Abstract: The invention provides an alternative to conventional sol-gel methods that utilize undesirably high amounts of a stabilizing agent such as TMAH and a gelling agent such as methyl formate. The method involves the steps of (a) providing a colloidal silica dispersion containing a stabilizing/gelling agent, where only a portion of the molecules of the agent ionize, and (b) subsequently adding to the silica dispersion a pH-reducing additive. The stabilizing/gelling agent has a dual function. The agent, e.g., an amine, initially acts as a stabilizer in the silica dispersion in that a portion of its molecules ionize, while an appreciable amount of the agent remains non-ionized. The agent later transforms in situ to a gelling agent upon addition of a pH-reducing additive. Specifically, as the pH-reducing additive lowers the pH to values at or around the pK.sub.

Abstract: This invention relates to novel ecologically compatible water-based stable mullite precursor sols, mullite composites, and methods for making the same. The mullite precursor sols are synthesized using tetraethoxysilane and aluminum nitrate in water. The tetraethoxysilane is hydrolyzed with water and ammonium hydroxide catalyst to make a silica sol, which is then quenched with an aqueous solution of aluminum nitrate. The mullite precursor sols of the invention may be used to make highly densified ceramic composites.

Abstract: Applicants have developed a unique process for preparing a shaped article comprising an ion exchange composition and a hydroxy oxide binder. The ion exchange compositions include metallotitanates, metallogermanates, pillared clays and metal phosphonates. The process involves combining the ion exchange composition with a binder precursor and water, forming the mixture into a shaped article and heating the article at a temperature of about 85.degree. C. to about 120.degree. C. These shaped articles are useful for removing metal ions such as cesium from feed streams.

Abstract: Method of making porous, fibrillose bodies from fibrils bonded together into a self-supporting structure. A mixture of fibrils and a viscous, non-newtonian, liquid vehicle including an organic hydrosorbent and water is (1) injected into a mold, (2) frozen in the mold to form a frozen precursor of the article, (3) ejected from the mold while still frozen, (4) freeze-dried, and (5) finally heated to remove the hydrosorbent and bond the particles together. The process is particularly effective for making fibrillose preforms for infiltrating with metal in the manufacture of metal matrix composites.

Abstract: A method of making a mechanically stable, fiber having an inclusion of ion-conducting material which includes the steps of coating a single-crystal or polycrystalline .alpha.-alumina fiber with a zirconia or a hexaluminate precursor, optionally heating the coated fiber to dry the coating, when the coating is applied as a suspension or sol, heating the coated fiber to a temperature of about 1000.degree. to 1800.degree. C. to promote the growth of alpha-alumina toothlike extensions in the coating and epitaxial formation of the zirconia or hexaluminate on the sides of the extensions, embedding the fiber in an .alpha.-alumina matrix material, and heating the resulting fiber-matrix composite to react and texture the coating and densify the assembly.

Abstract: A method of making a lightweight, microwave electronic structure includes the steps of forming a rigid, glass structure having a desired density by a sol-gel process and thereafter uniformly coating the formed glass structure with an adherent and uniform conductor. The sol-gel process may be carried out by polymerizing a mixture comprising silicon alkoxide, water and an alcohol. The coating process may be carried out by coating the glass structure with a solution comprising an organic compound of a metal dissolved in an organic solvent and thereafter volatizing the organic solvent.

Abstract: An oxide ceramic composite suitable for fabricating components of combustion turbines and similar high temperature environments. The composite is fabricated by dispersing metal particles in a fiber preform and infiltrating the fiber preform with sol-gel matrix precursor material. Alternatively, the metal particles are mixed into the sol-gel matrix precursor material and the preform is infiltrated with the mixture. Later in the fabrication process, the metal particles oxidize and become oxidized metal when the sol-gel matrix precursor material is sintered. The oxidized metal has more volume and mass than the metal particles. As a result, the oxidized metal contributes to increasing the density of the composite so that it is suitable for use in combustion turbines and similar high temperature environments.

