accordingly, and as is the case in prior art ceramic blades, the edge  80  shown in  FIGS. 2 and 3  can deteriorate as a result of individual particles  82  becoming dislodged during use. As the particles  82  are abraded away, the cutting edge becomes duller and duller. 
   To eliminate this, the present invention employs a laser edge treatment in order to provide a microscopic melt on the individual ceramic particles located on the extreme edge of the blade. This is referred to herein as thermal fusing. By this it is meant that the degree of melting is sufficiently more than that which occurs during sintering such that the particles are intimately bonded together. The result is illustrated in  FIG. 4  where it may be seen that particles  82  have melted regions  84  on the microscopic level. When slightly melted together, it has been found that the particles adhere and do not become easily dislodged thereby providing an extremely long lasting and durable cutting edge. 
   Numerous parameters can effect this laser edge treatment. Such parameters include the wavelength of the laser, the wattage of the laser, the thickness of the edge to be treated, the color of the ceramic material, the travel rate of the laser across the edge, the beam width of the laser and the angle of the laser. It has been found that a high energy, high intensity laser is most suitable for flash forming the slightly melted edge. Preferably, an ultra-violet laser is employed. It has been found that a longer wavelength laser will cause cracking of the edge which may be the result of thermal expansion of a ceramic particles. On the other hand, an intense ultra-violet laser will cause localized rapid heating at the surface of the particles allowing them to bond while minimizing any expansion. 
   It has been found that a suitable laser for this laser edge treatment is an ultra-violet laser having a wavelength of approximately 280 nanometers with a hundred to five hundred watt power. For a one and a quarter inch blade (1¼″) it is scanned with a travel rate of approximately 0.1 seconds per inch. Using the zigzag pattern described with respect to  FIG. 21 , it is possible to scan at a rate of 0.3 to 0.6 inches per second. 
   6. Coating 
   After the laser edge treatment is concluded, the resulting edge receives a hard ceramic coating using a sputter-like process, as noted at  22  in  FIG. 1 . Here, a thin layer of chromium nitride or zirconium nitride is on the extreme cutting edge. This can be accomplished by placing an ensemble of blades in a vacuum and depositing chromium or zirconium metal on the blade edge under vacuum. The metal is then undergoes an oxidizing reaction, for example, by introducing nitrogen gas is then introduced into the coating chamber so that a chromium nitride or zirconium nitride coat having a thickness of approximately seven to ten angstroms is placed on the edge. This oxidation step is called “nitriding”. The process is then completed as depicted at  24  in  FIG. 1 . 
   While zirconium nitride and chromium nitride are demonstrated to be effective, other hard ceramic coatings currently known in the industry or hereinafter developed may be useful, as well. For example, titanium nitride, titanium carbon nitride and boron nitride coatings would appear to be suitable. 
   B. Expanded Process ( FIG. 5 ) 
   With reference now to  FIG. 5 , an expanded manufacturing process for blades according to the present invention is diagrammed. Numerous of these steps are similar to the generalized process so need not be discussed again. The process starts at step  110  and a first step is that of ceramic stock formation, at  112 . 
   1. Ceramic Stock Formation 
   Ceramic stock formation step  112  is identical to that with respect to ceramic stock formation step  12 , discussed above so that discussion is not again repeated. 
   2. Production Blank Formation 
   The step of the production blank formation at  114 , is the same as the production blank formation step  14 , discussed above. 
   3. Green Machining 
   The green machining step at  116  is the same as the green machining step  16  discussed at A.3 above so that discussion is not again repeated. 
   4. Blade Blank Formation 
   Regardless of the method of forming the raw ceramic sheet stock, the resulting sheet stock is typically a pliable sheet of a consistency similar to chewing gum. This sheet must then be formed into a production blank, as at  118  in  FIG. 5 , which is normally accomplished, as is known in the art, by a laser cutting process. As is shown in  FIG. 5 , the production blank formation occurs as step  118  wherein a laser beam is used to cut the ceramic sheet, for example, into four to five inch rectangular blanks that may be referred to as a “pre-fired blank”. The cutting of the ceramic sheet is usually accomplished by either a carbon dioxide (CO2) laser or a YAG (yttrium aluminum garret) laser. 
   5. Heat Treatment 
   The heat treatment step  120  is the same as the heat treatment steps  18 , discussed above so that this step is not again described. 
