SEARCH · Engineering Papers
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Crucible from a mixture of a beryllium oxide aggregate and hydraulic refractory cement, and coated with an impervious refractory oxide will not deteriorate in the presence of fused salt- molten metal mixtures such as uranium- magnesium-zinc-halide salt systems. Vessels cast by this process are used in the flux reduction of oxides of thorium and uranium.
Metal knee hinge with an adjustable sleeve worn on the outside of a leg cast facilitates movement of the knee joint. This helps eliminate stiffness of the knee and eliminates bulkiness and adjustment difficulty.
High strength aluminum casting alloys reinforced with whiskers
Aerospace castings from light ternary Mg-Li-Si alloy, discussing fabrication development
Shaping of precipitation hardened stainless steels by casting and powder metallurgy
Sphere forming and composite casting manufacturing experiments for AAP Orbital Workshop
Improving cast nickel-chromium alloys by addition of reactive metals
High toughness aluminum sand casting alloy for cryogenic applications
Monolithic precision castings using photoetched plastic and lost-wax investment techniques
Patterns with small lettering and intricate designs are prepared by using two-dimensional artwork, photographic reduction and Dycril. Two-dimensional artwork and photographic processes replace conventional relief work. Artwork size is convenient and does not restrict lettering and design size in casting.
Wind tunnel models are cast around core consisting of array of tubing. Principal advantage of technique is that greater number of pressure orifices are easily installed, without compromising aerodynamic shape of model. Technique reduces construction cost by about 50 percent.
Freeze casting of metal ceramic and refractory compound powders into plastic slips
Hydraulic apparatus for casting and molding of liquid polymers
Nickel plating onto etched aluminum castings
Composition, properties, and applications of superalloys and techniques for vacuum melting and vacuum casting procedures
This program assisted in the design and implementation of the composite casting demonstration for the Apollo 14 mission. Both flight and control samples were evaluated. Some conclusions resulting from a comparison of the flight and control samples were: (1) Solidification in neither the flight nor control samples was truly directional. (2) Apparent intermittent contact of the melt with the container in the flight samples led to unusual nucleation and growth structures. (3) There was greater uniformity, on a macro scale, of both pores and structural features in the flight sample; presumably the result of the reduced gravity conditions. (4) It seems quite feasible to produce enhanced dispersions of gases and dense phases in a melt which is solidified in reduced gravity. (5) A two-stage heating/cooling cycle may help directional solidification. (6) Sample materials should be selected from materials in which the dispersant fully wets the matrix material. (7) Experiments should be conducted in two modes: (1) where the melt is in good thermal contact with the container, and (2) where the melt is in a free-float condition.
Flight and control specimens 6, 9, and 12 from the Apollo 14 composite casting demonstration were evaluated with respect to the degree of dispersion achieved for mixtures of immiscible materials under one-gravity and low gravity environments. The flight and control capsules 6, 9, and 12 contained paraffin and sodium acetate; paraffin, sodium acetate and argon; and paraffin, sodium acetate and 100 micrometer diameter tungsten microspheres, respectively. The evaluation and documentation utilized photographic and microstructure examinations, density measurements, and droplet size and distribution determinations. In addition, theoretical analyses were performed in order to aid in the understanding of the fluid behavior of the specimens during processing and subsequent solidification. A comparison of evaluated data with the theoretical analyses reveals that although the immiscible materials were uniquely dispersed in a low gravity environment, nonuniform dispersions were obtained primarily due to insufficient initial mixing and an essentially unidirectional thermal gradient during cooldown.
The results of experiments 1, 2, and 10 of the Apollo 14 composite casting demonstration are discussed. The purpose of the demonstration, with regard to samples 1 and 2, was to obtain preliminary data on the liquid phase sintering process in a weightless environment. With regard to sample 10, the purpose was to obtain preliminary information on how to achieve uniform dispersion of dense particles on a metal matrix by employing shaking modes or forces in the system when the metal matrix is molten. Results of the demonstrations were interpreted in a quantitative and qualitative manner. For experiment 1 it was found that the tungsten particles were redistributed more uniformly in the flight sample than in the control sample. Experiment 2 results indicate that complete melting may not have occured and thus a high degree of significance cannot be associated with the qualitative results relating to particle redistribution data. The particle-matrix system of experiment 10 was found to be nonwetting.