Abstract: A C/C composite including a carbon matrix and carbon fibers and exhibiting a crystal structure of the carbon matrix differing between (a) the portion at and in the vicinity of the interface between the carbon fibers and the carbon matrix and (b) the other portion of the carbon matrix and excelling in strength and thermal conductivity is produced by a method which includes intercalating a carbonizing catalyst in carbon fibers, causing said carbon fibers having said carbonizing catalyst intercalated therein to be impregnated with a precursor of a carbon matrix, and then firing the product of impregnation.

Abstract: An improved method and apparatus are disclosed for producing large area diamond depositions. A mixture of a carbon compound such as methane, hydrogen and argon is introduced into a DC arc plasma torch to form a plasma jet. The plasma jet is directed and trapped into a partially enclosed chemical vapor deposition zone confined within a reaction chamber of a CVD process. The chemical vapor deposition zone is formed by walls wherein at least one such wall is a rotating substrate cooled to a set temperature. The plasma jet containing radicalized hydrogen and a carbon compound is impinged on the rotating substrate to produce large area diamond layer.

Abstract: A method of manufacturing a free standing perovskite lead scandium tantalate film. A film of lead scandium tantalate is formed on a layer of MgO deposited on a sapphire substrate. The MgO layer is etched by phosphoric acid thereby releasing the lead scandium tantalate film from the substrate.

Abstract: Novel ceramic filamentary micro-tubular materials are described. An entirely fluid-phase method has been devised for producing such interwoven ceramic filamentary tubular materials. The process depends for its success the ability to generate a three-dimensional random weave of ceramic tubes, with diameters in the range of about 0.01 to 2.0 microns, by forming carbon filaments by catalytic decomposition of a hydrocarbon feed, coating the filaments with a ceramic coating and then oxidizing the coated filaments to remove the carbon core leaving behind hollow ceramic micro-tubular filaments. The ceramic micro-tubular materials may be free-standing porous structures and may have a variety of uses as thermal insulators, catalyst supports, superconductor supports, filters or as reinforcements for composites.

Abstract: Method of fabricating free-standing diamond films by depositing and adhering polycrystalline diamond by hot filament chemical vapor deposition (1-100 Torr, filament temperature equal to or greater than 1900.degree. C., substrate temperature of 650.degree.-950.degree. C.) onto a substrate meltable at a temperature slightly in excess of the deposition temperature; and (b) prior to cooling said polycrystalline diamond particles, increasing (50.degree.-300.degree. C.) the substrate temperature to melt at least a portion thereof while permitting such melt to emigrate from the diamond films.

Abstract: A method and apparatus for selectively depositing a layer of material from a gas phase to produce a part comprising a plurality of deposited layers. The apparatus includes a computer controlling a directed energy beam, such as a laser, to direct the laser energy into a chamber substantially containing the gas phase to preferably produce photodecomposition or thermal decomposition of the gas phase and selectively deposit material within the boundaries of the desired cross-sectional regions of the part. For each cross section, the aim of the laser beam is scanned over a target area and the beam is switched on to deposit material within the boundaries of the cross-section. Each subsequent layer is joined to the immediately preceding layer to produce a part comprising a plurality of joined layers. In an alternate embodiment of the present invention, a gas phase is condensed on a surface and a laser beam is used to selectively evaporate, transform, activate or decompose material in each layer.

Abstract: A multiple cavity mold for lipstick products includes a plurality of receptacles. Each receptacle has an inner cavity and an outer surface that is exposed such that a coolant, which is circulated about the receptacle, causes a cosmetic melt contained therein to solidify.

Abstract: An electrode for medical applications can be manufactured with different geometries, and particularly in the form of hollow bodies, by depositing pyrographite on a shaped body of glassy carbon. The deposition is achieved by means of the pyrolysis of hydrocarbons at temperatures ranging approximately from 1800.degree. to 2100.degree. C. After cooling, the pyrographite coating is removed from the shaped body and a pyrographite electrode is produced from the coating.

Abstract: The invention relates to the manufacture of a composite material part by shaping a fibrous reinforcement texture and densifying the texture by chemical vapor infiltration of the material constituting the matrix of the composite through the porosity of the texture. Before densification, the texture is separated from an adjacent structure, such as an adjacent surface of a tool (12, 14) inside which the texture is held, or another texture, by means of an inserted layer (10) of fabric produced in a refractory material having a thermal expansion coefficient different from that of the constituent material of the texture.

