Abstract: A protective coating system for superalloys is described. The coating is an yttrium enriched aluminide, and can be formed by aluminizing an MCrAlY coated superalloy, wherein during the aluminizing process, aluminum diffuses completely through the MCrAlY coating and into the substrate. The coating system exhibits desirable oxidation resistance and resistance to thermal fatigue cracking.

Abstract: For some applications of slide layers, for example in connecting rod bearings of internal combustion engines, for individual sites of a formed piece, high load bearing capability are required while for other places of the same formed piece good embedding abilities are demanded. A composite material with a slide layer applied by cathode sputtering of a tightly cohesive matrix and an insoluble component distributed statistically in it, is adapted to these opposite demands in that the diameter of the particle of the insoluble material has gradients at predetermined sites, which extend parallel to the surface of the slide layer, and to which slide layer hardness gradients correspond. These gradients are generated during the cathode sputtering process in the substrate to be coated to form a growing slide layer having temperature gradients which are maintained and which extend parallel to the substrate surface.

Abstract: A rotary drill bit is provided for boring earth formations which includes a bit blank and a metal matrix secured to the blank. The metal matrix includes a filler material dispersed therein. Cutting elements are mounted on the exterior face of the bit, and substantially all of the exposed internal and external surfaces of the bit are coated with an erosion and abrasion resistant hardfacing material bonded to the metal matrix.

Abstract: An alloy tool of hard metal has a working part and a non-working part. The working part is made of a hard metal containing carbide of at least a metal selected from a group of elements belonging to the groups IVa, Va and VIa of the periodic table as a basis metal of the hard phase and an iron family metal as a basis metal of the binder phase. The working part includes a region for working a work piece. The non-working part is made of a hard metal containing carbide of at least a metal selected from a group of elements belonging to the groups IVa, Va and VIa of the periodic table as a basis metal of the hard phase of the non-working part and of an iron family metal as a basis metal of the binder phase of the non-working part. A diffused junction between the working and non-working parts bonds the two parts together.

Abstract: This case relates to tough, wear resistant graded structure composites, to a process for preparing the same and to tools and products fabricated therefrom. The composites have a surface layer e.g. of WC and a binder, an interface layer, e.g. which is a stepwise transition from the surface layer whereby the binder content thereof gradually increases, a substrate layer which is a combination of e.g. an initial high carbon steel layer and finally a base layer of bainitic steel. The composites are substantially non-porous and can be used to fabricate components such as drill bits, wear plates, pump components machine tools, seals, washers, bearings and the like.

Abstract: The disclosure relates to a turbine disk and a method of making the turbine disk comprising the steps of rotating a mold, adding a first powdered metal to the rotating mold at a first rate, reducing the rate of addition of the first metal to a second rate, and adding a second powdered metal to the mold at a third rate substantially equal to the difference between the first and second rates.

Abstract: There are disclosed a surface refined sintered alloy body which comprises a hard phase containing at least one selected from the group consissting of carbides, carbonitrides, carbooxides, carbonitrooxides of the metals of the groups 4a, 5a and 6a of the periodic table and a binding phase containing at least one selected from iron group metals, characterized in that the concentration of the binding phase in the surface layer (of from 10 .mu.m to 500 .mu.m from the surface of the sintered alloy) is highest at the outermost surface thereof and approaches the concentration of the inner portion, the concentration of the binding phase decreasing from the outermost surface to a point at least 5 .mu.m from the surface; and a method for making the same by applying decarburization treatment at the surface of the sintered alloy at temperatures within the solid-liquid co-existing region of the binding phase after sintering or in the process of sintering.

Abstract: A method is disclosed for providing an article having within its integral body a plurality of sections of varying density. The method involves successively loading a die with each of a plurality of powders, each powder having a specific composition and particle size and each powder being loaded in a predetermined amount to result in each section of the final article having a characteristic density, compacting the powders to produce a preformed article, and sintering the preformed article at a sufficient temperature for a sufficient time to produce the final article.A method is disclosed in which the powders are metal.A metal article is disclosed which is produced the above methods, with the preferred metals being tungsten powder and molybdenum powder.

