Abstract: Arc metal spraying is used to spray liquid metal onto an array of high strength fibers that have been previously wound onto a large drum contained inside a controlled atmosphere chamber. This chamber is first evacuated to remove gaseous contaminants and then backfilled with a neutral gas up to atmospheric pressure. This process is used to produce a large size metal matrix composite monotape.

Abstract: An object of the invention is to provide variable damping for resonant vibrations which may occur at different rotational speeds in the range of rpms in which a rotating machine is operated.A variable force damper in accordance with the invention includes a rotating mass (12) carried on a shaft (11) which is supported by a bearing (13) in a resilient cage (14). Cage (14) is attached to a support plate (15) whose rim extends into an annular groove in a housing (17).Variable damping is effected by tabs (18) of electrically conducting, non-magnetic material which extend radially from the cage (14). The tabs (18) at an index position lie between the pole faces of respective C-shaped magnets (19). The magnets (19) are attached by cantilever spring members (20) to the housing (17).By rotating the support plate (15) about the axis of shaft (11), the tabs (18) may be rotated through an angle 0 of about 40.degree. away from the index or 0.degree. position. At the 40.degree. position minimum damping is obtained.

Abstract: Polyimide resins suitable for use as composite matrix materials are formed by copolymerization of maleic and norbornenyl endcapped monomers and oligomers. The copolymers can be cured at temperatures under about 300.degree. C. by controlling the available concentration of the maleic end-capped reactant. This control can be achieved by adding sufficient amounts of said maleic reactant, or by chemical modification of either copolymer, so as to either increase Diels-Alder retrogression of the norbornenyl capped reactant and/or holding initiation and polymerization to a rate compatible with the availability of the maleic-capped reactant.

Abstract: This invention is directed to transferring heat from an extremely high temperature source to an electrically isolated lower temperature receiver. The invention is particularly concerned with supplying thermal power to a thermionic converter from a nuclear reactor with electric isolation.Heat from a high temperature heat pipe (10) is transferred through a vacuum or a gap filled with electrically nonconducting gas (26) to a cooler heat pipe (18). The heat pipe (10) is used to cool the nuclear reactor while the heat pipe (18) is connected thermally and electrically to a thermionic converter (22).If the receiver requires greater thermal power density, geometries are used with larger heat pipe areas for transmitting and receiving energy than the area for conducting the heat to the thermionic converter. In this way the heat pipe capability for increasing thermal power densities compensates for the comparatively low thermal power densities through the electrically non-conducting gap between the two heat pipes.

Abstract: A battery separator for an alkaline battery. The separator comprises a cross-linked copolymer of vinyl alcohol units and unsaturated carboxylic acid units. The cross-linked copolymer is insoluble in water, has excellent zincate diffusion and oxygen gas barrier properties and a low electrical resistivity. Cross-linking with a polyaldehyde cross-linking agent is preferred.

Abstract: Polyimide resins suitable for use as composite matrix materials are formed by copolymerization of maleic and norbornenyl endcapped monomers and oligomers. The copolymers can be cured at temperatures under about 300.degree. C. by controlling the available concentration of the maleic end-capped reactant. This control can be achieved by adding sufficient amounts of said maleic reactant, or by chemical modification of either copolymer, so as to either increase Diels-Alder retrogression of the norbornenyl capped reactant and/or holding initiation and polymerization to a rate compatible with the availability of the maleic-capped reactant.

Abstract: Polyimide resins suitable for use as composite matrix materials are formed by copolymerization of maleic and norbornenyl endcapped monomers and oligomers. The copolymers can be cured at temperatures under about 300.degree. C. by controlling the available concentration of the maleic end-capped reactant. This control can be achieved by adding sufficient amounts of said maleic reactant, or by chemical modification of either copolymer, so as to either increase Diels-Alder retrogression of the norbornenyl capped reactant and/or holding initiation and polymerization to a rate compatible with the availability of the maleic-capped reactant.

Abstract: Polyimide resins suitable for use as composite matrix materials are formed by copolymerization of maleic and norbornenyl endcapped monomers and oligomers. The copolymers can be cured at temperatures under about 300.degree. C. by controlling the available concentration of the maleic end-capped reactant. This control can be achieved by adding sufficient amounts of said maleic reactant, or by chemical modification of either copolymer, so as to either increase Diels-Alder retrogression of the norbornenyl capped reactant and/or holding initiation and polymerization to a rate compatible with the availability of the maleic-capped reactant.

Abstract: A carbon coating (36) is vacuum arc deposited on a smooth surface of a target (10) which is simultaneously ion beam sputtered. The bombarding ions have sufficient energy to create diamond bonds. Spalling occurs as the carbon deposit thickens. The resulting diamondlike carbon flakes (26) have improved thermal, electrical, mechanical, and tribological properties when used in aerospace structures and components.

Abstract: Polyimide resins suitable for use as composite matrix materials are formed by copolymerization of maleic and norbornenyl end-capped monomers and oligomers. The copolymers can be cured at temperatures under about 300.degree. C. by controlling the available concentration of the maleic end-capped reactant. This control can be achieved by adding sufficient amounts of said maleic reactant, or by chemical modification of either copolymer, so as to either increase Diels-Alder retrogression of the norbornenyl-capped reactant and/or holding initiation and polymerization to a rate compatible with the availability of the maleic-capped reactant.