   6. Configure Raw Blade 
   With reference again to the expanded process of  FIG. 5 , the expanded process include a step  122  of configuring the raw blade. Here, any desired contouring of the blade may be undertaken. For example, with reference to  FIG. 9 , a razor blade  200  is shown wherein typically, holes  202  and  204  (or other configuration) is accomplished either by machining the hole or configuration or by laser cutting the hole or configuration. 
   7. Face Lapping 
   In the expanded process, an optional face lapping step is performed after the blade is configured. The purpose of the face lapping step is to grind the blade into a desired thickness. As is known in the art, two large counter-rotating disks are employed in a face lapping process. The blades are placed flat on a surface, typically in a carrier that may be held onto the lower counter-rotating disk, for example, by suction holes. The carrier is then inserted between the counter-rotating wheels and a diamond and/or ceramic slurry is introduced so that the surfaces of the blades may be ground to a desired thickness. Typically, in this step, a typical blade of approximately 0.080 inches in thickness is ground to a thickness of approximately 0.075 inches. While it often suitable to face lap just a single surface of the blade, it should be understood that in some applications, both faces of the blade may be subjected to the face lapping process. 
   8. Hot Isostatic Pressing 
   Another optional step in the expanded process is subjecting the blades to a hot isostatic pressing or “hipping”. The purpose of hipping is to remove flaws that may be internal to the ceramic matrix. Because of the powder formation, there can occur a void in the material. Even though the material, at this point, is typically 99.4% compacted, hot isostatic pressing can increase the compaction to 99.9%. 
   Hot isostatic pressing, noted at  126  in  FIG. 5 , is accomplished by placing the center blade in a rack that is provided with a matrix of tiny holes. The plurality of blades are then inserted in a gas or liquid environment under tremendous pressure. Typical pressures for hot isostatic pressing are in the range of about five thousand to thirty-five hundred thousand (5,000 to 35,000) psi range. If desired, hot isostatic pressing can take place at room temperature, but it is preferred that the temperature be either elevated by an auxiliary heater or allowed to elevate as a result of the application of pressure to a temperature to approximately 200° Fahrenheit. Hot isostatic pressing need only be applied for a relatively short duration, on the order of one (1) minute, in order to achieve the desired increase in compaction. 
   9. Re-lapping 
   When the center blade has been subjected to a hipping treatment, the pressure can sometimes slightly distort the faces of the blade. Accordingly, the faces may be re-lapped, as shown at  128  in  FIG. 5 , to result in flat blade surfaces that are parallel to one another. This re-lapping step is accomplished in the manner identically to that discussed with respect to the step of face lapping, above. 
   10. Edge Formation 
   In circumstances where the green machining has not been sufficient to form the desired shortness of the blade, the blade may undergo a bevel edge formation, as illustrated at  130  in  FIG. 5 . This polish edging is conducted as is known in the art on grinding wheels of various coarseness. An initial bevel is placed using an 8,000 grit diamond wheel followed by beveling with a 12,000 grit diamond wheel and finally, beveling with a 20,000 diamond grit wheel. Depending upon the shape of the wheel and the angle at which the blade is placed on the wheel and the orientation of the blade with respect to the wheel, a variety of different bevels can be achieved. Typically, the blade is placed against the cylindrical surface so that the blade is tangent to the wheel. The plane of the blade is canted at an angle of approximately 60° to 45° with respect to the axis of rotation of the wheel to accomplish the bevel. It is possible to put both convex and concave bevels, compound bevels and straight bevels on a blade edge, as described more thoroughly below. 
   11. Laser Edge Treatment 
   After the edge formation, the beveled edge in the expanded process is subjected to a laser edge treatment at  132 . This laser edge treatment is identical to the laser edge treatment  20  discussed above so that discussion is not again repeated. 
   12. Sputter Undercoating 
   As noted above with respect to the streamlined process, it is desired that the blade edge receive a ceramic coating. To enhance the ceramic coating, it is first desirable to provide a sputter undercoat of pure metal, as noted at  134  in  FIG. 5 . Prior to sputter undercoating the edge margin however, it is helpful to clean the blade. This may be accomplished by soaking the blade in a solvent, such as isopropyl alcohol. After soaking, the blade may be placed in a vacuum chamber and heated to burn off the solvent. 