Abstract: A method for making seamless, porous metal articles comprising:(a) rotating a mold containing a stabilized suspension of a metal particulate at a rate and for a time such that the particulate is separated from the suspension and distributed on the interior wall of the mold, thereby forming a structure conforming to the interior wall of the mold, the rate of rotation being sufficiently high that, preferably, at least about 65 Gs up to 100 Gs of centrifugal acceleration is achieved at the interior wall of the structure,(b) drying the formed structure to provide a structure having green or unsintered strength, and(c) sintering the dried structure to remove volatile material and fuse the individual particles of the particulate to each other to form the seamless, porous metal article.Metal articles in accordance with the invention have substantially uniform diameters, thicknesses and pore structurs, have Bubble Point ratios of greater than 1.5 up to 2.5, and find particular use as filters.

Abstract: Electrodes for lamps comprising elongated structures comprised of layers containing varying amounts of metal and refractory oxide. In a preferred embodiment the electrode has a first end comprising 9.6 volume percent tungsten and the remainder alumina. The second end comprises substantially 100% tungsten. The intermediate body contains layers of, e.g., 12, 20, 35, 50 and 75% tungsten.

Abstract: A method for making seamless, porous metal articles comprising:(a) rotating a mold containing a stabilized suspension of a metal particulate at a rate and for a time such that the particulate is separated from the suspension and distributed on the interior wall of the mold, thereby forming a structure conforming to the interior wall of the mold, the rate of rotation being sufficiently high that at least about 100 Gs of centrifugal acceleration is achieved at the interior wall of the structure,(b) drying the formed structure to provide a structure having green or unsintered strength, and(c) sintering the dried structure to remove volatile material and fuse the individual particles of the particulate to each other to form the seamless, porous metal article.Metal articles in accordance with the invention have substantially uniform diameters, thicknesses and pore structures, have Bubble Point ratios of 1.5 or less, and find particular use as filters.

Abstract: Light alloy articles comprising a body of light alloy having a composite fiber/light alloy layer, a sprayed heat-resistant alloy layer, and a sprayed ceramic base layer formed on the body in this sequence exhibit improved heat resistance and insulation and are very useful in the manufacture of internal combustion engine pistons. A method for producing such a coated light alloy article by spraying is also provided.

Abstract: A sintered metal part which has a pressed and sintered core; the part is coated with a sintered metal surface layer; the layer has a property different from that of the metal part; the interior regions of the core are free of the metal constituting the coating; and process for making the parts.

Abstract: A method of producing a material having a layer of ceramic as a first component, a layer of a metal as a second component and an intermediate layer lying between said layers and including said first and second components in continuous gradient ratios so that the properties of the material may change continuous, including a step of forming said intermediate layer by igniting a powder mixture of metallic and nonmetallic constitutive elements of said ceramic component and said metal component so as to cause a synthetic reaction in the powder mixture.

Abstract: Described are an aluminium-based article having a heat and corrosion protective coating, especially engine parts such as piston crown or cylinder head, and a method of preparing said article. The coating consists of an aluminium-based bonding layer, preferably having a thickness in the range 0.1-0.6 mm, and an outer top layer of stabilized or partially stabilized zirconium dioxide, preferably having a thickness in the range 0.5-2.5 mm, and optionally a cermet layer, comprising zirconium dioxide and an aluminium-based metal component, between the bonding layer and the outer zirconium dioxide top layer. The bonding layer is applied to the substrate by thermal spraying of a rapidly solidified powder, substantially consisting of 60-80% by weight of Al and 40-20% by weight of Si, the particles of the powder having a frozen unstable micro-structure.

Abstract: A molybdenum article is disclosed in which the substrate thereof has adherently bonded thereto a thermally self-healing plasma-sprayed coating consisting essentially of a composite of molybdenum and a refractory oxide material capable of reacting with molybdenum oxide under oxidizing conditions to form a substantially thermally stable refractory compound of molybdenum. The plasma-sprayed coating is formed of a plurality of interbonded plasma-sprayed layers of a composite of molybdenum/refractory oxide material produced from a particulate mixture thereof. The coating comprises a first layer of molybdenum plasma-sprayed bonded to the substrate of said molybdenum element and a second layer of plasma-sprayed mixture of particulate molybdenum/refractory oxide consisting essentially of predominantly molybdenum bonded to the first layer.

Abstract: This invention provides a shaped, graded, cermet article comprising at least one continuous ceramic phase and at least one discontinuous metal phase, the ratio of ceramic/metal being controlled and varied over the thickness of the article. The ceramic phase preferably is microcrystalline.

