Abstract: A method for spheridizing silicon metal particles is described. The method involves injecting irregular silicon metal particles into a high-temperature plasma reactor to melt at least 50 weight percent of the particles. The molten droplets are solidified to form substantially spherical silicon particles having a thin SiO coating which may be removed by treating with a weak hydroxide solution.

Abstract: A method for producing fine or ultra fine powder particles comprising mixing a metal alkoxide with a non-metallic hydride in an organic solvent, agitating the mixed solution, and then burning the mixed solution. The burning process comprises igniting the solution directly or burning the solution in situ. A self-sustaining flame will result. When the precursor solution burns, the metallic compound will be co-fired with the organic solvent. As a result, fine or ultra fine particles of mixed metal will burst from the flame, or thrust through the flame and be synthesized.

Abstract: A fiber is formed by providing a stream of a solidifiable fluid, injecting the stream with a net charge so as to disrupt the stream and allowing the stream to solidify to form fibers.

Abstract: A versatile covering process enabled through the identification and manipulation of a plurality of variables present in the electrospinning method of the present invention. By manipulating and controlling various identified variables, it is possible to use electrospinning to predictably produce thin materials having desirable characteristics. The fibers created by the electrospinning process have diameters averaging less than 100 micrometers. Proper manipulation of the identified variables ensures that these fibers are still wet upon contacting a target surface, thereby adhering with each other to form a cloth-like material and, if desired, adhering to the target surface to form a covering thereon. The extremely small size of these fibers, and the resulting interstices therebetween, provides an effective vehicle for drug and radiation delivery, and forms an effective membrane for use in fuel cells.

Abstract: An apparatus and methods for electrospinning composite fibers comprising polymeric material and mesoporous molecular sieve material are described. The methods include in one aspect electrospinning fibers from a conducting solution to which a high voltage electric current is applied. The apparatus includes in one aspect one or more conducting solution introduction devices for providing a quantity of conducting solution, said conducting solution introduction devices being electrically charged thereby establishing an electric field between said conducting solution introduction devices and a target, and means for controlling the flow characteristics of conducting solution from said one or more conducting solution introduction devices.

Abstract: The present invention relates to a method for making shaped structures with internally coated cavities with an inside diameter in the nanometer to micrometer range and the shaped structure obtained thereby.

Abstract: An arrangement introduced into a balloon is capable to be applied in any inflated balloon having a traditional nozzle or mouthpiece, where the upper end of a flexible rod is fastened.

Abstract: A colored rotating granular body 21 has a surface color-coded in two different colors and electrification characteristics for each color and rotates by an effect of an electric field to display an associated color face. For producing the colored rotating granular bodies 21, a suspension 11 of granular bodies 1 each already in a colored state and functioning as a base and an emulsion 12 of a monomer 2 sill in an uncolored state are mixed, the monomer 2 is unevenly attached to a part of a surface of each of the granular bodies 1, the monomer attached to the granular bodies 1 are polymerized to obtain granular bodies 3 composed of the polymerized monomer, thereafter only the granular bodies 3 are selectively colored, and snowman-shaped complexed resin granular bodies 4 composed of the granular bodies 1 and the granular bodies 3 are integrally spheroidized.

Abstract: This invention is directed to a process for the rapid in-situ curing of polymerizable materials to provide macromolecular networks and articles of manufacture that are “morphology-trapped”; that is, they exhibit a fixed phase morphology and/or molecular orientation that is locked in by the curing step. The process includes the steps of mixing together a dead polymer, a reactive plasticizer and an initiator to give a polymerizable composition; further processing the mixture in order to achieve a desired phase morphology and/or molecular orientation of the polymeric constituents; shaping the polymerizable composition into a desired geometry; and exposing the polymerizable composition to a source of polymerizing energy, without mixing, to give a final product with the desired phase morphology and/or molecular orientation locked in place.

Abstract: An apparatus for fabricating bichromal elements comprising a separator member having a central rotating point, the separator member having first and second spaced apart, opposed surfaces with an edge region in contact with both of said opposed surfaces. The spacing between the opposed surfaces varies with the distance outwardly from the central rotating point such that the spacing is the largest at the central rotating point and the spacing decreases outwards from the central rotating point and the spacing is a minimum at the edge region. Further each of the opposed surfaces has a substantially annular cup spaced apart from and substantially surrounding the central rotating point.