Abstract: A diamondlike carbon film is deposited in the surface of a substrate by exposing the surface to an argon ion beam containing a hydrocarbon. The current density in the ion beam is low during initial deposition of the film.Subsequent to this initial low current condition, the ion beam is increased to full power. At the same time a second argon ion beam is directed toward the surface of the substrate. The second ion beam has an energy level much greater than that of the ion beam containing the hydrocarbon. This addition of energy to the system increases mobility of the condensing atoms and serves to remove lesser bound atoms.

Abstract: This invention relates to a high temperature oxidation resistant thermal barrier coating system for a nickel-, cobalt-, or iron-base alloy substrate. An inner metal bond coating contacts the substrate, and a thermal barrier coating covers the bond coating.NiCrAlR, FeCrAlR, and CoCrAlR alloys have been satisfactory as bond coating compositions where R=Y or Yb. These alloys contain, by weight, 24.9-36.7% chromium, 5.4-18.5% aluminum, and 0.05 to 1.55% yttrium or 0.05 to 0.53% ytterbium. The coatings containing ytterbium are preferred over those containing yttrium.An outer thermal barrier coating of partially stabilized zirconium oxide (zirconia) which is between 6% and 8%, by weight, of yttrium oxide (yttria) covers the bond coating. Partial stabilization provides a material with superior durability. Partially stabilized zirconia consists of mixtures of cubic, tetragonal, and monoclinic phases.

Abstract: Sunlight is dispersed over a diffraction grating (12) formed on the surface of a conducting film (14) on a substrate (16). The angular dispersion controls the effective grating period so that a matching spectrum of surface plasmons (18) is excited for parallel processing on the conducting film. The resulting surface plasmons (18) carry energy to an array (20) of inelastic tunnel diodes. This solar energy converter does not require different materials for each frequency band, and sunlight is directly converted to electricity in an efficient manner by extracting more energy from the more energetic photons.

Abstract: Power is extracted from plasmons, photons, or other guided electromagnetic waves at infrared to mid-ultraviolet frequencies by inelastic tunneling in metal-insulator-semiconductor-metal diodes. Inelastic tunneling produces power by absorbing plasmons to pump electrons to higher potential. Specifically, an electron from a semiconductor layer absorbs a plasmon and simultaneously tunnels across an insulator into a metal layer which is at higher potential. The diode voltage determines the fraction of energy extracted from the plasmons; any excess is lost to heat.

Abstract: Interdigitated back contact solar cells are made by screen printing dopant materials onto the back surface of a semiconductor substrate in a pair of interdigitated patterns. These dopant materials are then diffused into the substrate to form junctions having configurations corresponding to these patterns. Contacts having configurations which match the patterns are then applied over the junctions.

Abstract: An improved ion thruster (10) for low specific impulse operation in the 1500 sec to 6000 sec range has a multicusp boundary field (48) provided by high strength magnets (30-38) on an iron anode shell (14) which lengthens the paths of electrons from a hollow cathode assembly (20). A downstream anode pole piece in the form of an iron ring (40) supports a ring of magnets (44) to provide a more uniform beam profile. A cylindrical cathode magnet (46) can be moved selectively in an axial direction along a feed tube (22) to produce the desired magnetic field at the cathode tip (24).

Abstract: A d-c to d-c converter which can start with a shorted output and which regulates output voltage and current is disclosed. Voltage controlled switches directed current through the primary of a transformer the secondary of which includes virtual reactance. The switching frequency of the switches is appropriately varied to increase the voltage drop across the virtual reactance in the secondary winding to which there is connected a low impedance load. A starting circuit suitable for voltage switching devices is provided.

Abstract: A ladder circuit especially useful in backward wave oscillators operating in the 500 GHz to 2,000 GHz range comprises a waveguide (10) having disposed therein transversely oriented slabs (16) which contact an upper wall (22) of waveguide (10). The edges of slabs (11) adjacent the physical center of waveguide (10) along which is directed an electron beam (19) have respective curved segments (11) and stubs (12) and (13) of electrically conductive, non-magnetic material supported thereon. The ends of slabs (16) include metal layers (17) and (18) at respective opposite ends to provide a conductive leakage path. A ridge bar (20) is attached to the inside of the bottom wall (21) of the waveguide (10) and includes a concave upper surface which partially straddles electron beam (19). The inside width of the waveguide (10) is approximately one-half wavelength as determined by the frequency of operation of the backward wave oscillator.

Abstract: Referring to FIG. 1, a method for making an improved electrode 15 having a gold coating 9 for use in the anode compartment 12 of a REDOX cell 10 is described. The anode fluid utilizes a chromic/chromous couple.The flow chart FIG. 2 illustrates the method wherein a carbon felt is soaked in methanol, rinsed in water, dried and then heated in KOH after which it is again washed in deionized water and dried.The felt is then moistened with a methanol-water solution containing chloroauric acid and is stored in a dark place while still in contact with the gold-containing solution.After all the gold-containing solution is absorbed by the felt, the latter is dried by heat and then heat-treated at a substantially greater temperature. The felt is now suitable for use as an electrode and is wetted with water or up to 2 molar HCl prior to installation in a REDOX cell.The two curves on the far right of FIG. 3 illustrate the low hydrogen evolution of the improved electrode.

Abstract: Polyimide resins suitable for use as composite matrix materials are formed by copolymerization of maleic and norbornenyl endcapped monomers and oligomers. The copolymers can be cured at temperatures under about 300.degree. C. by controlling the available concentration of the maleic end-capped reactant. This control can be achieved by adding sufficient amounts of said maleic reactant, or by chemical modification of either copolymer, so as to either increase Diels-Alder retrogression of the norbornenyl capped reactant and/or holding initiation and polymerization to a rate compatible with the availability of the maleic-capped reactant.