Gas Research Institute

The Carborundum Company

Other

The Standard Oil Company

Kennecott Corporation

Stemcor Corporation

Martin R Kasprzyk

Francis J Frechette

James A Hirsch

Elwood B Hausler

Charles J Boos

Elmer G Smith

Carl H McMurtry

Wolfgang D Boecker

Richard E Tressler

Michael P Dunn

Monika O TenEyck

Monika O Ten Eyck

Joseph S Zanghi

Douglas J McDowell

An integral ceramic insert for a radiant tube. The insert has a helical shape and contains ceramic material; and it has a thermal expansion rate of less than 6.0&times;10 meters/meter/degree Celsius and a thermal conductivity of at least 0.2 calories/centimeter/second/degree Celsius. The diameter of the insert is from about 2 to about 10 inches, and it has a length such that the ratio of its length to its diameter is from about 2/1 to about 8/1. The helical shape of the insert contains one or more pitches of from about 2 to about 32 inches, each which defines a helix angle of from about 15 to about 80 degrees.

Insert for a radiant tube

A method of making a ceramic tube of silicon and silicon carbide comprising the steps of covering a mandrel with carbon fiber material; infiltrating the carbon fiber material with a thermoset resin; curing the resin to render the carbon fiber material rigid and produce a green body; removing the mandrel to produce a free-standing body; treating the free standing body with graphite to fill voids and render the green body gas tight and infiltrating the green body with molten silicon to form a silicon and silicon carbide ceramic tube.

Method of preparing tubular ceramic articles

An improved radiant heat transfer tube with internal fins is provided. Optimum design characteristics for the number of fins, the height or length of the fins and the twist of the fins is provided to enhance convective and radiant heat transfer from combustion gases inside the tube to the inside surface of the tube. The fin design applies to tubes fabricated from high temperature metal alloys, monolithic ceramics, metal matrix composites or ceramic matrix composites.

Radiant tubes having internal fins

A high temperature, preferably polycrystalline, ceramic fiber having a selectable diameter of between 1 and 200 microns. The fiber is stable in an inert atmosphere at a temperature above about 1700.degree. C. and is often stable even in air at a temperature above 1500.degree. C. The fiber comprises a sintered ceramic powder having a maximum particle size less than the diameter of the fiber and an average particle size less than 0.2 times the diameter of the fiber. The ceramic powder is also stable in an inert atmosphere at a temperature above about 1700.degree. C. At least 90% of the ceramic is selected from borides, nitrides, carbides, and silicides. The fiber is characterized by a smooth surface and is preferably out of round. The invention further comprises a textilable sinterable filament, comprising a flexible polymer matrix containing high temperature sinterable ceramic powder particles. The ceramic powder particles are selected from ceramic borides, nitrides, carbides, and silicides. The diameter of the filament is from 2 to 300 microns. The invention also comprises the method for making textilable filament by fiberizing a mixture of a polymer and a sinterable non-oxide fiber and the method wherein the high temperature ceramic fiber is prepared by sintering the textilable sinterable filament as previously described. The invention also includes composites containing such filaments.

Non-oxide sintered ceramic fibers

The present invention relates to apparatus for producing tubular ceramic articles. The apparatus is comprised of a vertically positioned electrical induction furnace; a plurality of spaced concentrically arranged tubular forms, which fit and are arranged vertically within the furnace; one or more supply hoppers for holding particulate feed materials, and; supply lines to dry cast feed materials into the spaces between and around the forms. The forms may then be removed leaving separate vertical, hollow columns of particulate feed materials concentrically arranged within the furnace. The furnace is then heated causing the particulate materials to react forming a tubular ceramic article within the furnace.