Abstract: The invention relates to a method for capsulating microbial, plant and animal cells or biological and chemical substances, using a nozzle to obtain small, especially spherical particles by vibrating an immobilisation mixture. According to said method, the immobilisation mixture, especially a laminar fluid jet taking the form of an immobilisation mixture, is divided into equal parts by superimposition of an external vibration. In a device especially well suited to carry out this method a metallic counter-element (18) which is mounted down-stream from the nozzle (16) at a distance (a) to, and on the outside of, the nozzle axis (A) is connected to a high-voltage source (30). The counter-element is to be embodied by a metal ring (18) through whose through hole (20) the nozzle axis (A) extends. The metal ring (18) is radially connected to an insulated support (22, 24).

Abstract: A suspension, dispersion or emulsion is introduced into a burner. A two-stage after-treatment is then carried out. The resulting powder can be employed as a catalyst.

Abstract: A method of producing fibers comprises providing a stream of a solidifiable fluid, injecting the stream with a net charge so as to disrupt the stream and allowing the stream to solidify to form fibers. An apparatus for providing a stream of a solidifiable fluid is disclosed, as well as electrostatically formed fibers produced by the method.

Abstract: The present invention relates to a method for the rapid production of homogeneous, ultrafine inorganic material via liquid-phase reactions. The method of the present invention employs electrohydrodynamic flows in the vicinity of an electrified injector tube placed inside another tube to induce efficient turbulent mixing of two fluids containing reactive species. The rapid micromixing allows liquid-phase reactions to be conducted uniformly at high rates. This approach allows continuous production of non-agglomerated, monopispersed, submicron-sized, sphere-like powders.

Abstract: A suspension, dispersion or emulsion is introduced into a burner. A two-stage after-treatment is then carried out. The resulting powder can be employed as a catalyst.

Abstract: An apparatus and method of forming balls includes a metering device 2, a melting device 14 and a cooling device 20. The metering device 14 stamps a desired volume of solid material in the form of a slug 12 which passes through the melting device 14 where it is caused to levitate and transform state from a solid to a molten liquid. The molten liquid material 13 is released from the melting device 14 and descends through the cooling device 20 where it transforms state once again from a molten material to a solid material while maintaining a ball shape. A forming gas is passed over the molten material 13 in a direction opposite to the falling molten material 13. The balls 15 are finally cooled in a cooling bath 32.

Abstract: The present invention is a process and apparatus for producing nano-scale particles using the interaction between a laser beam and a liquid precursor solution. There are two embodiments. The first embodiment includes the use of a solid substrate during the laser-liquid interaction. In this embodiment the laser beam is directed at the solid substrate which is immersed in the liquid precursor solution and rotating. The second embodiment includes the use of a plasma during the laser-liquid interaction. In the second embodiment, a mixture of a liquid precursor and a carrier gas is injected into a laser beam. Injection of the mixture can be performed either perpendicular or parallel to the laser beam. The apparatus for injecting the liquid precursor and carrier gas into the laser beam includes a plasma nozzle designed to allow the laser beam to enter the plasma nozzle so that the laser beam may irradiate what is flowing through the plasma nozzle to create a plasma flow.

Abstract: An apparatus for fabricating bichromal balls includes a means for fabricating droplets from electrically conductive hardenable liquids. The liquids have different colors. A forward end of the hardenable liquids becomes unstable and breaks up into the droplets. Each droplet includes hemispheres of different colors. An RF signal generator produces electrical pulses which increase the instability of the forward end of the hardenable liquids. A capacitance in the conductive liquids causes current to flow from the signal generator to the hardenable liquids. A diameter of the droplets is reduced to form substantially spherical balls. Each of the balls includes hemispheres of different colors. The bichromal balls are collected.

Abstract: In the method proposed, microparticles suspended in a liquid or droplets suspended in a liquid with which they are immiscible are shaped by high-frequency electric fields in a three-dimensional electrode array of a size in the micrometer or submicrometer range and subsequently consolidated by prior art chemical bonding procedures or by physical methods. The disposition, geometry and control of the electrodes determine the shape of the particles. The particles themselves must have a conductivity and/or relative dielectric constant lower than the solution surrounding them. For some, this can be achieved only at certain frequencies in the kHz and MHz band which are determined by the passive electrical properties of the particles and the surrounding solution. The particles or droplets are repelled by the electrodes so that they are shaped in the free solution without making contact with any surface and can then be consolidated.

