Preparation of fibered ceramics by mechanical deformation
Preparation of ceramic fibers by extrusion in metal matrix
Jech, R. W.↗
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Production of oxide fibers by co-reduction Final report
Plastic deformation of metal oxides by high temperature extrusion in molybdenum and tungsten
Loewenstein, P.↗
Fibering of ceramics by mechanical deformation
Ceramic fibers formation by particles mechanical deformation by extrusion in W matrix, describing grain structure of various extruded metal oxides
Jech, R. W.↗
Fibering ceramics by mechanical deformation
Ceramic fibers formation by particles mechanical deformation by extrusion in W matrix, describing grain structure of various extruded metal oxides
Jech, R. W.↗
Apollo 12 spinels as petrogenetic indicators
Lunar 12 spinel compositional variation and textures as petrogenetic indicators, showing magma differentiation by crystal settling after lunar surface extrusion
Reid, J. B., Jr.↗
Field evaporation ion source with possible application to electrostatic propulsion
Field evaporation of solid metal electrodes has been proposed as an ion source for an electrostatic propulsion device. The chief advantage over existing ion sources is the prospect of 100 percent fuel utilization efficiency. This advantage arises as a result of the elimination of the need for a gaseous precursor state for propellant ionization. The attainment of required high surface field strengths is achieved through field-induced extrusion of the electrode geometry at elevated temperatures. Contributions of both surface and bulk transport mechanisms are taken into account.
Weizer, V. G.↗
Development of superalloys by powder metallurgy for use at 1000 - 1400 F
Consolidated powders of four nickel-base superalloys were studied for potential application as compressor and turbine discs in jet engines. All of the alloys were based on the Rene' 95 chemistry. Three of these had variations in carbon and A12O3 contents, and the fourth alloy was chemically modified to a higher volume fraction. The A12O3 was added by preoxidation of the powders prior to extrusion. Various levels of four experimental factors (1) alloy composition, (2) grain size, (3) thermomechanical processing, and (4) room temperature deformation plus final age were evaluated by tensile and stress rupture testing at 1200 F. Various levels of the four factors were assumed in order to construct the statistically-designed experiment, but the actual levels investigated were established in preliminary studies that preceded the statistical process development study.
Calhoun, C. D.↗
The viscosity of magmatic silicate liquids: A model for calculation
A simple model has been designed to allow reasonably accurate calculations of viscosity as a function of temperature and composition. The problem of predicting viscosities of anhydrous silicate liquids has been investigated since such viscosity numbers are applicable to many extrusive melts and to nearly dry magmatic liquids in general. The fluidizing action of water dissolved in silicate melts is well recognized and it is now possible to predict the effect of water content on viscosity in a semiquantitative way. Water was not incorporated directly into the model. Viscosities of anhydrous compositions were calculated, and, where necessary, the effect of added water and estimated. The model can be easily modified to incorporate the effect of water whenever sufficient additional data are accumulated.
Bottinga, Y.↗
Solid propellant processing factor in rocket motor design
The ways are described by which propellant processing is affected by choices made in designing rocket engines. Tradeoff studies, design proof or scaleup studies, and special design features are presented that are required to obtain high product quality, and optimum processing costs. Processing is considered to include the operational steps involved with the lining and preparation of the motor case for the grain; the procurement of propellant raw materials; and propellant mixing, casting or extrusion, curing, machining, and finishing. The design criteria, recommended practices, and propellant formulations are included.
Source record↗
Boron epoxy reinforced structural sections.
A NASA Research program on the development of lightweight aluminum stiffening sections will be reviewed. The sections under investigation are hollowed extrusions which have been reinforced with boron epoxy by means of a fiber infiltration scheme being developed by Avco. Advantages of this type of construction are cost, environmental stability, manufacturing flexibility, and simplicity in joining. Present studies are focused on developing and verifying structural concepts for stiffener sections for compression panels. Results of analytical studies to size boron reinforcement will be discussed. Compression test results on stiffener sections will be presented and the design of a large compression panel will be reviewed. Results from compression panel efficiency studies indicate that panels with infiltrated stiffeners may be as much as 25% lighter than comparable all aluminum panels.-
Roy, P. A.↗
Powder-metallurgy superalloy strengthened by a secondary gamma phase.
Description of experiments in which prealloyed powders of superalloy compositions were consolidated by extrusion after the strengthening by precipitation of a body-centered tetragonal gamma secondary Ni3 Ta phase. Thin foil electron microscopy showed that the mechanical properties of the resultant powder-metallurgy product were correlated with its microstructure. The product exhibited high strength at 1200 F without loss of ductility, after thermomechanical treatment and aging.
