Ceramic-metallic composites are disclosed along with the processes for their manufacture. The present invention improves high temperature strength of Al.sub.2O.sub.3—Al composites by displacing aluminum in the finished product with other substances that enhance the high temperature strength. Each process commences with a preform initially composed of at least 5% by weight silicon dioxide, and the finished product includes Al.sub.2O.sub.3, aluminum and another substance.

Ceramic-metallic composites are disclosed along with the processes for their manufacture. The present invention improves high temperature strength of Al.sub.2O.sub.3—Al composites by displacing aluminum in the finished product with other substances that enhance the high temperature strength. Each process commences with a preform initially composed of at least 5% by weight silicon dioxide, and the finished product includes Al.sub.2O.sub.3, aluminum and another substance.

A composite tooth is described for working the ground or rocks. The tooth includes a ferrous alloy having a portion reinforced at least partially by an insert. The portion reinforced by the insert is configured to allow, after in-situ reaction, the obtention of an alternating macro-microstructure of millimetric areas concentrated with micrometric globular particles of titanium carbides separated by millimetric areas substantially free of micrometric globular particles of titanium carbides. The millimetric areas concentrated with micrometric globular particles of titanium carbides form a microstructure in which the micrometric interstices between the globular particles are also filled by the ferrous alloy. The macro-microstructure generated by the insert is at least 2 mm, preferably at least 3 mm from a distal surface of the tooth.

A method is presented for producing hollow microspheres of metal oxides (HMOMS) and/or hollow metal silicates microspheres (HMSMS) in a transforming solution. The transforming solution contains an atom M, or an M-ion, or a radical containing M. M in the transforming solution has the thermodynamic ability to replace silicon atoms in hollow silica microspheres (HSMS) and/or hollow glass microspheres (HGMS). The maximum temperature for transformation is set by the chemical physical properties of the transforming solution, and the viscosity of the silica in the walls of the HSMS and/or the glass in the walls of the HGMS. Viscosity, of enough magnitude, helps retain the desired shape of the hollow sphere as it is transformed to HMOMS and/or HMSMS. Non-spherical shapes can be produced by increasing the transformation temperature whereby the viscosity of the walls of the HSMS and/or the HGMS is reduced. Transformation can take place at a single temperature or at several temperatures, each temperature for a separate hold time.

Methods are presented for: 1. production of micro composite castings and continuous production of sheets of micro composites, both consisting of hollow spheres in a matrix, 2. harvesting of HMOMS and HMSMS, and 3. specialty castings for anisotropic properties using 3-dimensional printing

Methods for producing oxide/metal composite components for use in high temperature systems, and components produced thereby. The methods use a fluid reactant and a porous preform that contains a solid oxide reactant. The fluid reactant contains yttrium as a displacing metal and the solid oxide reactant of the preform contains niobium oxide, of which niobium cations are displaceable species. The preform is infiltrated with the fluid reactant to react its yttrium with the niobium oxide of the solid oxide reactant and produce an yttria/niobium composite component, during which yttrium at least partially replaces the niobium cations of the solid oxide reactant to produce yttria and niobium metal, which together define a reaction product. The pore volume of the preform is at least partially filled by the reaction product, whose volume is greater than the volume lost by the solid oxide reactant as a result of reacting yttrium and niobium oxide.

The invention relates in a first aspect to a process for preparing a 3-dimensional body, in particular a vitreous or ceramic body, which comprises at least the following steps: a) providing an electrostatically stabilized suspension of particles; b) effecting a local destabilization of the suspension of particles by means of a localized electrical discharge between a charge injector and the suspension at a predetermined position and causing an aggregation and precipitation of the particles at said position; c) repeating step b) at different positions and causing the formation of larger aggregates until a final aggregate of particles representing a (porous) 3-dimensional body (green body) having predetermined dimensions has been formed; wherein the charge injector includes i) at least one discharge electrode which does not contact said suspension of particles or ii) a source of charged particles. A second aspect of the invention relates to a device, in particular for performing the above process, comprising at least the following components: a vessel for receiving an electrostatically stabilized suspension of particles, a charge injector, in particular including one or more electrodes or a source of high-energy charged particles, means for moving the electrode and/or the vessel in the x, y and z directions, a counter electrode arranged in the vessel for a contact with the suspension of particles, one or more sensors for determining geometrical and physical parameters within said vessel. In one preferred embodiment, said device further comprises a means for directing a beam of gas-ionizing radiation, in particular a laser beam, to a predetermined position within the vessel.

Methods for producing components for use in high temperature systems that include reacting a fluid reactant and a porous preform that has a pore volume and contains a solid oxide reactant that defines a solid volume of the porous preform. The method includes infiltrating the fluid reactant into the porous preform to react with the solid oxide reactant to produce a oxide/metal composite component, during which a displacing metal replaces a displaceable species of the solid oxide reactant to produce at least one solid oxide reaction product that has a reaction product volume that at least partially fills the pore volume. The oxide/metal composite component includes at least one oxide phase and at least one metal phase. The component is exposed to temperatures greater than 500 C. and the at least one oxide phase and the at least one metal phase exhibit thermal expansion values within 50% of one another.

Methods for producing components for use in high temperature systems that include reacting a fluid reactant and a porous preform that has a pore volume and contains a solid oxide reactant that defines a solid volume of the porous preform. The method includes infiltrating the fluid reactant into the porous preform to react with the solid oxide reactant to produce a oxide/metal composite component, during which a displacing metal replaces a displaceable species of the solid oxide reactant to produce at least one solid oxide reaction product that has a reaction product volume that at least partially fills the pore volume. The oxide/metal composite component includes at least one oxide phase and at least one metal phase. The component is exposed to temperatures greater than 500 C. and the at least one oxide phase and the at least one metal phase exhibit thermal expansion values within 50% of one another.

Ceramic and ceramic composite components suitable for high temperature applications and methods of manufacturing such components. The components are formed by a displacive compensation of porosity (DCP) process and are suitable for use at operating temperatures above 600 C., and preferably above 1400 C., and possess superior mechanical properties.

Ceramic and ceramic composite components suitable for high temperature applications and methods of manufacturing such components. The components are formed by a displacive compensation of porosity (DCP) process and are suitable for use at operating temperatures above 600 C., and preferably above 1400 C., and possess superior mechanical properties.