Abstract: A method of repairing an eroded refractory wall pierced by one or more openings using a ceramic welding technique. A member of shape substantially complementary to the desired shape of the repaired opening is placed into each opening so that the member projects from the refractory wall by an extent at least equal to the local depth of erosion. Such complementarily-shaped member is so composed that it is adapted to withstand ceramic welding temperatures. A desired refractory repair mass is built up, by ceramic welding, adherent to the eroded wall and surrounding the complementarily-shaped members(s) while leaving its end or their ends exposed, and the complementarily-shaped member(s) is or are thereafter removed from the repaired openings(s). Such complementarily-shaped member may, for example, be of refractory carbon or of steel, such as stainless steel. Such a steel member may be tubular for the circulation of coolant.

Abstract: Method of making selected phases of nanocrystalline ceramic materials. Various methods of controlling the production of nanocrystalline alpha alumina and titanium oxygen phases are described. Control of the gas atmosphere and use of particular oxidation treatments give rise to the ability to control the particular phases provided in the aluminum/oxygen and titanium/oxygen system.

Abstract: Polymeric molds and polymeric mold inserts which have been modified by a plasma treatment process. These modified molds and mold inserts may be used to manufacture improved molded cosmetic products such as lipsticks, giving these products a uniform high-gloss finish.

Abstract: Particulate matter having precisely controlled length, width, thickness (i.e., height) and shape is produced with photolithographic techniques using a release film. In accordance with the method, a first photoresist layer is cured upon a substrate and a second photoresist layer is selectively cured upon the first photoresist to provide a desired pattern. The uncured portions of the second photoresist layer are removed so that a plurality of first and second deposition sites are produced wherein each said first and second deposition site has the desired area and wherein each first deposition site is located in a first plane and each second deposition site is located in a second plane. Further, portions of the substrate which are not part of the first deposition site are not located in the first plane and portions of the substrate which are not part of a second deposition site are not located in the second plane. The desired material is deposited using line-of-sight chemical deposition techniques.

Abstract: A process of repairing a refractory body, including the steps of a. introducing combustible particles into a first gas stream containing no more than 18% oxygen by volume; b. causing an oxygen-rich gas stream to flow through a particle entrainment zone into a reaction zone adjacent a refractory body to be repaired so as to produce an aspirating effect within the particle entrainment zone effective to induce a flow of the first gas stream containing the combustible particles into the particle entrainment zone and through to the reaction zone; and c. projecting the combustible particles entrained in the oxygen-rich gas stream against the refractory body to cause oxidation of the combustible particles in the reaction zone adjacent the refractory body and generate sufficient heat for one of dressing the refractory body or forming a refractory weld mass thereon.

Abstract: Novel ceramic filamentary micro-tubular materials are described. An entirely, fluid-phase method has been devised for producing such interwoven ceramic filamentary tubular materials. The process depends for its success the ability to generate a three-dimensional random weave of ceramic tubes, with diameters in the range of about 0.01 to 2.0 microns, by forming carbon filaments by catalytic decomposition of a hydrocarbon feed, coating the filaments with a ceramic coating and then oxidizing the coated filaments to remove the carbon core leaving behind hollow ceramic micro-tubular filaments. The ceramic micro-tubular materials may be free-standing porous structures and may have a variety of uses as thermal insulators, catalyst supports, superconductor supports, filters or as reinforcements for composites.

Abstract: A method of forming a polycrystalline film, such as a diamond, on a foreign substrate involves preparing the substrate before film deposition to define discrete nucleation sites. The substrate is prepared for film deposition by forming a pattern of irregularities in the surface thereof. The irregularities, typically craters, are arranged in a predetermined pattern which corresponds to that desired for the location of film crystals. The craters preferrably are of uniform, predetermined dimensions (in the sub-micron and micron size range) and are uniformly spaced apart by a predetermined distance. The craters may be formed by a number of techniques, including focused ion beam milling, laser vaporization, and chemical or plasma etching using a patterned photoresist. Once the substrate has been prepared the film may be deposited by a number of known techniques. Films prepared by this method are characterized by a regular surface pattern of crystals which may be arranged in virtually any desired pattern.