Abstract: The present invention relates to a composite bearing material comprising three layers: (1) a metal backing, (2) a porous metal interlayer bonded to the metal backing which includes bronze or other copper alloy particles from two distinct particle size ranges and (3) a PTFE based composition intermixed with and overlying the porous metal interlayer. In accordance with the method of the present invention, the porous metal interlayer substantially comprises a relatively non-homogeneous mixture of particles from the two distinct particle size ranges, wherein a substantial portion of the relatively fine powder is segregated adjacent the metal backing. The present invention includes a significant thickness of the PTFE based composition applied to and remaining above the surface of the porous metal backing.

Abstract: Disclosed herein is a metal-ceramic composite article which includes a metallic member made of a precipitation hardenable alloy and a ceramic member, wherein a projection of the ceramic member is fitted into a hole or a through hole formed in the metallic member and the metallic member of the composite article is hardened through precipitation hardening. A process for manufacturing such a metal-ceramic composite article is also disclosed. The manufacturing process includes the steps of: fitting a projection formed at a ceramic member into a hole formed in the metallic member made of a precipitation hardenable alloy in a state in which precipitation-hardening is not carried out to form a metal-ceramic joint body, and subjecting the thus formed metal-ceramic composite body to a precipitation hardening treatment to harden the metallic member.

Abstract: A metal-ceramic composite article produced by fitting a projection formed on a ceramic member into a hole formed in a metallic member having a hardened region and an unhardened region on its surface such that the ceramic member is monolithically bonded to the metallic member and the deformed region of the metallic member resulting from the fitting is located within its unhardened range, has a high bonding force between the ceramic member and the metallic member and is adapted to be used in engine parts, such as turbocharger rotor, gas turbine rotor and the like, and other structural parts exposed to high temperature or to repeating loads, by utilizing the heat resistance, wear resistance and high strength of the ceramic.

Abstract: A ferromagnetic film for magnetic recording comprises a copper substrate having particles of iron and iron oxides dispersed in the surface layer of the copper. The particles have maximum dimensions in the range between 50 and 500 Angstroms. The ferromagnetic film can be formed by ion implantation of iron ions into the copper substrate followed by heat treatment to permit growth of ferromagnetic particles to the desired size. As an alternative to ion implantation, the iron can be deposited on the copper substrate by sputtering or evaporation and mixed with the copper by ion beam mixing.

Abstract: This invention provides a shaped, graded, cermet article comprising at least one continuous ceramic phase and at least one discontinuous metal phase, the ratio of ceramic/metal being controlled and varied over the thickness of the article. The ceramic phase preferably is microcrystalline.

Abstract: A high strength structural member made of Al-alloy is essentially formed of a sintered body of Al-alloy powder containing Si and Fe in the proportion of 10.ltoreq.Si.ltoreq.30 wt. % and 4.ltoreq.Fe.ltoreq.33 wt. %, and the surface layer of the sintered body is subjected to remelting-solidifying treatment with a high-density energy source such as a laser beam, a plasma arc, a TIG arc, etc. In the treated surface layer of the sintered body, grain sizes of Si crystal grains and precipitated intermetallic compound are reduced to 1 .mu.m or smaller, whereas in the base portion of the sintered body that is not subjected to the remelting-solidifying treatment, grain sizes of Si crystal grains and precipitated intermetallic compound are kept 10 .mu.m or smaller.

Abstract: A sintered metal body with at least one toothing thereon and a method of forming the same. The toothing is formed in a sintered metal blank with or without pre-toothing by metal forming. The final toothing is cold rolled into the sintered metal blank. The thus formed sintered metal body with at least one toothing can be used for highly stressed toothed gears, such as involutes, cycloids, and epicycloids, as used, for example, on bevel gears, and particularly curved-toothed bevel gears.

Abstract: A gas permeable or porous article of irregular configuration comprising a sintered structure of dispersion strengthened metal or metal alloy particles. The present invention also relates to a novel method for making such article.

