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METHOD OF IMPROVING IMPACT RESISTANCE
OF CERAMIC BODIES, AND IMPROVED BODIES

NASA Case No. LEW-12301

Canada, France, Great Britain,
Japan, Sweden, West Germany

Address inquiries to:

Lewis Research Center
Attn: Patent Counsel
Mail Code: 500-113
21000 Brookpark Road
Cleveland, OH 44135

[Corresponding U.S. Patent-Application Pending]

A difficulty with the proposed uses of ceramic materials for such high temperature applications as the stator vanes in aircraft and stationary gas turbines, and rotating parts in automotive gas turbines is their relatively low impact resistance. This invention is a method of improving the impact resistance of bodies of polycrystalline ceramic such as alumina, silicon nitride and silicon carbide, and bodies produced by the method. The body is provided with a layer of a low elastic modulus polycrystalline ceramic material which has microcracks therein, formed by such factors as thermalexpansion coefficient anisotropy, differences in thermalexpansion coefficients between phases of the material, and by changes in volume during phase transformations in the material. The layer can be applied by preforming the layer and then applying, or by hot pressing the material of the layer onto the body.

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Difficulties are often encountered in spacecraft assembly operations because of the existence of torsional stresses induced as a consequence of the tightening of certain bolts employed during such assembly operations. The present invention is a gear head wrench for applying torque to bolts without transferring torsional stresses to bolt-receiving structures. The wrench has an outer housing adapted to be coupled with a spacer interposed between the bolt head and the juxtaposed surface of the bolt-reciving structure for applying a balancing counter-torque to the spacer as torque is applied to the bolt head whereby the bolt-receiving structure is substantially isolated from torsional stress.

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Raw sewage treatment plants using conventional processes are finding it difficult to dispose of sludge solids. This invention utilizes a series of steps wherein the amount of final product is vastly reduced. The non-dissolved material is pyrolyzed to form an activated carbon and ash material. This carbon and ash is added to the sewer water and absorbs the organic matter and heavy metal ions dissolved in the water. Constant recycling of the carbon and ash reduce the amount of residual material to be disposed.

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It has become essential that the gasses in smokestack plumes and the like be monitored for the presence of pollutants such as NO, NO2, CO, CO2, SO2, and 03. In this invention, a laser source excites the atmospheric area of the pollutants until the beam causes the pollutants to fluoresce and emit a return signal to a detector. Analysis of this signal as compared to a known standard yields a signal indicative of the magnitude of the pollutant being analyzed.

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This invention is a generator for generating a hydrogen rich gas to be mixed with a dydrocarbon fuel for use in an internal combustion engine. Such a mixture considerably lowers the pollutants emitted by an internal combustion engine. The hydrogen rich gas is generated in a cylindrically shaped chamber by injecting air and hydrocarbon fuel at one end of said chamber, igniting the mixture of said air and hydrocarbon fuel to provide very hot combustion gases, by partial oxidation of the hydrocarbon. These gases move away from said ignition region to another region where water is injected to be turned into steam by the hot combustion gases. Either simultaneously with the injection of water or subsequently thereto, more hydrocarbon fuel is injected. The steam which is formed mixes with the hot gases present to yield a uniform hot gas whereby a steam reforming reaction with the hydrocarbon fuel takes place to produce a hydrogen rich gas.

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