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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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A technique involving superplastic processing and high-pressure autoclaving was applied to a nickel-base prealloyed powder alloy. Tensile strengths as high as 2865 MN/sq m (415 ksi) at 480 C (900 F) were obtained with as-superplastically deformed material. Appropriate treatments yielding materials with high-temperature tensile and stress-rupture strengths (980 C (1800 F)) were also devised.
Cleaning process reduces level of contaminants in superalloy end product. Procedure has applications to variety of powder metallurgy contamination problems.
A rapid and inexpensive method of obtaining processing-related data on powdered thermosetting resins has been investigated. The method involved viscosity measurements obtained with a small specimen (less than 100 mg) parallel plate plastometer. A data acquisition and reduction system was developed which provided a value of viscosity and strain rate about 12-13 second intervals during a test. The effects of specimen compaction pressure and reduction of adhesion between specimen and parallel plates were examined. The plastometer was used to measure some processing-related viscosity changes of an addition polyimide resin, including changes caused by pre-test heat treatment, test temperature, and strain rate.
The effects of heat-treatments on the microstructure of P/M Rene 95 (a nickel-based powder metal), consolidated by the hot-isostatic pressing (HIP), were examined. The microstructure of as-HIP'd specimen was characterized by highly serrated grain boundaries. Mechanical tests and microstructural observations reveal that the serrated grain boundaries improved ductility at both room and elevated temperatures by retarding crack propagation along grain boundaries.
Dense high-purity silicon aluminum oxynitride was prepared by reactive hot-pressing of an Si3N4-Al2O3-SiO2 mixture. The formation of a single-phase material was found to be critically dependent on the Si3N4 powder in the starting mixture. It is suggested that evolution of a chlorine- and nitrogen-containing species may enhance the reactivity of Si3N4 in this reaction. Densities of O prime sialons are very similar to that of Si2N2O, the widely quoted value in the ceramics literature of 3.1 g/cu cm for the density of Si2N2O being incorrect.
Following the original idea of Peters, techniques have been developed to fabricate large area powder silica counters with refractive index between 1.06 to 1.12 in thicknesses of 1 cm and 2 cm respectively. The maximum size counter is 25 cm x 25 cm but the technique can be easily extended to 40 cm x 30 cm counters. Techniques have also been developed to dope this counter with the wavelength shifter p-terphenyl uniformly. The results of test runs at the Brookhaven National Laboratory and of laboratory runs using a superconducting magnet spectrometer on their performance are reported.
Silicon powder is compacted by sandwiching it between two flat sheets scaled up for production, choice of metal making contact with silicon will be important, if high purity of silicon is to be preserved.
Radiometric and meteorological data acquired at three ground stations located approximately 150 km apart in the Powder River Basin, Wyoming, are summarized. The data were collected between July 10 and July 29, 1978, to support the HCMM thermal satellite data acquired during this time period. The parameters measured are direct solar radiance, total solar radiance, sky radiance, air temperature, relative humidity, wind speed, and wind direction. A tabulation of the measurement accuracies is presented.
The titanium dioxide surface is discussed. Polymer adhesive are also discussed. Titanium powders are considered. Characterization techniques are also considered. Interactions with polymers, water vapor, and HCl are reported. Adsorbents are characterized.
Developments of particulate metallurgy of alloyed materials where the final products is a fully dense body are discussed. Particulates are defined as powders, flakes, foils, silvers, ribbons and strip. Because rapid solidification is an important factor in particulate metallurgy, all of the particulates must have at least one dimension which is very fine, sometimes as fine as 10 to 50 microns, but move typically up to several hundred microns, provided that the dimension permits a minimum solidification rate of at least 100 K/s.
The formation of pyrrone resins of the ladder or semiladder structure is described. The technique involves initial formation of fully cyclized prepolymers having an average degree of polymerization of about 1.5, one with acidic terminal groups, another with amine terminal groups. Thereafter the prepolymers are intimately admixed on a 1:1 stoichiometric basis. The resulting powder mixture is molded at elevated pressures and temperatures to form a fully cyclized resin.
The characteristics of reflectance spectra are being used as a basis in investigations to infer the composition of planetary surfaces. However, the reflectance spectra of powdered materials depend not only on the composition of these materials, but also on other variables. A description is presented of the results of an exploratory series of measurements designed to investigate the importance of scattering geometry as a variable in determining the shapes of spectral reflectance curves, taking into account half a dozen materials of planetary interest. It is noted that the considered results are consistent with those reported by Adams and Felice (1967), especially the results on the variation with phase angle of the Red/Blue color ratio for various silicate materials. The measurements demonstrate in detail that scattering geometry does affect the shapes of spectral reflectance curve. In some cases this effect is quite significant.
A program aimed at the development of advanced powder-metallurgy (PM) aluminum alloys for high-temperature applications up to 650 F using the concepts of rapid solidification and mechanical alloying is discussed. In particular, application of rapidly solidified PM aluminum alloys to centrifugal compressor impellers, currently used in auxiliary power units for both military and commercial aircraft and potentially for advanced automotive gas turbine engines, is examined. It is shown that substitution of high-temperature aluminum for titanium alloy impellers operating in the 360-650 F range provides significant savings in material and machining costs and results in reduced component weight, and consequently, reduced rotating group inertia requirements.
Metal grains to be sintered precoated with frit metal. Coated metal powders used to make ink-like electrode pastes for printing and sintering electrode-fabrication process. Grains of base metal coated with lowmelting-point--, lead or tin-- by electroless deposition.
Research was conducted on reinforcing nickel based matrices with alumina trichites by using powder metallurgy. Alumina trichites previously coated with nickel are magnetically aligned. The felt obtained is then sintered under a light pressure at a temperature just below the melting point of nickel. The halogenated atmosphere technique makes it possible to incorporate a large number of additive elements such as chromium, titanium, zirconium, tantalum, niobium, aluminum, etc. It does not appear that going from laboratory scale to a semi-industrial scale in production would create any major problems.
A method for purifying ceramic powder for electronic parts is described. Impurities can be easily removed by this method. Alkaline metals are removed from ceramic power for electronic parts.
A plasticity theory has been developed to predict the mechanical response of powder metals during hot isostatic pressing. The theory parameters were obtained through an experimental program consisting of hydrostatic pressure tests, uniaxial compression and uniaxial tension tests. A nonlinear finite element code was modified to include the theory and the results of themodified code compared favorably to the results from a verification experiment.
Sustained arc plasma chemical reactor fabricates very-fine-grained inorganic solids having low thermal conductivity. Powder fabrication method, based on plasma tube technique produces pure solids without contamination commonly produced by grinding.