Gte Sylvania Incorporated

Gte Products Corporation

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Joseph J Cleveland

Chester J Dziedzic

Robert W Wolfe

Ray L Newman

Richard N Kleiner

William L Mingos

James Q Steigelman

Frank Rymas

Raymond E Dorazio

Leadom A Warner

A corrosion resistant ceramic article consisting essentially of a first phase of silicon nitride and a second continuous phase of cordierite. The article is formed so that the surface is a substantially continuous oxide material for enhancing the corrosion resistance.

Cordierite-silicon nitride body

A heat recuperator comprises a cross-flow ceramic core within a housing. The housing includes an inlet conduit and an outlet conduit for a gas to be heated. The housing also includes means for thrice passing said gas through the ceramic core in order to improve the diffusion of the gas through the core.

Triple pass ceramic heat recuperator

In the manufacture of sintered silicon nitride articles by hot isostatic pressing, multiple silicon nitride parts are encapsulated within a single capsule for the pressing operation. Suitable spacers placed between the parts ease separation thereof after sintering.

Method for making sintered silicon nitride articles

In the manufacture of sintered silicon nitride articles by hot isostatic pressing, silicon nitride preforms are assembled in a stack with spacers between the preforms. The stack is completely enveloped in refractory metal foil and then encapsulated within a single capsule for the pressing operation.

Method of preparing silicon nitride articles for sintering

In the manufacture of sintered silicon nitride articles by hot isostatic pressing, silicon nitride preforms are assembled in a stack with spacers between the preforms. A plurality of such stacks are inserted in a glass tube closed at one end. The glass is melted around each stack to encapsulate each stack in a single sealed capsule.

Process for sintering silicon nitride articles

A heat recuperative assembly includes a cross-flow ceramic core structure of stacked ribbed layers, the ribs forming channels for the passage of heat transfer fluids, the layers sealed by ceramic cement filled in the outermost channels of each layer. In addition, the ribs adjacent the outermost ribs are more closely spaced in order to provide greater contact area for sealing.

Ceramic heat recuperative structure and assembly

Cross-flow ceramic recuperators are useful in industrial waste heat recovery in an assembly in which the ceramic recuperator is held by a metallic housing adapted for retrofitting to the metallic fittings of existing furnaces, ovens and preheaters. The assembly is characterized by at least two insulating layers inside the conduit portions leading from the operating hot faces of the ceramic core, whereby the operating efficiency of the assembly is increased.

Insulated housing for ceramic heat recuperators and assembly

Cross-flow ceramic recuperators are useful in industrial waste heat recovery in an assembly in which the ceramic recuperator is held by a metallic housing adapted for retrofitting to the metallic fittings of existing furnaces, ovens and preheaters. The housing is characterized by two pairs of opposing apertured plates held against the inlet and outlet faces of the ceramic recuperator by spring biased through-bolts.

Housing for ceramic heat recuperators and assembly

Synthetic cordierite (2MgO.2Al.sub.2 O.sub.3.5SiO.sub.2) ceramic bodies exhibiting high strength and low thermal expansion are produced by (1) pelletizing talc, clay and alumina in a ratio to yield a nearly stoichiometric composition, (2) sintering the pellets to form cordierite, (3) milling the pellets in non-contaminating media to about 1 to 10 microns particle size, (4) consolidating the particles, and (5) sintering to a polycrystalline body. Such bodies possess good to excellent thermal shock resistance, and are useful, for example, as components in gas turbine engines.

Method for producing high strength low expansion cordierite bodies

In the formation of cylindrically shaped heat regenerators from ceramic honeycomb structures for use in gas turbine engines, a gas-impervious seal of the peripheral honeycomb cells and a high strength outer ring are formed simultaneously in an apparatus which provides for surrounding the outer wall of the honeycomb structure with a castable ceramic composition suitable for forming the outer ring, contacting a peripheral area of the upper surface of the honeycomb structure defining a predetermined number of peripheral cell openings with a (different) ceramic slurry composition, evacuating the honeycomb cells whose openings are contacted with the slurry composition through corresponding openings in the lower surface of the honeycomb structure in order to promote flow of the slurry into the evacuated cells, thereby forming a gas impervious seal of these peripheral cells, while simultaneously vibrating the honeycomb structure and castable composition in order to promote flow and intimate contact of the castable composition with the outer wall of the structure, thereby to form an outer adherent layer of the castable composition on the wall of the structure. After drying, the honeycomb structure with the filled peripheral cells and the outer adherent layer of ceramic may be fired in the conventional manner to convert the structure to a unified ceramic regenerator having a sealed outer ring.

Method for forming a sealed outer ring for ceramic regenerator

Layered composite cross-flow ceramic recuperators having minimal leakage between layers and consequent high efficiencies are utilized for industrial waste heat recovery in an apparatus in which the ceramic recuperator is surrounded by a metallic housing adapted for coupling to the metallic fittings of existing furnaces, calciners, ovens and preheaters. The ceramic recuperators are formed from stacks of bi-sectioned ribbed layers, the sections of each layer being sealed together to minimize leakage of the heat transfer fluids between layers, and thus to increase the efficiency of the heat transfer.

Composite ceramic cellular structure and heat recuperative apparatus

High cell density (125 Cells/inch) cross-flow ceramic recuperators having high efficiencies are utilized for industrial waste heat recovery in an apparatus in which a ceramic recuperator core is surrounded by a metallic housing adapted for coupling to the metallic fittings of existing furnaces, ovens and preheaters. Insulating and sealing layers between the core and housing minimize heat loss through the housing and prevent leakage of the heat transfer fluids past the core.

Heat recuperative apparatus incorporating a cellular ceramic core

There is disclosed a method for producing a bilayered green ceramic tape having a corrugated first layer and a substantially flat second layer bonded thereto. The method comprises the steps of supplying a flat pliable first layer of green ceramic material, forming said flat first layer to a shape having a corrugated cross section, and bonding a flat second layer to one side of the corrugated layer.

Method for producing a bilayered green ceramic tape

A ceramic cellular structure having a cell density of up to 1600 cells per square inch and wall thicknesses down to 2 mils is produced by a process which comprises: (1) forming a slurry consisting essentially of finely divided sinterable solid particles of ceramic raw materials and a controlled amount of a plastic supporting matrix containing thermoplastic resin, a thermosetting resin, a plasticizer, an organic solvent and a small amount of a deflocculant; (2) ball milling the slurry; (3) casting the slurry in the form of a film; (4) removing the solvent to produce a self-supporting green ceramic tape; (6) molding a portion of the tape to form a corrugated first member; (7) providing another portion of the tape to form a substantially flat second member; (8) forming a first bilayer by bonding the second member to the nodes of the first member; (9) mutually bonding a predetermined number of bilayers substantially identical to the first bilayer to form a cellular green structure of a desired shape; and (10) firing the green structure at a temperature sufficient to form a sinter-welded polycrystalline ceramic structure. The fired structures, after being subjected to various finishing operations, are useful as rotary heat regenerators, stationary heat recuperators and catalyst supports.

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Wysox, PA, United States of America

Joseph J Cleveland