Abstract: A Pulse Detonation Synthesis (PDS) process for the manufacture and deposition of ceramic powders and coatings is disclosed. PDS may use multiple detonation pulses that are initiated in a reaction chamber to synthesize ceramic materials from reactants introduced into the chamber. The reactants may be provided in the form of divided solids, gases, liquids, gels, and/or mixtures of the foregoing. The synthesized ceramic materials may take the form of micron and/or nano-scale powders or coatings. Non-coating powders may be collected for later use. The coatings produced by the present invention include, but are not limited to, gradient coatings, uniform coatings, thermal barrier coatings, and other commercially useful coatings.

Abstract: The present invention is a process and apparatus for producing nano-scale particles using the interaction between a laser beam and a liquid precursor solution. There are two embodiments. The first embodiment includes the use of a solid substrate during the laser-liquid interaction. In this embodiment the laser beam is directed at the solid substrate which is immersed in the liquid precursor solution and rotating. The second embodiment includes the use of a plasma during the laser-liquid interaction. In the second embodiment, a mixture of a liquid precursor and a carrier gas is injected into a laser beam. Injection of the mixture can be performed either perpendicular or parallel to the laser beam. The apparatus for injecting the liquid precursor and carrier gas into the laser beam includes a plasma nozzle designed to allow the laser beam to enter the plasma nozzle so that the laser beam may irradiate what is flowing through the plasma nozzle to create a plasma flow.

Abstract: A process for vapor depositing an evaporant onto a substrate is provided which involves:presenting the substrate to a deposition chamber, wherein the deposition chamber has an operating pressure of from 0.001 Torr to atmospheric pressure and has coupled thereto a carrier gas stream generator and an electron beam gun capable of providing an electron beam at the operating pressure and contains an evaporant source;impinging the evaporant source with the electron beam to generate the evaporant;entraining the evaporant in the carrier gas stream; andcoating the substrate with the carrier gas stream which contains the entrained evaporant, and an apparatus for performing the process.

Abstract: A metal or an alloy thereof, or a ceramic that has a liquid phase is introduced in the form of a rod or a wire or as a liquid stream into the apex formed by a plurality of converging plasma jets. Atomization takes place and upon controlled cooling good quality spheroidal powders are obtained whose size varies generally between about 10 and 300 .mu.m.

Abstract: Method and apparatus for making nanoparticles of a material having a diameter of 100 nanometers or less wherein the material to be formed into nanoparticles is evaporated to form a vapor plume therein, a non-reactive entrainment gaseous atmosphere suitable for evaporation conditions is introduced to a first chamber, a gaseous jet is directed through the vapor plume in a direction to carry nanoparticles formed by quenching of the vapor plume through a flow restriction orifice between the first chamber and a second chamber downstream of the first chamber, recirculation of the gaseous jet and nanoparticles entrained therein from the second chamber to the first chamber is substantially prevented to thereby provide a second stage of the gaseous jet downstream of the orifice and substantially isolated from said first chamber for flow to the second chamber, and collecting the nanoparticles from the second stage of said gaseous jet in a collection chamber downstream from the orifice.

Abstract: Nanoparticles of a material less than about 100 nm in diameter are made by evaporating the material in an evaporation chamber residing in an entrainment chamber having a gaseous atmosphere therein. The evaporator is disposed in but isolated from the entrainment chamber, except for a gaseous jet discharge opening. A carrier gas is introduced to the evaporation chamber to carry vapor of the material in the evaporation chamber through the discharge opening into the entrainment chamber as a gaseous jet. The gaseous jet entrains the gaseous atmosphere for quenching the vapor to form nanoparticles. Solid material is supplied at a feedrate to a supply opening of the evaporation chamber, melted at an end region remote from the supply opening, and evaporated at the end region at an evaporation rate equal to the feed rate of the solid material.

Abstract: A method of synthesizing encapsulated nanocrystals inside protective shells is disclosed. This method produces nanocrystals of metals, alloys, and compounds which are individually encapsulated by protective graphite shells which completely separate the nanocrystals from the environment. A separation method is also disclosed which eliminates most of all other debris except the encapsulated nanocrystals from the preparation product.