Kotval, P. S.↗
The Apollo 15 lunar samples - A preliminary description.
Samples returned from the Apollo 15 site consist of mare basalts and breccias with a variety of premare igneous rocks. The mare basalts are from at least two different lava flows. The bulk chemical compositions and textures of these rocks confirm the previous conclusion that the lunar maria consist of a series of extrusive volcanic rocks that are rich in iron and poor in sodium. The breccias contain abundant clasts of anorthositic fragments along with clasts of basaltic rocks much richer in plagioclase than the mare basalts. These two rock types also occur as common components in soil samples from this site. The rocks and soils from both the front and mare region exhibit a variety of shock characteristics that can best be ascribed to ray material from the craters Aristillus or Autolycus.
Source record↗
U-Th-Pb systematics in three Apollo 14 basalts and the problem of initial Pb in lunar rocks.
The isotopic composition of Pb and the elemental concentration of U, Th and Pb were measured on 'total' rock samples 14053, 14073 and 14310 and on mineral separates of 14310 and 14053. These are the first Pb-U isochrons obtained for lunar basalts and indicate a reasonable solution to the previous discrepancy between the different methods of 'absolute' age determination. The resulting U-Pb isochron ages are compatible with the Rb-Sr and K-Ar ages on the same rocks. However, it is not possible to establish a precise time of 'crystallization' from the Pb-U data because of the small angle of intersection between the linear arrays and the concordia curve. These data show that total rock model ages do not in general yield crystallization ages. The data on 14310 and 14053 show that these rocks were formed containing a highly radiogenic initial lead which accounts for the excessively high total rock model ages by the U-Th-Pb method. The data prove that at the time of extrusion of some basalts, unsupported lead with extremely high Pb-207/Pb-206 ratios was added to the lunar surface.
Tera, F.↗
Autoclave heat treatment for prealloyed powder products
Technique could be applied directly to loose powders as part of hot pressing process of forming them to any required shapes. This would eliminate initial extrusion step commonly applied to prealloyed powders, substantially reduce cost of forming operation, and result in optimum properties.
Freche, J. C.↗
Development of a Power Metallurgy Superalloy for Use at 1800-2000 F (980-1090 C)
A program was conducted to develop a powder metallurgy nickel-base superalloy for 1800-2000 F (980-1090 C) temperature applications. The feasibility of a unique concept for alloying carbon into a superalloy powder matrix and achieving both grain growth and a discrete particle grain boundary carbide precipitation was demonstrated. The process consisted of blending metastable carbides with a carbon free base alloy and consolidating this blend by hot extrusion. This was followed by heat treatment to grow a desired ASTM No. 2-3 grain size and to solution the metastable carbides to allow precipitation of discrete particle grain boundary carbides during subsequent aging heat treatments. The best alloy developed during this program was hydrogen-atomized, thermal-mechanically processed, modified MAR-M246 base alloy plus VC (0.28 w/o C). Although below those for cast MAR-M246, the mechanical properties exhibited by this alloy represent the best combination offered by conventional powder metallurgy processing to date.
Kortovich, C. S.↗
The Alhazen to Abul Wafa swirl belt: An extensive field of light colored, sinuous markings, part T
Problematic causes and characteristics of light colored sinuous markings on the lunar surface are explored. Two processes, exogenetic and endogenetic, are examined in detailed. During the endogenetic process it is suggested that impact ejecta deposition and surface disturbances cause the markings. During the endogenetic process, it is suggested that extrusive volcanism and sublimation and/or alteration cause the markings.
El-Baz, F.↗
Apollo 14 mineral ages and the thermal history of the Fra Mauro formation.
The thermal inertia of the Fra Mauro formation limits its rate of cooling. The calculations of Jaeger (1961) for the cooling of an extrusive sheet are used to estimate the time required for a central temperature drop of 10%. This time is found to be about 45 years. For a 90% temperature drop, the time is about 200 years. Analytical methods used in the investigations are discussed together with the diffusion of Rb and Sr within lunar basalt. Isochron diagrams for various minerals are presented.
Compston, W.↗
Identification, distribution and significance of lunar volcanic domes.
Over 300 previously unrecognized volcanic domes were identified on Lunar Orbiter photographs using the following criteria: (1) the recognition of land forms on the Moon similar in morphology to terrestrial volcanic domes, (2) structural control, (3) geomorphic discordance, and (4) the recognition of land forms modified by dome-like swellings. Many terrestrial volcanic domes are similar in morphology to lunar domes. This analogy suggests that some lunar hills are in fact extrusive volcanic domes. Many of the domes identified in this paper seem to be related to basins and craters, and with the exception of local tectonic grid control few domes are related to any observable Moon-wide pattern.
Smith, E. I.↗