Abstract: Disclosed is a gas turbine disk made from powder metal, wherein the bore has improved fatigue life compared to conventional articles because the bore is formed from a fine fraction of powder separated from a lot of conventional powder metal suitable for hot isostatic compaction. The outer and rim portions of the disk, which are less prone to fatigue failure, are made from the remainder of the lot but nonetheless have no more limited performance from that resulting when a unitary unseparated powder lot is used. Improved bore fatigue properties result because the coarse fatigue failure-causing nonmetallic inclusions are biased into the outer portions of the disk where they do not have adverse effect.

Abstract: The connection of a ceramic rotary component to a metallic rotary component for a turbomachine such as a gas turbine engine wherein the ceramic rotary component comprises a sintered rotor disk of reaction bonded silicon nitride (RBSN) or silicon carbide sintered under no pressure and the metallic rotary component is formed by the hot isostatic pressing of a metallic powder. The metallic rotary component becomes bonded to the sintered rotor disk to form a secure connection therewith. The metallic powder has a coefficient of thermal expansion substantially equal to that of the ceramic rotary component.

Abstract: Disclosed herein is a method of making a plastic casing with a conductive film which is effective to screen electromagnetic waves and prevent electrification. The method comprises the steps of removably coating a conductive material containing coarse conductive powder onto a mold surface of a mold set for forming a plastic casing, drying the coated conductive material to form a solidified film, injecting a fluidized thermoplastic material under high pressure into the mold set, and compressing the solidified film by the high temperature and high pressure of the thermoplastic material, thereby anchoring the solidified film to the contact surface of the molded casing opposite to the solidified film. The conductive film of the plastic casing thus made has a highly aggregate layer in which the particles of conductive powder are densely collected into point-to-point and/or surface-to-surface contact so that the contacting area of the particles is vastly increased.

Abstract: Wear-resistant coating on a machine part which is subject to friction wear, the coating being applied by a flame spray process and being composed of a plurality of superposed sprayed-on layers each differing in structure or composition from each layer adjacent thereto.

Abstract: Cemented carbide substrates having substantially A or B type porosity and a binder enriched layer near its surface are described. A refractory oxide, nitride, boride, and/or carbide coating is deposited on the binder enriched surface of the substrate. Binder enrichment is achieved by incorporating Group IVB or VB transition elements. These elements can be added as the metal, the metal hydride, nitride or carbonitride.

Abstract: An additive process, for manufacturing multiple- (single or double) sided printed circuit boards, which advantageously provides substantial adhesion, very fine resolution and significant manufacturing time and cost savings over prior art processes, is disclosed. Specifically, a seed layer, comprised of conductive particles, such as carbon, dispersed throughout a binder capable of adhering to an unclad insulating printed circuit board substrate, is first applied over pre-defined locations on each surface of the substrate above which corresponding portions of a conductive pattern are to appear. This seed layer is also applied to coat substantially all the surface area of the walls of one or more holes formed through the substrate which are, in turn, to become plated-through holes. Thereafter, a conductive layer, such as copper, is electrolytically plated onto the seed layer in order to produce the conductive pattern and the plated-through holes.

Abstract: A journal assembled to a rotary shaft has its outer portion made of solid phase sintered alloy having 10% to 30% by volume of sintering pores inpregnated with lubricating oil and its inner portion is made of a liquid phase sintered alloy being sinterable at the same temperature as the solid phase sintered alloy. The outer portion is wear-resistant and well lubricable due to the oil impregnated therein. The inner portion is tightly secured to both the outer portion and the rotary shaft because the liquid phase sintered alloy is metallurgically diffusion-bonded to both the solid phase sintered alloy and the rotary shaft.

Abstract: The invention relates to cylinder liners for internal combustion engines comprising a matrix based on aluminum alloys of high mechanical strength, obtained by powder metallurgy, and methods of producing them. The liners comprise a dispersion of grains of an added intermetallic compound, apart from the dispersion of such intermetallic compounds as may exist in the alloy, the added compound having a melting temperature of over 700.degree. C. The liners are obtained by extruding or sintering a mixture of powders. The liners of the invention may be used particularly in the automobile industry and in any kind of industry where liner-piston units of good compatibility must be obtained from aluminum alloys.