Abstract: A method for making a lightweight structure having a high stiffness to weight ratio comprising providing a substrate defining at least a pair of outer surfaces spaced from each other, boring at least one hole through the structure to provide at least one void passage extending through the substrate between the outer surfaces, coating the outer surfaces of the substrate and the surfaces of the passage with a chemical vapor deposited material to a thickness of about one millimeter, plugging the void passage with a plug of a substrate material, and further coating the coated outer surfaces of the substrate and the ends of the plugs with a chemical vapor deposited material to form a continuous monolithic structure thereon.

Abstract: A process for producing a boron nitride crucible having a closed end, an open end, an internal surface and an external surface, and wherein at least a portion of the external surface, preferably proximate the open end of the crucible, is coated with a duplex layer comprising a first coating of pyrolytic graphite and a top coat of pyrolytic boron nitride.

Abstract: A process to fabricate lightweigth ceramic mirrors, and in particular, silicon/silicon carbide mirrors, involves three chemical vapor deposition steps: one to produce the mirror faceplate, the second to form the lightweight backstructure which is deposited integral to the faceplate, and the third and final step which results in the deposition of a layer of optical grade material, for example, silicon, onto the front surface of the faceplate. The mirror figure and finish are fabricated into this latter material.

Abstract: A process for making a carbon-carbon composite having a combination of high crystallinity, high strength, high modulus and high thermal and electrical conductivity. High-modulus/high-strength mesophase derived carbon fibers are woven into a suitable cloth. Layers of this easily graphitizable woven cloth are covered with petroleum or coal tar pitch and pressed at a temperature a few degrees above the softening point of the pitch to form a green laminated composite. The green composite is restrained in a suitable fixture and heated slowly to carbonize the pitch binder. The carbonized composite is then impregnated several times with pitch by covering the composite with hot pitch under pressure. The composites are given a heat treatment between each impregnation step to crack up the infiltrated carbon and allow additional pitch to enter the microstructure during the next impregnation cycle. The impregnated composites are then given a final heat treatment in the range 2500.degree. to 3000.degree. C.

Abstract: The invention relates to a process of making a high purity silicide target comprising the steps of providing a substrate in a CVD enclosure, evacuating said enclosure up to a pressure P1 which is at least equal to or smaller than 5.times.10.sup.-5 Torr, heating the substrate at a temperature T1, which is at least equal to or greater than 20.degree. C., injecting in said enclosure a refractory metal halide MXm having a purity, as far as metallic impurities are concerned, greater than 5N (99,999%) and a silicon hydride having a purity, as far as metallic impurities are concerned, greater than 6N (99,9999%) setting the pressure in the enclosure between about 0.01 Torr and the atmospheric pressure while maintaining the temperature in the CVD enclosure between about 20.degree. C.

Abstract: A process relating to the manufacture of a composite component comprising a web and a reinforcement structure. The process includes providing a profiled section constituting a fibrous structure that is rigidified by impregnation with a thermoformable binder. The profiled section provided has a cross-section corresponding to the dimensions of a non-compacted blank of the component to be formed in a single unit with the web and the reinforcement structure. A blank of the component to be produced is machined from a length of the profiled section. The blank is press formed to obtain a preform having a shape and dimensions approximating those of the component to be produced and the preform is densified by chemical vapor infiltration of a material constituting a matrix within the fibrous structure, after elimination of the thermoformable binder.

Abstract: A process for the consolidation of discrete, particulate, low-melting or liquid materials, characterized in that said materials are consolidated in their particulate discrete form by application of vapors of at least one p-xylylene monomer and/or of a derivative thereof, which is polymerized under vacuum. The materials are thus given the surface characteristics of a solid, with enhanced properties of mechanical, physical and/or chemical strength, even in the presence of high temperatures. The invention is particularly useful for the metered addition of predetermined amounts of compositions or for moving mechanical parts.

Abstract: Conducting articles such as fibers, films, tapes and the like are fabricated from intractable conducting polymers such as polyacetylene. The articles are prepared by (a) forming a gel of a carrier polymer in a compatible solvent, (b) polymerizing, within the gel, a selected monomer, and (c) doping the article so provided. The articles are highly electrically conductive as well as mechanically quite strong.