Abstract: A method and apparatus for producing nanodrops which are liquid drops with diameters less than one micron and producing therefrom solid nanoparticles and uniform and patterned film deposits. A liquid precursor is placed in an open ended tube within which is a solid electrically conductive needle which protrudes beyond the open end of the tube. Surface tension of the liquid at the tube end prevents the liquid from flowing from the tube. Mutually repulsive electric charges are injected into the liquid through the needle, causing the surface tension to be overcome to produce a plurality of liquid jets which break up into nanodrops.

Abstract: A process for producing charged uniformly sized metal droplets in which a quantity of metal is placed in a container and liquified, the container having a plurality of orifices to permit passage of the liquified metal therethrough. The liquified metal is vibrated in the container. The vibrating liquified metal is forced through the orifices, the vibration causing the liquified metal to form uniformly sized metal droplets. A charge is placed on the liquified metal either when it is in the container or after the liquified metal exits the container, the charging thereof causing the droplets to maintain their uniform size. The uniformly sized droplets can be used to coat a substrate with the liquified metal.

Abstract: An apparatus for fabricating hemispherically bichromal balls, comprising a separator member having opposing first and second surfaces located and an edge region in contact with both surfaces, and delivery means for flowing first and second colored hardenable liquid material over the first and second surfaces, respectively, so that the liquid materials arrive at the edge at substantially the same flow rate and form a reservoir outboard of the edge region. The reservoir comprises side-by-side regions of different colors which do not intermix. Further means is provided for propelling the first and second liquid materials away from the separator member and out of the reservoir into a fluid medium as a plurality of side-by-side bichromal streams whose forward ends become unstable and break up into droplets which form into spherical balls, each of the balls comprising hemispheres of differently colored hardenable liquid, and means for collecting the bichromal balls.

Abstract: The present invention describes a method of explosively vaporizing a piece f semiconductor material in a plasma formed by a fast, high voltage current pulse. The semiconductor material may be formed from crystalline, polycrystalline, or amorphous forms of semiconductor material. After the semiconductor material is vaporized, it coalesces as the plasma begins to cool and is deposited in a collection system. The size and composition of the microparticles formed by this process can be controlled by conditioning the plasma in predetermined manners. In particular, impurities can be introduced either in the target material, in gas introduced in the plasma, or in the gas through which the coalescing microparticles travel prior to deposition.

Abstract: A process and apparatus are disclosed for producing polymerized beads containing actives such as perfumes and pesticides, by forming droplets from a solution of monomers and the actives. The solution is subjected to ultraviolet light to initiate polymerization. The droplets are caused to fall through a reaction vessel as polymerization continues so as to polymerize substantially spherical beads containing the actives. In one embodiment, the droplets are irradiated as they fall through the reaction vessel. In a second embodiment, the solution is irradiated prior to droplet formation and the fall. The beads are collected and can be cured if necessary. The process is preferably performed in an inert gas environment which most preferably is nitrogen. A nitrogen stream can serve as a carrier for the monomers and active ingredients. The nitrogen environment is maintained in the reaction vessel, and in the curing structure, if present.

Abstract: A novel process for rapid solidification of ceramic melts combines certain features of cooling by atomization and by contact with chilling surfaces. The material to be solidified is divided into fine liquid droplets that are propelled by a rapid flow of gas toward a rapidly moving chill surface, striking the surface with sufficient velocity to flatten each drop into a flat flake like shape. Apparatus for the process is also disclosed. The process is particularly applicable to making very fine grained, or even amorphous, ceramic materials that can be powdered and then sintered into strong, tough ceramic structures.

Abstract: Electrostatic spinning method for producing tubular fibrous structures from fiberizable material wherein the fiberizable material is collected on an electrostatically charged mandrel wherein the fiberizable material takes different paths from the source to the mandrel to produce a structure of smaller diameter fibers randomly oriented, larger diameter fibers and/or bundles of fibers circumferentially oriented and elongated voids circumferentially oriented.

Abstract: Uniform discoid particles made of at least one member selected from the group consisting of a natural high molecular substance, a synthetic high molecular substance and an inorganic compound, wherein each particle has a diameter of 20 to 2,000 .mu.m and a thickness/diameter ratio of 1/2 to 1/50, and not less than 80% of the whole particles have a diameter within the range of 0.5 to 2 times the number average diameter, and a process for preparing the particles. The discoid particle of the present invention has a larger surface area and therefore has a high efficiency when employed in various uses such as a parent material for an ion exchange resin, a packing material for a chromatograph, a catalyst and an culture medium for cell culture in comparison with conventional spherical particle.