Abstract: Apparatus for the production of a metal article comprises means for maintaining a reservoir of molten metal with a free surface, means for rotating the free surface of the reservoir about an axis such that the molten metal is atomized and thrown outwardly away from the said surface by centrifugal action, and a substrate in the path of the atomized particles of said molten metal, whereby a solid article may be built up on the substrate by solidifying the atomized particles thereon. The molten metal may be produced by melting an electrode or otherwise.An annular solid metal article is disclosed having excellent mechanical properties. The solid metal article is produced in a single step by a spray deposition process. Molten metal is centrifugally atomized to splat and build up on a cooled mold surface disposed around the centrifuge means. Controlled relative reciprocatory movement in the direction of the rotational axis of the centrifuge is provided.

Abstract: Structure coated with graded ceramic material and methods of coating application are disclosed. Techniques for maintaining low stress to strength ratios across the depth of the coating are discussed.In one particular structure the coating is applied to a metal substrate (12) and comprises a metallic bond coat (14), a first interlayer (16) of metal/ceramic material, a second interlayer (18) of metal/ceramic material having an increased proportion of ceramic and an all ceramic layer. Modulation of the metal substrate temperature during the coating process establishes a desired residual stress pattern in the part.

Abstract: An isentropic compressive wave generator and method of making same. The w generator comprises a disk or flat "pillow" member having component materials of different shock impedances formed in a configuration resulting in a smooth shock impedance gradient over the thickness thereof for interpositioning between an impactor member and a target specimen for producing a shock wave of a smooth predictable rise time. The method of making the pillow member comprises the reduction of the component materials to a powder form and forming the pillow member by sedimentation and compressive techniques.

Abstract: The object of the invention is a process of manufacturing a sintered compact of sinterable pulverulent material, in which the powder is moulded against a moulding surface and sintered in contact with the moulding surface and in which the pores in at least local areas of the compact are sealed by infiltration with an infiltration material which during a stage of the infiltration process is in liquid form and which by temperature decrease is caused to solidify in the pores, and the characteristic features of the invention are that the moulding takes place on the moulding surface in such a way that the moulding surface is covered with relatively fine-grained sinterable powder which by its own adhesion or by adhesion intensified by additives is caused to form an at least temporarily retained fine powder layer (3) on the moulding surface, and that at least one layer (5) of sinterable coarse powder is applied to the fine powder layer, and that both layers are sintered and infiltration is effected such that the infi

Abstract: The invention relates to a method for manufacturing tubes by sintering and infiltration, the characteristic features of the invention being that the tube wall is formed from a metal powder on a mandrel and is sintered and that the tube wall, during one sintering stage, is sealed by infiltration by means of an infiltration material which solidifies in situ when the temperature is lowered after sintering and which is capable, when in the liquid state, of wetting the metal powder particles, the molding of the tube from the metal powder being preferably carried out by a wet or dry pressing process or by extrusion of the metal powder.

Abstract: A corrosion- and abrasive wear-resistant composite material for use in centrifugally cast linings composed of a matrix of a metal having corrosion-resistance and an abrasive wear-resistant reinforcing material dispersed as particles in the matrix. The reinforcing material has a higher hardness and a smaller specific density than the matrix.

Abstract: A method is disclosed for forming roller cutters and also for forming cutting teeth for rolling cutter bits, including cutter inserts, cutter teeth formed in place, or formed separately and welded in place, etc., by powder metallurgy as a densified powder metallurgical composite of at least two varying phases, the composite having a substantially continuous mechanical property gradient therethrough. The gradient is from one region having hardness or wear resistant properties to another region having toughness properties. The method comprises:providing a first powder mixture comprising a major proportion by volume of a powdered refractory compound and a minor proportion by volume of a powdered binder metal or alloy. Providing a second powder comprising a powdered binder metal or alloy or a mixture comprising a powdered refractory material and a powdered binder metal or alloy, present in a lesser proportion by volume than in the first powder.

Abstract: A method of thread rolling a cylindrical sintered P/M blank is provided comprising, forming a sintered cylindrical powder metal (P/M) blank of density ranging from about 75% to 92% of the actual density of said metal blank having a selected diameter larger than the final pitch diameter of a predetermined roll threaded product produced therefrom and not substantially exceeding the outside diameter of said predetermined roll threaded product. The P/M blank diameter selected is substantially inversely related to the density of the blank, the P/M diameter selected being correlated to produce a substantially full thread. The sintered P/M blank is then thread rolled using a threading die corresponding to the gage of the predetermined roll threaded product to be produced.