   After the cleaning solvent is removed, the blade receives the metal undercoat. Here, the metal used for the sputter undercoat is selected to match the desired hard ceramic coating to be subsequently applied. For example, if a chromium nitride coating is desired, the edge of the blade may first be sputtered with pure chromium so that a thin layer chromium metal is deposited directly onto the blade. On the other hand, if a zirconium nitride ceramic coating is desired, the edge is sputtered with zirconium. The purpose of the metal undercoating is to make the blade edge conductive thereby to cause a higher adhesion of the hard ceramic coating in a subsequent process. The sputter undercoating is accomplished by a standard vacuum sputtering process with the metal coating be placed at a thickness of approximately 2-3 angstroms on the blade edge. 
   13. Hard Ceramic Edge Coat 
   The hard ceramic edge coating according to the expanded process is similar to that discussed above with respect to the streamline process and occurs at  136  in  FIG. 5 . Here, the blade having the metal sputter undercoating is placed in vacuum. Metal that is the same as the undercoating provides metal vapor source and nitrogen gas is introduced into the deposition chamber. The nitrogen gas reacts with the metal vapor and deposits as the hard ceramic coating directly on the metal undercoating at a thickness of 7 to 10 Angstroms. Here, again, other hard ceramics might be employed, such as, titanium nitride, titanium carbon nitride and boron nitride. 
   14. Lubricating Coating 
   After finishing the blade with a hard ceramic edge coat, in step  136 , it is desired to apply a flourine based lubricating coating onto the edge to reduce friction during use. One such coating material is a dry film material sold under the name KRYTOX® by the E.I. du Pont de Nemours &amp; Company of Wilmington, Del. Here, the flourine base coating is simply sprayed as a film onto the edge, as depicted at  138  in  FIG. 5 . At this point the process ends at  140 . 
   C. Shapes of Blades 
   As noted above, a variety of different bevels may be obtained. These bevels are shown in  FIGS. 10-17  which represents cross-sections of the extreme blade edge. In  FIG. 10 , blade  300  is shown to have a single bevel  302  formed at an approximate angle “a” of about 40°. In  FIG. 11 , blade  10  has a first pair of faces  311  and  312  formed at an angle “b” of approximately 60° with respect to one another. Face  311  is joined to bevel face  313  at a large acute angle of approximately 170°. Likewise, bevel face  314  is formed at a large obtuse angle of about 170° to face  312 . 
   In  FIG. 12 , blade  320  is formed having a double bevel with faces  322  and  324  being formed at an angle of approximately 45° with respect to one another. In  FIG. 13 , blade  330  is formed by having a pair of convex bevels  332  and  334  forming edge  336 . In  FIG. 14 , blade  340  is shown wherein a pair of concave bevels  342  and  344  form a thin sharp edge  346 . 
     FIG. 15  illustrates yet another bevel configuration. Here, blade  350  has an edge  356  formed by a convex bevel  352  and a concave bevel  354 . Turning to  FIG. 16 , blade  360  has an edge  366  formed by a flat face  362  and a concave bevel  364 .  FIG. 17  shows a blade  370  having an edge  376  formed by a flat face  372  and a convex bevel  374 . Finally,  FIG. 18  shows a blade  380  having an edge  386  formed by flat cutting faces  382  and  384 . Here it may be noted that the faces  382  and  384  are cut at angles that are not symmetric; that is, angle “e” and “f” are different. 
   D. Exemplary Shaving Razor Blade 
   The above described methods may be employed to create a wide variety of blades for different applications including applications in the medical field, industrial field and consumer products field. One such example of blade according to this invention is a shaving razor blade that has been found to have a substantially extended usable lifetime. This blade is best illustrated in  FIG. 19  in the form of a ceramic blade  410  formed of a matrix of ceramic particles having a particle size in a range less than about 0.5 microns. 
   Blade  410  has a ceramic body  412  that terminates in the cutting edge  414 . Ceramic body  12  is formed as a flat plate having a thickness “t” of between about 0.002 inch (0.050 mm) and 0.025 inch (0.635 mm). Here, it is preferred that the blade be extruded to this thickness as opposed to face lapping. In order to form edge  414 , a cutting face  420  is created on a portion of the rectangular ceramic body  412 . This edge can be ground in any manner as described above. Cutting edge  414  is formed by the convergence of a cutting face  420  with the side surface  416  of ceramic body  412 , although the cutting edge could be formed by two converging cutting faces. Cutting face  420  is formed at small acute angle “c” that is within a range of about 10° to 20° but, in this embodiment, may be at an convergent angle of about 14.7°. 
