Mcdermott Technology, Inc.

The Babcock & Wilcox Company

Richard W Goettler

Sung S Pak

Archie N Tolley

Charles A Hill

Eric A Barringer

Richard A Wagner

Ronald G Komoroski

Greg A Gunter

Ceramic composites containing weak interfacial boundaries included for the purposes of providing avenues for crack deflection with a resulting toughening of a ceramic body. Weak interfacial boundaries are created between constituents of the composite, such as matrix phases and any continuous and/or particulate reinforcements, and tungstate, molybdate, tantalate, and niobate compounds of the general formula ABO,. For tungstate and molybdate compounds of the general formula ABO,, B represents tungsten or molybdenum, and A represents a divalent cation. For tantalate and niobate compounds of the general formula ABO,, B represents tantalum or niobium, and A represents a trivalent lanthanide series cation. The ABO,tungstate, molybdate, tantalate, and niobate compounds may exist as barrier phases between the matrix and the reinforcements of the composite, or the ceramic body may contain discrete particulates, laminae, fibers, or whiskers of the ABO,tungstate, molybdate, tantalate, and niobate compounds. In a preferred embodiment, the reinforcing phases of the composite is a continuous single or polycrystalline fiber; however, particulate or whisker reinforcements will also benefit by being separated from the matrix phases by an interphase of an ABO,tungstate, molybdate, tantalate, or niobate. A non-brittle material may also be fabricated by creating multilayer laminar composites containing alternating lamina of the ABO,compound and a second phase.

Ceramic composites containing weak interfaces with ABO4 tungstate, molybdate, tantalate, and niobate phases

A ceramic fiber composite structure particularly suitable for use as a hot gas cleanup ceramic fiber composite filter and method of making same from ceramic composite material has a structure which provides for increased strength and toughness in high temperature environments. The ceramic fiber composite structure or filter is made by a process in which a continuous ceramic fiber is intimately surrounded by discontinuous chopped ceramic fibers during manufacture to produce a ceramic fiber composite preform which is then bonded using various ceramic binders. The ceramic fiber composite preform is then fired to create a bond phase at the fiber contact points. Parameters such as fiber tension, spacing, and the relative proportions of the continuous ceramic fiber and chopped ceramic fibers can be varied as the continuous ceramic fiber and chopped ceramic fiber are simultaneously formed on the porous vacuum mandrel to obtain a desired distribution of the continuous ceramic fiber and the chopped ceramic fiber in the ceramic fiber composite structure or filter.

Method of making a continuous ceramic fiber composite hot gas filter

A method for coating ceramic fibers such as Al.sub.2 O.sub.3 fibers includes immersing the Al.sub.2 O.sub.3 fibers in a polyelectrolyte solution. After the polyelectrolyte is allowed to adsorb on the fibers, the unabsorbed polyelectrolyte is washed from the fibers with a distilled water. The fibers are then deposited in an oxide solution such as SnO.sub.2. The SnO.sub.2 is allowed to adsorb on the fibers, and then the unabsorbed SnO.sub.2 is washed from the fibers with the distilled water. The fibers are then sintered at a temperature ranging from 400.degree. C. to 1200.degree. C.

Continuous deposition of bridge free interfacial coatings on

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Lynchburg, VA, United States of America

Richard W Goettler