Abstract: Monodisperse, polymeric microspheres are formed by injecting uniformly shaped droplets of radiation polymerizable monomers, preferably a biocompatible monomer, having covalent binding sites such as hydroxyethylmethacrylate, into a zone, impressing a like charge on the droplet so that they mutually repel each other, spheroidizing the droplets within the zone and collecting the droplets in a pool of cryogenic liquid. As the droplets enter the liquid, they freeze into solid, glassy microspheres, which vaporizes a portion of the cryogenic liquid to form a layer. The like-charged microspheres, suspended within the layer, move to the edge of the vessel holding the pool, are discharged, fall and are collected. The collected microspheres are irradiated while frozen in the cryogenic liquid to form latent free radicals. The frozen microspheres are then slowly thawed to activate the free radicals which polymerize the monomer to form evenly-sized, evenly-shaped, monodisperse polymeric microspheres.

Abstract: A plurality of holders, each capable of holding a rod of raw material, and a single handler are equipped within a chamber which is adapted to be evacuated. An operator positions one of the holders at a location where it is opposite to a rotary shaft capable of driving the rod of raw material for rotation at a high speed. The operator then secures the rod held by the holder to the free end of the rotary shaft by handling the holder. A rod of raw material which has become consumed by granulation is separated from the rotary shaft by the handler which is operated by the operator. A fresh holder is then positioned at a location where it is opposite to the rotary shaft, and a rod of raw material which is held thereby is then secured to the rotary shaft.

Abstract: Perfectly spherical, smooth and uniform microcapsules, which may contain living cells, are produced having a diameter less than 700 .mu.m by employing an electrostatic droplet generator. A droplet is suspended from a pointed source, such as a needle, and is charged with high static voltage. A collecting vessel or ring device is charged with opposing polarity and attracts the droplet. When a voltage potential threshold is passed, the droplet moves from the source to the collecting vessel. The voltage pulse height, pulse frequency and length, and extrusion rate of the droplets are adjustable so that predetermined sizes of droplets may be repeatedly generated and collected.

Abstract: Very small, individual polymeric microspheres with very precise size and a wide variation in monomer type and properties are produced by deploying a precisely formed liquid monomer droplet, suitably an acrylic compound such as hydroxyethyl methacrylate into a containerless environment. The droplet which assumes a spheroid shape is subjected to polymerizing radiation such as ultraviolet or gamma radiation as it travels through the environment. Polymeric microspheres having precise diameters varying no more than plus or minus 5 percent from an average size are recovered. Many types of fillers including magnetic fillers may be dispersed in the liquid droplet.

Abstract: A novel process for rapid solidification of ceramic melts combines certain features of cooling by atomization and by contact with chilling surfaces. The material to be solidified is divided into fine liquid dropletes that are propelled by a rapid flow of gas toward a rapidly moving chill surface, striking the surface with sufficient velocity to flatten each drop into a flat flake like shape. Apparatus for the process is also disclosed. The process is particularly applicable to making very fine grained, or even amorphous, ceramic materials that can be powdered and then sintered into strong, tough ceramic structures.

Abstract: A process for producing ultrafine particles of a ceramic, which comprises heating a ceramic having substantially the same components as the final ultrafine ceramic particles, a metal constituting the metal component of the final ultrafine ceramic particles, a mixture of said ceramic with said metal or carbon, or a mixture of said metal with carbon by an arc plasma or a high frequency induction plasma generated in hydrogen, nitrogen, oxygen, a gaseous mixture of hydrogen and nitrogen, or a gaseous mixture of nitrogen and oxygen.

Abstract: A method and apparatus for producing fine metal powder. The method includes the steps of forming a centrifugally maintained annulus of a liquified gas quench medium, forming molten metal drops within the eye of the annulus, urging the drops into the quench medium to solidify the drops, and boiling away the quench medium to leave behind clean, unentrained metal powder. The apparatus includes a drum for containing a liquified gas quench medium, means for adding liquified gas to the inside of the drum, and means for rotating the drum to form an annulus of quench medium. The apparatus further includes means for forming molten metal to be made into powder, and means disposed along the longitudinal axis of the drum and within the eye of the annulus for creating molten metal drops. The molten metal drops are then urged into the quench medium to solidify them into a powder, and the quench medium is boiled away to leave behind clean, unentrained metal powder.