Abstract: A composite gas turbine engine blade is made by braiding a plurality of fibers to form a preform having an airfoil precursor portion and an integral root precursor portion. A plurality of fiber shaping inserts are positioned in the root precursor portion, either by braiding the root precursor portion around the inserts or inserting the fiber shaping inserts into the root precursor portion after braiding, to impart an enlarged, divergent shape (e.g., dovetail precursor shape) to the braided root precursor portion. The braided preform with the enlarged, shaped root precursor portion is infiltrated with matrix material and shaped to near net shape to provide the composite blade with a dovetail shaped root.

Abstract: A method and apparatus for selectively depositing a layer of material from a gas phase to produce a part comprising a plurality of deposited layers. The apparatus includes a computer controlling a directed energy beam, such as a laser, to direct the laser energy into a chamber substantially containing the gas phase to preferably produce photodecomposition or thermal decomposition of the gas phase and selectively deposit material within the boundaries of the desired cross-sectional regions of the part. For each cross section, the aim of the laser beam is scanned over a target area and the beam is switched on to deposit material within the boundaries of the cross-section. Each subsequent layer is joined to the immediately preceding layer to produce a part comprising a plurality of joined layers. In an alternate embodiment of the present invention, a gas phase is condensed on a surface and a laser beam is used to selectively evaporate, transform, activate or decompose material in each layer.

Abstract: A method of flame spraying refractory material for in situ repair of, e.g., furnace linings wherein an inert carrier gas incapable of supporting combustion and particles of refractory oxide and combustible metal or other oxidizable material are delivered to a flame spraying apparatus wherein high pressure oxygen aspirates and accelerates the carrier gas-particle mixture; a controlled ratio of 5 to 1 to about 30 to 1 oxygen gas to carrier gas; allows for the use of highly combustible metals and materials such as chromium, aluminum, zirconium, and/or magnesium as heat sources without back-flash and at a deposition rate in excess of 2000 pounds per hour of refractory oxide to yield a deposited refractory mass exhibiting enhanced wear and erosion resistance.

Abstract: The formation of an openwork structure e.g., of metal, utilizing low-temperature arc vapor deposition on a foam which is destroyed by pyrolysis is enhanced by applying a portion of the metal in a metal spray of powders in a binder which is also pyrolytically destroyed. The product has essentially the same properties as one made exclusively by the low-temperature arc vapor deposition method.

Abstract: A method for producing a carbon electrode which includes directly depositing a carbon material on an electroconductive electrode substrate by chemical vapor deposition using hydrocarbons and/or their derivatives as a starting material, and subjecting the substrate coated with the carbon material to an electrochemical treatment so that the carbon material is doped with a charge carrier material capable of being reversely intercalated therein and deintercalated therefrom. Thereafter, the electrochemically treated substrate is compressed, and a thin plate-shaped carbon electrode with a high density results.

Abstract: A crystalline diamond film is formed on a thin substrate. Energy is applied by a thermal plasma torch to a gas mixture to deposit carbon particles onto the substrate. The substrate is positioned on a pedestal with a cooling facility in which an intermediate layer of thermally conductive powder is interposed between the substrate and the pedestal.

Abstract: A reactor having a heated liner for producing silicon by chemical vapor deposition (CVD) and means for supplying a gas stream in the turbulent flow region. A gas stream including a silicon-containing compound is passed through a deposition chamber at turbulent flow rates for deposition of silicon on a non-reactive substrate liner heated above the decomposition temperature of the silicon-containing compound. Optionally, the liner is removable from the reactor for separation of deposited metal. Also optionally, the temperature of the liner in situ may be raised above the melting point of the deposited metal for melt out and recovery.

Abstract: A method of increasing the life of tuyere area refractories through repeated application of coherent refractory mass formed by ceramic welding process onto worn area after installing protective removable, expendable or reuseable pipes/rods. Consecutive use of this process can effectively suspend or reduce or control the wear of the original refractories.

Abstract: An openwork nickel structure having a high surface area to volume ratio and a porosity which is largely independent of the degree to which the metal structure may be compressed, is formed by depositing on a pyrolyzable support, preferably a reticulated open-pore polyurethane support, a coating of metal by arc-striking utilizing at least one electrode of that metal and by bringing the electrodes out of contact with one another. The metal-covered support is then subjected to pyrolysis to form the metal skeleton which is then sintered. The resulting metal structure has been found to be suitable for use as an electrode in a Ni-Cd cell.

