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Microwave sintering of nanophase ceramics without concomitant grain growth (open access)

Microwave sintering of nanophase ceramics without concomitant grain growth

A method of sintering nanocrystalline material is disclosed wherein the nanocrystalline material is microwaved to heat the material to a temperature less than about 70% of the melting point of the nanocrystalline material expressed in degrees K. This method produces sintered nanocrystalline material having a density greater than about 95% of theoretical and an average grain size not more than about 3 times the average grain size of the nanocrystalline material before sintering. Rutile TiO[sub 2] as well as various other ceramics have been prepared. Grain growth of as little as 1.67 times has resulted with densities of about 90% of theoretical.
Date: April 15, 1991
Creator: Eastman, J.A.; Sickafus, K.E. & Katz, J.D.
System: The UNT Digital Library
Cavity resonance absorption in ultra-high bandwidth CRT deflection structure (open access)

Cavity resonance absorption in ultra-high bandwidth CRT deflection structure

An improved ultra-high bandwidth helical coil deflection structure for a cathode ray tube is described comprising a first metal member having a bore therein, the metal walls of which form a first ground plane; a second metal member coaxially mounted in the bore of the first metal member and forming a second ground plane; a helical deflection coil coaxially mounted within the bore between the two ground planes; and a resistive load disposed in one end of the bore and electrically connected to the first and second ground planes, the resistive load having an impedance substantially equal to the characteristic impedance of the coaxial line formed by the two coaxial ground planes to inhibit cavity resonance in the structure within the ultra-high bandwidth of operation. Preferably, the resistive load comprises a carbon film on a surface of an end plug in one end of the bore.
Date: May 15, 1991
Creator: Dunham, M. E. & Hudson, C. L.
System: The UNT Digital Library
Microwave Sintering of Nanophase Ceramics Without Concomitant Grain Growth (open access)

Microwave Sintering of Nanophase Ceramics Without Concomitant Grain Growth

A method of sintering nanocrystalline material is disclosed wherein the nanocrystalline material is microwaved to heat the material to a temperature less than about 70% of the melting point of the nanocrystalline material expressed in degrees K. This method produces sintered nanocrystalline material having a density greater than about 95% of theoretical and an average grain size not more than about 3 times the average grain size of the nanocrystalline material before sintering. Rutile TiO{sub 2} as well as various other ceramics have been prepared. Grain growth of as little as 1.67 times has resulted with densities of about 90% of theoretical.
Date: April 15, 1991
Creator: Eastman, Jeffrey A.; Sickafus, Kurt E. & Katz, Joel D.
System: The UNT Digital Library
Catalysts for Conversion of Methane to Higher Hydrocarbons (open access)

Catalysts for Conversion of Methane to Higher Hydrocarbons

Catalysts for converting methane to higher hydrocarbons such as ethane and ethylene in the presence of oxygen at temperatures in the range of about 700 to 900{degrees}C are described. These catalysts comprise calcium oxide or gadolinium oxide respectively promoted with about 0.025--0.4 mole and about 0.1--0.7 mole sodium pyrophosphate. A preferred reaction temperature in a range of about 800 to 850{degrees}C with a preferred oxygen-to-methane ratio of about 2:1 provides an essentially constant C{sub 2} hydrocarbon yield in the range of about 12 to 19 percent over a period of time greater than about 20 hours.
Date: May 15, 1991
Creator: Siriwardane, Ranjani V.
System: The UNT Digital Library
Apparatus and method for critical current measurements (open access)

Apparatus and method for critical current measurements

An apparatus for the measurement of the critical current of a superconductive sample, e.g., a clad superconductive sample, the apparatus including a conductive coil, a means for maintaining the coil in proximity to a superconductive sample, an electrical connection means for passing a low amplitude alternating current through the coil, a cooling means for maintaining the superconductive sample at a preselected temperature, a means for passing a current through the superconductive sample, and, a means for monitoring reactance of the coil. The alternating current capable of generating a magnetic field sufficient to penetrate, e.g., any cladding, and to induce eddy currents in the superconductive material, passing a steadily increasing current through the superconductive material, the current characterized as having a different frequency than the alternating current, and, monitoring the reactance of the coil with a phase sensitive detector as the current passed through the superconductive material is steadily increased whereby critical current of the superconductive material can be observed as the point whereat a component of impedance deviates.
Date: March 15, 1991
Creator: Martin, J. A. & Dye, R. C.
System: The UNT Digital Library