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Shelf life aging of DC-302 silicone molding compound

Description: DC-302 silicone molding compound (Dow Corning Corporation) was packaged 10 different ways, stored at three different temperatures, and tested for spiral flow periodically for 8 months. The material was very stable at 5/sup 0/C and fairly stable at 24/sup 0/C. It was sensitive to heat, however, and was unstable at 55/sup 0/C. Samples that were stored for 12 months at 5/sup 0/C showed no significant change in physical properties.
Date: August 1, 1978
Creator: McFarland, J. W.
Partner: UNT Libraries Government Documents Department

Solution hardening and strain hardening at elevated temperatures

Description: Solutes can significantly increase the rate of strain hardening; as a consequence, the saturation stress, at which strain hardening tends to cease for a given temperature and strain rate, is increased more than the yield stress: this is the major effect of solutes on strength at elevated temperatures, especially in the regime where dynamic strain-aging occurs. It is shown that local solute mobility can affect both the rate of dynamic recovery and the dislocation/dislocation interaction strength. The latter effect leads to multiplicative solution strengthening. It is explained by a new model based on repeated dislocation unlocking, in a high-temperature limit, which also rationalizes the stress dependence of static and dynamic strain-aging, and may help explain the plateau of the yield stress at elevated temperatures. 15 figures.
Date: October 1, 1982
Creator: Kocks, U.F.
Partner: UNT Libraries Government Documents Department

Tensile properties of bare-rolled ingot-sheet beryllium from room temperature to 800$sup 0$C

Description: Tensile properties of bare-rolled ingot-sheet beryllium from room temperature to 800 deg C are reported. While strength values show a steady decrease above room temperature, tensile elongations exhibit peaks at approximately 300 and 700 deg C. The strainhardening exponent varies with temperature and amount of strain, and ranges between approximately 0.10 and 0.26. Metallographic examinations reveal cleavage fracture at the lower temperatures, accompanied by severe grain deformation above room temperature. This is followed by a temperature range in which ductile rupture occurs, and finally, at the higher temperatures, grainboundary failure. The low BeO content of this material and the post-rolling heat treatment given to the sheet are factors which improve the high-temperature ductility as compared to other grades of beryllium. (auth)
Date: December 13, 1973
Creator: Miley, D.V. & Brugger, R.P.
Partner: UNT Libraries Government Documents Department

Conversion of para to orthohydrogen in a gamma-ray and neutron radiation field

Description: The radiation-induced conversion of para to orthohydrogen was investigated at pressures between 150 and 2200 psig (1 to 15 x 10/sup 6/ N/meter/ sup 2/) at three temperatures: 77 deg K (LN/sub 2/), 200 deg K (dry ice), and 300 deg K (ambient). Two radiation dose levels were studied: gamma rays only at 8 x 10/sup 6/ rads and a combination of 5 x 10/sup 14/ n/cm/sup 2/ E> 1 MeV, plus gamma rays at 8 x 10/sup 5/ rads. The conversion at LN/sub 2/ temperature was nearly zero in all cases. (auth)
Date: November 1, 1973
Creator: Conant, J.W.; Edeskuty, F.J.; Huston, J.E. & Thome, F.V.
Partner: UNT Libraries Government Documents Department

Comparison of elementary geothermal-brine power-production processes

Description: From applied technology geothermal committee meeting; Idaho Falls, Idaho, USA (7 Aug 1973). A comparison of three simple geothermal power- production systems shows that the flashed steam and the compound systems are favored for use with high-temperature brines. The binary system becomes economically competitive only when used on low-temperature brines (enthalpies less than 350 Btu/lb). Geothermal power appears to be economically attractive even when low-temperature brines are used. (auth)
Date: August 1, 1973
Creator: Green, M.A. & Laird, A.D.K.
Partner: UNT Libraries Government Documents Department