Abstract: A method and apparatus for producing uniform, monosize ceramic particles forming the microsize particles by vapor condensation or ultrasonic cavitation. Organometallic liquids are directed to an aerosol generator where a droplet stream is projected in free flight within a reaction chamber and a particle sorter. Through the process of sorting the droplets according to their velocity in flight, monosize droplets are collected. The particles may be reacted prior to or after sorting and collection to form the monosize ceramic particle of interest. Sintering aids are introduced into the process to produce ceramic particles capable of improved green body formation.

Abstract: A process for the production of solid particles, characterized by the solidification in flight of an electrically charged spray of fluid droplets of narrow particle size distribution, and an apparatus for that process comprising a sprayhead with a channel for the fluid communicating with an outlet; means for subjecting the fluid to an electrical field such that the fluid will move from the sprayhead under the influence of the field to produce a spray of the fluid, the means including means for applying a first potential to the fluid; an electrode mounted spaced from but adjacent to the sprayhead with means to apply a second potential to that electrode; and a spray chamber, so positioned that in use the sprayhead delivers the spray to the chamber interior, and provided with means to apply a third potential to the chamber, and so dimensioned and arranged that in use the majority of the spray droplets solidify before impinging on any surface of or within the chamber.

Abstract: Electrostatic spraying apparatus and process for spraying liquids which form a coalescent resistant surface in flight in a particular environment to produce a powder or granular material. The process involves delivering a liquid to a spraying site of an electrostatic spray head; making contact with the liquid via an electrically conducting or semiconducting liquid contacting surface; charging the liquid contacting surface to a high voltage of one polarity relative to a reference surface to intensify the electric field strength at the spraying site sufficiently that the liquid at the spraying site is drawn out preponderantly by electrostatic forces into at least one cone from which a corresponding ligament issues and breaks up into a spray of electrostatically charged droplets; providing the environment in a space sufficient that droplets from the spray head form, in flight, particles having a substantially coalescent resistant surface; and collecting the particles so formed.

Abstract: A process for producing finely divided spherical copper copper alloy powders comprises forming an aqueous solution of copper and alternatively other metal values forming a reducible metallic material from the solution, reducing the material to metal powder particles, subjecting the metal particles to a high temperature zone to melt a portion of the metal powder particles and to form droplets and cooling the droplets to form an essential spherical metal alloy particles.

Abstract: A method is provided for producing commercially large quantities of high melting temperature solid or hollow spherical particles of a predetermined chemical composition and having a uniform and controlled size distribution. An end (18, 50, 90) of a solid or hollow rod (20, 48, 88) of the material is rendered molten by a laser beam (14, 44, 82). Because of this, there is no possibility of the molten rod material becoming contaminated with extraneous material. In various aspects of the invention, an electric field is applied to the molten rod end (18, 90), and/or the molten rod end (50, 90) is vibrated. In a further aspect of the invention, a high-frequency component is added to the electric field applied to the molten end of the rod (90).

Abstract: System and method for producing metal or alloy powder are described comprising an electromagnetic levitating coil having an outlet for supporting a molten source of the metal or alloy and controllably discharging a molten stream thereof, an electromagnetic confining coil disposed at the outlet of the levitating coil and surrounding the molten stream for controlling the diameter of the molten stream, and either an atomization die and associated pressurized fluid source for disintergrating the confined molten stream into molten droplets for subsequent cooling to powder, or a controllable electromagnetic coil surrounding the confined molten stream for generating a downwardly and radially outwardly directed electromagnetic force interacting with the molten stream to form the droplets.

Abstract: A process for producing ultrafine particles includes the steps of providing a consumable electrode having a rod or wire configuration, melting the tip of the electrode by means of electron bombardment, and applying an intense electric field to the molten tip to generate a beam of charged droplets. By heating the tip of the rod but avoiding melting of the tip and subsequently applying an electric field to the heated tip, an ion beam may be generated.

Abstract: Apparatus is provided for the production of ultrafine powder. The powder is produced by spark erosion within an electric discharge cell. The starting material for production of the powder is a body in chunk form of the material to be pulverized. The material is contained in an electric discharge cell having a fine mesh screen bottom. The cell and its contents are immersed in a dielectric fluid such as water, liquified gas or an organic base liquid. The cell and its contents are vibrated to cause the chunks to separate repeatedly and momentarily. A sparking voltage is impressed repeatedly through the body to develop sparks between confronting portions of separated chunk surfaces. Small particles produced as a result of the sparking fall through the screen of the cell and are collected as product.

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.