   As is seen in  FIGS. 19 and 20 , a hard ceramic coating  430  extends for a distance “d” from cutting edge  414  along the margin  422  of cutting face  420 . The fabrication method of hard ceramic coating  430  is described more thoroughly below. With this method, the distance “d” would ordinarily be the entire width of the bevel. With respect to blade  410 , this hard ceramic coating is a nitride of chromium or zirconium. 
   Prior to creating the hard ceramic coating  430 , however, it is desirable that shaving razor blade  410  undergo a thermal fusion step to thermally join at least some but preferably a majority of the ceramic particles that are in adjacent contract to one another along contact areas in margin  422 . This is accomplished by a laser edge treatment that may be more fully appreciated in reference to  FIG. 21 . Here, it may seen that the method of thermally fusing the ceramic particles together is accomplished by scanning a laser beam, represented at  440  in a zigzag path along a portion of margin  422  that is adjacent to edge  414 . 
   The laser beam  440  preferably has a spot size that is defined by its diameter at the margin portion  422 . This spot size is about 1.0 micron in diameter. The width “w” of the scanned surface is about 3.5 microns in width, and the scanning step is done at a zigzag pattern wherein the angle “x” between the zigzag lines is about 45°. the selected wavelength of the laser beam is in the ultra violet range, preferably about 280 nanometers, and the scanning is accomplished at a rate of about 0.3 to 0.6 inches per second. The laser employed in this step for producing blade  410  is a 500 watt laser. As before, It is important in performing this step that the margin  422  not be subjected to excessive heat build up since the thermal fusing is done on a very localized area during the scan. 
   As noted above, it is desirable to produce a hard ceramic coating  430  on margin  422  of cutting face  420 . This processing is illustrated in  FIGS. 22-24 . In  FIGS. 22 and 23 , it may be seen that a holder  450  receives a stacked array  452  of individual blades  410 ′ that have not yet had the hard ceramic coating placed thereon. Blades  410 ′, however, do have a cutting edge formed and, if desired for the particular application, have been subjected to the thermal fusing step described with respect to  FIG. 21 . In any event, holder  450  includes a pair of removable flanges  454  that retain blades  410 ′ in the interior thereof with the cutting edges  414  facing opening  456  so that the cutting edges  414  are exposed. 
   A plurality of loaded holders  450  are placed in a vapor deposition unit, such as sputtering device  460  as illustrated in  FIG. 24 . Holders  450  are placed around the perimeter region of chamber  461  in the interior  462  thereof such that openings  456  face radially inwardly. A bar  464  of source metal is located axially in the center of sputtering device  460  and this metal may be, for example, zirconium or chromium. An arc coil  466  extends around the bar of source material  464  in order to provide an electric discharge to vaporize the source metal. 
   Sputtering device  460  is connected to a vacuum source  470  so that chamber  461  is evacuated. Arc coil  466  is energized so that metal particles migrate radially from the bar source material  464  to impact onto the edges  414  of each of the blades  410 ′ and holders  450 . A magnetic array  470  may be provided to enhance the sputtering process. 
   It should be understood that the structure and design of sputtering device  460  is existing equipment and does not form part of the present invention. However, it is desirable according to this invention that a metal coating corresponding to hard ceramic coating  430  be formed on each cutting face of blades  410 ′ adjacent the respective edge  414  thereof. This metal coating is formed at a thickness of approximately 0.7 to 1.0 nanometers. Also, as this coating is being formed, the interior of chamber  461  is exposed to an oxidizing agent from oxidizing agent source  468 . This oxidizing agent is preferably nitrogen that, upon introduction into chamber  461 , reacts with the metal particles being sputtered onto cutting faces  420 . Accordingly, a reduction/oxidization reaction occurs that converts the metal particles, such as chromium or zirconium, into a chromium nitride or zirconium nitride, respectively. A resulting hard ceramic layer having a width “d” corresponding to the bevel width, is deposited on the metal undercoating at the desired thickness of 0.7 to 1.0 nanometers. 
   Accordingly, the present invention has been described with some degree of particularity directed to the exemplary embodiment of the present invention. It should be appreciated, though, that the present invention is defined by the following claims construed in light of the prior art so that modifications or changes may be made to the exemplary embodiment of the present invention without departing from the inventive concepts contained herein.