Abstract:
A method of fabricating a ceramic article includes serially depositing first, second and third different materials within a porous structure using, respectively, first, second and third different processing techniques, to form a ceramic-containing article. The first, second and third materials differ by at least one of composition and microstructure. The first, second and third different processing techniques differ by at least one of modes of delivery of precursor materials into the porous structure and formation mechanisms of the first, second and third different materials from the precursor materials. The deposition of the first material is controlled such that there are first residual voids in the porous structure in which the second material is deposited. The deposition of a second material is controlled such that there are second residual voids in the porous structure in which the third material is deposited.
Abstract:
An article includes a substrate and a coating on the substrate. The coating includes a compound of aluminum, boron and nitrogen in a continuous chemically bonded network having Al-N bonds and B-N bonds. Also disclosed is an article wherein the substrate is a plurality of fibers and the coating is a conformed coating of a compound of aluminum, boron and nitrogen having Al-N bonds and B-N bonds. The fibers are disposed in a matrix. Also disclosed is a method of protecting an article from environmental conditions. The method includes protecting a substrate that is susceptible to environmental chemical degradation using a coating that includes a compound of aluminum, boron and nitrogen having Al-N bonds and B-N bonds.
Abstract:
A heat transfer system is disclosed in which, an electrocaloric material includes a copolymer of a monomer mixture including (i) vinylidene fluoride, (ii) an addition polymerization monomer selected from tetrafluoroethylene, trifluoroethylene, or a monomer smaller than trifluoroethylene, and (iii) a halogenated addition polymerization monomer different than (ii) that is larger than vinylidene fluoride. The electrocaloric material also includes an additive selected from a nucleating agent having a polar surface charge, electrocalorically active solid particles, or a combination thereof. Electrodes are disposed on opposite surfaces of the electrocaloric material, and an electric power source is configured to provide voltage to the electrodes. The system also includes a first thermal flow path between the electrocaloric material and a heat sink, and a second thermal flow path between the electrocaloric material and a heat source.
Abstract:
A method of fabricating a ceramic article includes providing a porous body that includes a plurality of fiber bundles that has an intra-bundle porosity and an inter-bundle porosity, infiltrating the intra-bundle porosity and the inter-bundle porosity with a mixture of particles in a liquid carrier, the particles having an average size selected with respect to at least the intra-bundle porosity, removing the liquid carrier from the porous body to deposit the particles in the intra-bundle porosity and in the inter-bundle porosity, infiltrating a preceramic polymer into a remaining intra-bundle porosity and a remaining inter-bundle porosity, and thermally converting the preceramic polymer to a ceramic material.
Abstract:
Disclosed is a method for providing a crystalline ceramic material. In an example, the method includes providing a silicon-containing preceramic polymer material that can be thermally converted to one or more crystalline polymorphs. The silicon-containing preceramic polymer material includes dispersed therein an effective amount of dopant particles. The silicon-containing preceramic polymer material is then thermally converted to the silicon-containing ceramic material. The effective amount of dopant particles enhance the formation of at least one of the one or more crystalline polymorphs, relative to the silicon-containing preceramic polymer without the dopant particles, with respect to at least one of formation of a selected polymorph of the one or more crystalline polymorphs formed, an amount formed of a selected polymorph of the one or more crystalline polymorphs formed, and a temperature of formation of the one or more crystalline polymorphs.
Abstract:
A method of preparing a composite preform includes applying a tacky preceramic-polymer-based adhesive on a first fiber array arranging a second fiber array on the first fiber array, the adhesive holding the first and second fiber arrays together. A composite component is also disclosed.
Abstract:
A composite component includes a fiber array, a plurality of platelets bridging between fiber filaments of the fiber array and rigidizing the fiber array, and a resin-based phase disposed within voids of the fiber array. A method of making a composite component is also disclosed.
Abstract:
An erosion resistant and hydrophobic article includes a core that has a first hardness and a surface on the core. The surface includes a plurality of geometric features that have a second, greater hardness. The geometric features define a surface porosity by area percent and a corresponding surface solidity by area percent. The surface includes a ratio of the surface solidity divided by the surface porosity that is 1.8 or greater. The geometric features and the ratio establish the surface to be hydrophobic, and the second, greater hardness and the ratio establish an erosion rate of the surface that is equal to or less than an erosion rate of the core under identical erosion conditions.
Abstract:
An embodiment of a method includes fabricating a first single crystal boule (24;124A) having a uniform composition and grain orientation. The first uniform single crystal boule (24;124A) is divided into a first plurality of layered shapes (20A;120A;220A;320A). The shapes of the first plurality (20A;120A;220A;320A) are stacked with at least a second plurality of layered shapes (20B;120B;220B;320B) along a first axis. The second plurality of layered shapes (20B;120B;220B;320B) have at least one physical aspect differing from at least one corresponding physical aspect of the first plurality of layered shapes (20A;120A;220A;320A). The first plurality of layered shapes (20A;120A;220A;320A) and at least the second plurality of layered shapes (20B;120B;220B;320B) are joined via a field assisted sintering technique (FAST) to form a bulk component.