Abstract: A method of making a coated tip for cutting purposes having a lower degree of flank and crater wear and reduced chipping. A WC-based ultrahard alloy containing WC, at least one nitride selected from among TiN, TaN and NbN and a bonding metal is heat treated at a temperature of 800.degree. C. to 1,300.degree. C. in a nitrogen atmosphere for a sufficiently long period of time to cause nitride in a layer in the vicinity of the surface of the alloy to move to the surface to form a layer of nitride thereon as well as an alloy layer of WC and the bonding metal in which the nitride has been reduced. The surface of the tip is then coated with a layer of Al.sub.2 O.sub.3.

Abstract: A method of fabricating a rock bit insert which has improved wear characteristics is disclosed. Selected surfaces of the insert are implanted with a harder grade of tungsten carbide and sintered thereto. The special insert then would find application in the gage row of, for example, a roller cone rock bit.

Abstract: The present invention relates to a sintered porous metal plate which comprises metal particles directly and integrally bonded together by sintering under pressure, said plate being of a porous structure and having a density gradient in the direction of thickness. The present invention is also directed to a method of making such a sintered porous plate.

Abstract: An implantable bone replacement material (body) based on completely or partially resorbable particles incorporated in a matrix material. The particles are composed of bioactive sintered calcium phosphate ceramic material having a CaO:P.sub.2 O.sub.5 composition ratio between 3:1 and 4:1. The replacement material (body) consists of a metal containing calcium phosphate ceramic material in the form of a monolayer of particles in the peripheral areas of the material (body) which serve as interfaces to the body tissue. The metal is compatible with body tissue. The ceramic particles have a size range between about 500 .mu.m and a few millimeters. The calcium phosphate particles are located so that they lie exposed on the upper surface of the material (body). Other embodiments and processes are also disclosed.

Abstract: The present invention relates to powder metal articles that can be successfully welded to ferrous base materials. A formed part having an initial part density of at least 5.8 grams per cubic centimeter subsequently compressed is to at least ninety-two per cent (92%) of theoretical full density at a controlled area, including a contact area at which the part is adapted to be welded to the other material and at least a 0.025 inch wide margin of the surface laterally contiguous the contact area to a subsurface depth of at least 0.025 inch while retaining the initial part density throughout the balance of the article. Such increased densification is accomplished by applying inwardly directed, localized surface pressure against the controlled area of a formed powder metal part.

Abstract: A hot-cathode material in wire or sheet form, comprising a high-melting carrier metal, an oxide activator and a carbide reducing agent, and, optionally, a diffusion-promoting additive, the material comprising a core zone and at least one surface layer having different compositions or different concentrations of constituents therein which are such that, in operation, the rate of diffusion of the activator from the core zone is equal to or greater than the loss of activator from the surface layer. The material is made by a powder metallurgy/thermo-mechanical process.

Abstract: A sintered metal article such as a piston ring or a sealing ring (in particular those having a cross-section area not exceeding 20 mm.sup.2) having a density which is at least 88.5% of the theoretical density, having a fine machined surface finish, and having a nitrocarburized surface layer which is not found at a depth of more than about 250 microns from the surface.The invention also includes the process of manufacturing such an article.

Abstract: The method produces an article which has a first zone comprising a nonoxide ceramic material (which materials cannot be soldered or welded) and a second zone comprising a different, softer material such as one which can be soldered or welded to other parts. A transition layer between the zones of the article comprises both materials for bonding the zones together. The method forms the article from powders with heat and pressure.

Abstract: A process for increasing the resistance to wear of the surface of hard metal parts subject to wear, such as a cutting blade of metal cutting tools, and the product which results from the process, which includes coating the surface of the hard metal, for example, cemented carbide articles with a first layer comprised of one or more layers of a metallic carbide or nitride in a total thickness ranging from 0.01 to 10 .mu.m, a second layer comprised of one or more layers of a refractory oxide, such as an oxide of aluminum, zirconium, silicon, calcium, magnesium, titanium, and hafnium, and stabilized zirconium oxide in a total thickness ranging from 0.5 to 10 .mu.m, and depositing over the refractory oxide coating a third layer comprised of one or more layers of a nitride, carbonitride, oxynitride, oxycarbide or oxycarbonitride .[.and boride.]. of such metals as titanium, zirconium, hafnium, aluminum and silicon in a total thickness ranging from 1 to 10 .mu.m.