Abstract: A process for producing an acoustic diaphragm of carbonaceous material including the steps of uniformly depositing vapor phase thermally decomposed carbon generated by the thermal decomposition of a carbon-generating material introduced together with a carrier gas on the surface of a diaphragm-shaped base material and separating the obtained thermally decomposed carbon deposit from the diaphragm-shaped base material. Thus, the diaphragm is inexpensively made of a carbon material having a large E/.rho. value, high elasticity and high accuracy, without cracking.

Abstract: A method for the production of a carbon electrode includes directly depositing a carbon material on an electroconductive and flexible electrode substrate by chemical vapor deposition using gaseous hydrocarbons as a starting material, filling the carbon material directly deposited on the electrode substrate with a charge carrier material capable of being reversibly intercalcated therein and deintercalated therefrom, and compressing the electrode substrate filled with the charge carrier material, resulting in a thin plate-shaped carbon electrode.

Abstract: Virtually uncrosslinked polyacetylenes in film form are prepared by polymerization of acetylene using a liquid catalyst system consisting of an organicaluminum compound and a titanate in the form of a solution in a viscous inert liquid on a substrate to which the catalyst solution is applied, by a process in which, after the polymerization, the polymer is treated with a strong reducing agent which is inert to the organoaluminum catalyst component, the polymer is, if desired, oriented and is freed from residual catalyst and reducing agent by washing with a liquid, doped with a strong electron acceptor or electron donor in a conventional manner to increase the conductivity and dried, and the materials thus obtained are, if desired, covered with a layer or sheath of nonconductive material.

Abstract: A molding apparatus for molding a clay pigeon includes a bypass tube having a tip disposed in a blow orifice communicating with a cavity of a metal mold in the form of the clay pigeon. The bypass tube has a diameter smaller than that of the blow orifice and compressed air, which leads molding material in the blow orifice, passes therethrough in order to supply the molding material mixture of at least sand and hardening agent to the cavity, whereby corners and details of the cavity are satisfactorily filled with the molding material supplied to the cavity.

Abstract: A process for producing an acoustic diaphragm of carbonaceous material including the steps of impregnating nonwoven fabric or woven fabric of carbon fiber having a high degree of elasticity with a thermosetting resin, thermally molding it into a diaphragm shape, calcining the shaped fabric in an inert gas atmosphere to obtain a porous carbon molding, heating the porous molding to a uniform temperature, and depositing vapor phase, thermally decomposed carbon upon a surface of the porous molding. The deposited carbon is generated by thermal decomposition of a hydrocarbon-containing material introduced together with a carrier gas. The process produces an acoustic diaphragm having a dense surface layer of carbonized fiber-carbonized thermosetting resin-thermally decomposed carbon, and a porous interior of carbonized fiber bonded together by carbonized resin and the thermally decomposed carbon.

Abstract: A method for manufacturing ultrafine particles of hardly water-soluble or water-insoluble organic compounds is disclosed herein, and the method includes heating and evaporating the organic compound in a vacuum vessel in which an inert gas is introduced in a desired pressure, then condensing and depositing the vaporized organic compound on a recovering means cooled, the resulting ultrafine particles exhibiting a high negative zeta potential sufficient to form a stable water dispersion thereof.

Abstract: A pellet injector for injecting pellets of condensed gas, such as hydrogen, tritium or deuterium, into a reactor comprises an arrangement of pipe guns in a cylindrical arrangement. Each pipe gun which may be made from stainless steel, has a freezing section and three axially spaced metal rings of a heat conductive metal arranged in good thermal contact with the outer surface of the pipe gun at the freezing section thereof. Each of the rings is thermally connected to a cryostat, for example by means of a copper wire. The center ring is cooled to a temperature below the condensing temperature of the gas so as to condense the gas in the freezing section of the pipe gun to form a pellet therein, and the temperature of the adjacent outer rings are maintained at temperatures exceeding the temperature of the center ring so as to obtain a pellet of a desired size. The pellets formed in the pipe guns may be expelled therefrom by a pressurized gas force pulse and injected into a reactor.

