The Carborundum Company

Dart Industries Inc.

Roger S Storm

Jonathan J Kim

James Economy

Francis J Frechette

Luis C Wohrer

Steve G Cottis

Kai Y Chia

Viswanathan Venkatswaren

Wolfgang D Boecker

A method for forming a polycrystalline ceramic fiber which comprises blending about 5 to about 25 weight percent polymer, about 70 to about 95 weight percent silicon carbide powder and greater than 1 weight percent sintering aid; forming a fiber from the blend; and sintering the formed fiber. Preferably, the sintering aid is boron carbide. In addition, the fiber is preferably pre-sintered at a first temperature of from about 1700.degree. C. to 2300.degree. C. and then subsequently sintered at a second temperature of approximately 2000.degree. C. to about 2300.degree. C.

Process for making silicon carbide ceramic fibers

A sintered silicon carbide ceramic body preferably produced from a uniform mixture comprising from about 82 percent to about 99.4 percent by weight silicon carbide, from about 0.5 percent to about 10 percent by weight of a nitrogen containing aluminum compound and from about 0.1 to about 8 percent of a rare earth oxide, both reacted with oxygen, wherein said sintered ceramic body has a density greater than 90% percent of theoretical and a fracture toughness, as measured by a single edge notched beam test, of more than 7 MPam.sup.1/2 and method of making the same.

Silicon carbide bodies having high toughness and fracture resistance and

A p-oxybenzoyl copolyester which is flexible and soluble in organic solvents has recurring moieties of the formulas ##STR1## wherein the carbonyl groups of (B) are meta or para to each other and the oxygen atoms of (C) are meta or para to the sulfur atom thereof. Also described are organic solvent solutions of the p-oxybenzoyl copolyesters, molded articles made thereof and flexible coatings of such copolyesters on substrates.

P-Oxybenzoyl copolyesters comprising thiodiphenol components and having

Ceramic compositions that may be injection molded and subsequently sintered are described. The compositions include minor amounts of organo-titanates which materially reduce the viscosity of the compositions. The reduction in viscosity is particularly effective in compositions containing high loadings of silicon carbide as the ceramic material. The organo-titanates found useful are represented by the formula:

Ceramic composition suited to be injection molded and sintered

A one-step curing method for the manufacture of neutron absorbing articles, such as those of long thin plate form for use in storage racks for spent nuclear fuel, includes curing a mixture of boron carbide particles, phenolic resin in liquid state and phenolic resin in particulate solid form at an elevated temperature to produce a neutron absorbing article containing at least 6% of B.sup.10 content from the boron carbide thereof, 60% to 80% of boron carbide particles and 40% to 60% of irreversibly cured phenolic polymer, with the proportion of weight of phenolic resin in liquid state to that of phenolic resin in solid state being within the range of about 1:0.5 to 1:4, the temperature of the cure being in the range of about 130 to 200.degree. C. and the cure being effected over a period of about two to twenty hours. Because of the use of solid resin, in particulate form, together with the resin in liquid state, the neutron absorbing articles made include better bonds between the polymer and the boron carbide particles than would be obtainable by using the normally solid resin only and the phenolic polymer content of the article is greater than that which would be obtainable by a one-step cure effected when the curable phenolic resin is all in the liquid state and the mixture is not held in article form under compacting or pressing pressure.

One-step curing method for manufacture of neutron absorbing plates

Polyesters of para-oxybenzoyl are infusible and very resistant to acids and solvents, thus limiting the means by which such polymers can be fabricated. Such a polyester is made more amorphous, thus improving compression moldability, by subjecting it to a high temperature treatment, followed by a rapid quench. The resulting polymer has reduced crystalline orientation, as evidenced by X-ray diffraction patterns, and molded articles thereof have improved flexural strength, without adversely affecting the modulus. The thermal treatment is carried out on the polymer by heating at a temperature of at least 300.degree.C, and up to just below the decomposition temperature of the polymer, followed by quenching of the hot polymer.

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Williamsville, NY, United States of America

Roger S Storm