Apparatus for the production of ceramic articles

The present invention relates to composite articles of manufacture comprised of a continuous phase of silicon containing a discontinuous matrix of particulate material selected from silicon carbide, carbon, or mixtures thereof. The particulate materials have a minimum size of about fifty microns, and more preferably for enhanced performance, a minimum size of 100 microns. The present articles contain from about thirty to about seventy, and more preferably from about 35 to about 65 percent by volume of silicon. The present composites have strains to failure at high temperatures substantially higher than the reaction bonded silicon carbide composites of the prior art. The present composites also have a resistance to thermal stress at elevated temperatures superior to the prior art composites. In such respects, the present composite materials have characteristics more resembling a metal than a ceramic. The present composites are especially useful in the fabrication of shaped articles, for example, tubular articles.

Ceramic articles, methods and apparatus for their manufacture

Dense, strong, composite materials are produced from mixtures of silicon and silicon carbide. The composite materials are characterized by a mixture of finely-divided silicon carbide in a substantially continuous matrix of silicon. The composite materials contain from about 40 to about 60 percent by volume silicon carbide and from about 60 to about 40 percent by volume silicon. The composite materials are produced by initially producing a finely-divided silicon carbide starting component and forming the component into a green body of the desired shape. The green body is subsequently impregnated with molten silicon in the absence of any substantial amount of carbon. Suitably, a thermoplastic resin binder may be added to the silicon carbide starting material to aid in forming the green body. The impregnation step may be carried out by surrounding the green body with finely-divided silicon metal and heating the covered body to a temperature above the melting point of silicon. The composite materials described have flexural strength of over about 90,000 psi at 1100.degree. C., elastic modulus of about 38 million psi at room temperature, are essentially non-porus and have densities ranging from about 2.6 to about 2.8 g/cc.

Composite material of discontinuous silicon carbide particles and

The present invention relates to methods and apparatus for producing tubular articles of silicon carbide and silicon. The articles contain silicon in both metallic and in chemically combined form. The method consists of the steps of concentrically positioning a vertical tubular columns of particulate silicon contiguous to a hollow, vertical tubular columns of particulate silicon carbide, carbon, or mixtures of silicon and carbon, and heating the adjacent columns to a siliciding temperature. The silicon component infiltrates the column containing the particulate silicon carbide, carbon, or mixtures thereof, forming a tubular product. The apparatus consists of supply hoppers for holding the particulate feed material, a loading means comprised of spaced, concentrically arranged, tubular forms. The loading means is positioned within a vertically positioned electrical induction furnace. Particulate feed materials are dry cast in the spaces between and around the forms. The loading means is then removed leaving separate vertical, hollow columns of particulate feed materials concentrically arranged with the furnace. The furnace is then heated from top to bottom to a siliciding temperature. The silicon component infiltrates the column containing silicon carbide, carbon or mixtures thereof to form a dense, tubular silicon-silicon carbide product.

Method of producing tubular ceramic articles

Non-oxide refractory foams, possessing controlled permeability and uniformity, are prepared by impregnating an organic polymer foam material with a fluid, particulate slurry of a first refractory material, drying, applying to the dried, impregnated material a second refractory material which has a lower melting point than the first refractory material and thereafter heating, at a temperature sufficient to cause melt infiltration of the second refractory material into the impregnated material, thus producing inert and dimensionally stable composite refractory foams having broad utility as particulate filters or carriers.

Composite refractory foams

New porous semiconductor dopant carriers are disclosed together with a method for the diffusion doping of semiconductors by the vapor phase transport of an n or p type dopant, such as phosphorus, arsenic, antimony, boron gallium, aluminum, zinc, silicon, tellurium, tin and cadmium to the semiconductor host substrate; wherein the dopant carrier is comprised of a rigid, multiphase dimensionally stable refractory foam, formed through the impregnation, and subsequent thermal destruction of an open-celled organic polymer foam.

Foam semiconductor dopant carriers

A composition comprising negatively doped hot pressed particulate silicon carbide, the process for making the composition, an electrical hot surface fuel ignitor manufactured from the composition, a silicon brazed electrical connection for the ignitor and an ignitor circuit containing a dropping resistance.

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Ransomville, NY, United States of America

Martin R Kasprzyk