Abstract: A ceramic component is manufactured rapidly using a mold made directly from a solid freeform manufacturing process. Solid freeform fabrication, or rapid prototyping, procedures are used to generate molds of materials that are soluble or otherwise fugitive. A gel casting suspension containing ceramic and emulsifying agents is poured into the cavity of the mold and caused to set. The mold is then removed by dissolution or heat treatment, leaving intact the gelcast part. Conventional procedures are then utilized to densify the gelcast component to the required final component. Time consuming and expensive machine tooling procedures are virtually eliminated. Ceramic components are generated rapidly in a cost effective manner.

Abstract: The present invention is a method of preparing a ceramic article which includes compacting a particulate alloy of a primary oxide and a secondary oxide to form a blank. The primary oxide is zirconium oxide and the secondary oxide is selected from MgO, CaO, Y.sub.2 O.sub.3, Sc.sub.2 O.sub.3,CeO.sub.2 and rare earth oxides and combinations thereof. The blank is sintered in contact with a smectite containing sol.

Abstract: The present invention provides a method of producing composite oxide ceramics which is capable of efficiently producing single-phase multi-component metal oxide ceramics having less impurity phase and excellent dielectric characteristics, by a simple process comprising sintering at a low temperature. The method has the steps of mixing a metallic hydroxide or hydrous gel with a plurality of metallic oxide powders to prepare a raw material mixture powder, activating the raw material mixture powder by mechanochemical treatment for grinding the raw material mixture powder with a degree of impact, which provides a centrifugal effect of 15 or more, to form a precursor, and synthesizing composite oxide ceramics by heat treatment of the activated raw material mixture powder (precursor).

Abstract: The well known slip casting process for the production of ceramic green parts, in which hardening is achieved by water removal with porous molds, is characterized by disadvantages in terms of strength, shrinkage during drying and problems with cracking during drying. The present invention avoids these disadvantages and produces ceramic green parts by changing the surface potential of powder particles in the slip instead of by removing water. Further more the coagulation strength is increased by adding polymers or extremely fine divided colloidal particles.

Abstract: A process for forming a ceramic alumina-based abrasive grain from a sol gel which contains aluminum oxide monohydrate, a dissolved metal containing sintering aid and sufficient sodium and/or calcium compound to provide in the ceramic from above about 0.05 to about 1.8 weight percent sodium plus calcium, provided that the weight percent calcium is from 0 to about 1.8 and the weight percent sodium is from 0 to about 0.4. The high sodium and calcium is permitted due to rapid heating of the sol gel after drying through a temperature range of from below about 800.degree. C. to above about 1200.degree. C., prior to sintering the dried gel at a temperature above 1200.degree. C. A grain made by the process and coated, bonded and non-woven abrasive articles comprising the grain.

Abstract: Parts from ceramic and/or metal powder(s) are shaped by a process that comprises the steps of (1) forming a mixture comprising ceramic and/or metal powder(s), a gel-forming material chosen from the class of polysaccharides known as "agaroids", a gel-forming solvent, and a gel strength enhancing agent, and said mixture being formed in a blender that provides a shearing action and being heated to raise the temperature of the mixture to about 70.degree. C. to 100.degree. C.; and (2) molding the mixture at a temperature sufficient to produce a self-supporting structure comprising the powder and gel. The parts exhibit excellent green strength and are rapidly fired without cracking, distortion or shrinkage problems.

Abstract: An improvement in a thermally insulating component for an engine part, made by sintering from ceramic materials, comprises, the thermally insulating component having a composition, consisting of a mixture of zirconium oxide in the range of about 5% to about 25% by volume and mullite in the range of about 75% to about 95% by volume. Further, the mixture of zirconium oxide and mullite is obtained by chemically mixing the zirconium oxide and mullite in their molecular states, rather than mechanically mixing them. Another feature of this invention includes, forming said thermally insulating component by slip casting and pressureless sintering the mixture of zirconium oxide and mullite at a temperature no greater than 1700.degree. C. This improvement in a thermally insulating component for an engine part, made from a mullite-zirconia ceramic composite, embodying the present invention, is particularly useful in making flame decks for cylinder heads, and insulating coverings for pistons and exhaust ports.