Abstract: An apparatus and process for the chemical vapor deposition of a matrix into a preform having circumferentially wound ceramic fibers, comprises heating one surface of the preform while cooling the other surface thereof. The resulting product may have fibers that are wound on radial planes or at an angle from the radial planes. The fibers can also be precoated with pyrolytic carbon before application of the matrix. The matrix is applied by passing reactant gas through the preform thereof to the other side thereof for the initial deposition of matrix near such other surface of the preform. The matrix fills in the preform from the other side surface thereof to the surface of the side of application thereof until a desired amount of matrix has been deposited.

Abstract: A capillary for use in ball bonding tools designed to bond metal leads to the bonding pads on a microchip and pads or leads on a chip support is formed by chemically vapor depositing a substantially smooth silicon carbide coating having high electrical resistivity onto a substrate which is then removed by etching or combustion.

Abstract: A method of preparing carbon filaments which comprises exposing a suitable thermostable substrate which is covered with reduced monocrystalline metal particles with a diameter of at least 5 nanometers to a carbon containing gas mixture at temperatures of about 250.degree. up to about 700.degree. C. to 800.degree. C., for a period of time sufficient to form filaments of the desired length, and thereafter removing the substrate and/or the metal particles. The filaments are characterized by a crystalline graphitic structure and a morphology defined by a fishbone-like arrangement of the graphite layers along the axis of the filaments. A high carbide content is a prerequisite for the nucleation of the filamentous carbon with a fishbone like structure.

Abstract: A pyrolytic boron nitride article of the invention has uniform structure and has 0.5 or less nodules/cm.sup.2 in average all through the overall surface of the article and 2 or less nodules in any portion of the unit square centimeter on the surface of the article. The pyrolytic boron nitride article is produced by depositing boron nitride through a vapor phase, using a boron halide gas and an ammonia gas as the starting materials. Upon production, the ammonia gas or a gas mixture containing the ammonia gas is not contacted directly with graphite at 300.degree. to 1850.degree. C.

Abstract: Silicon and nitrogen ions are implanted in a ceramic body of silicon carbide and the ceramic body is heated in a nonoxidizing atmosphere, whereby it is reinforced.

Abstract: A transparent BN-type ceramic material comprising 10 to 40 wt. % of boron (B), 35 to 55 wt. % of nitrogen (N) and 3 to 40 wt. % of silicon (Si) as the main component elements, and 1 to 10 wt. % of sub-component elements, with the property of not being crystallized by heat treatment at 1600.degree. C. for one hour, and a method of producing the above ceramic material by reacting a boron-containing compound, a nitrogen-containing compound and a silicon-containing compound at deposition temperatures in a range of more than 1300.degree. C. to less than 1700.degree. C. with the total gas pressure within a reaction furnace maintained in the range from 10 Torr to 100 Torr by use of a chemical vapor deposition method are disclosed.

Abstract: A dome shaped ceramic vibration plate for an audio speaker is manufactured by vacuum evaporation and deposition using a laser beam. The vibration plate is formed as a thin ceramic film which adheres to the surface of a mother model, which is thereafter dissolved or fused away.

Abstract: Plastic resinous tubes, particularly for medical use is improved in blood compatibility when brought into contact with blood, by applying a low-temperature plasma treatment to inner surfaces of the tubes, which plasma is produced through electrodeless electric discharges by the effect of microwave to make it possible to prevent the tube from being heated in such a treatment. The inner surfaces of the tubes thus activated may be further subjected to an inner surface graft copolymerization treatment to enhance blood compatibility.

Abstract: According to the invention, the dipolar orientation of an object made of material adapted to present piezoelectric properties is obtained by exposing at least one of the faces of the object to a jet of charged microparticles in order to create therein a sufficient electrical field to obtain the said orientation, and in a variant of the invention, a direct polarization is carried out by displacing a film in front of at least one generator of charged microparticles, this invention applying in particular to the production of film in a piezoelectric polymer or copolymer.

Abstract: The invention provides a process for producing a piezo-electric or pyro-electric composite sheet in which particles of a piezo-electric or pyro-electric sintered body (ceramics) are dispersed in the form of a single layer in an insulating high polymeric substance, and the particles are in direct contact with electrodes made on both sides of the sheet. The composite sheet is produced by forming a sheet of an insulating high polymeric substance having dispersed therein particles of a piezo-electric or pyro-electric sintered body (ceramics) in the form of a single layer, then removing the surface skin from both sides of the sheet to expose the particles from both sides of the sheet; and making electrodes on both sides of the sheet and implying a voltage difference thereto to effect poling of the sheet.