W. R. Grace Co.-conn.

W. R. Grace Co.

Frederick J Parker

Awdhoot V Kerkar

Rasto Brezny

A bioremediation support for the support of microorganisms used in the biotreatment of an aqueous waste stream or contaminated vapor is made of a low-density siliceous glassy material. This material has a cellular or frothy texture, large pores of greater than 1,000 Anstrom units in diameter dispersed throughout the material, a high macropore volume in pores of greater than 1,000 .ANG. of more than 0.3 cc/cc and a BET surface area of greater than 10 m.sup.2 /g. A preferred material is pumice.

Low density glassy materials for bioremediation supports

Ternary CaO-TiO.sub.2 -SiO.sub.2 compositions are discussed. These compositions are useful as sintering aids for silicon nitride sintering. Use of these ternary compositions allows silicon nitride to be effectively sintered at lower temperatures than when conventional yttria sintering aids are used.

Fabrication of dense SI.sub.3 N.sub.4 ceramics using CaO-TiO.sub.2 SiO.sub.

A low thermal expansion ceramic composition having a predominant Al.sub.2 TiO.sub.5 phase along with zirconium titanate and zirconia phases. The final overall ceramic composition after firing has a low thermal expansion between 24.degree.-1000.degree. C. of not greater than 1.5.times.10.sup.-6 .degree. C..sup.-1 and a thermal stability in air such that (a) upon heating to 1200.degree. C. for at least 4 hours there is substantially no decomposition of the Al.sub.2 TiO.sub.5 phase to rutile or alumina as measured by X-ray diffraction, (b) physical growth after thermal cycling between 200.degree. and 1150.degree. C. for 300 cycles does not exceed 1.5%, and (c) the composition maintains a low average thermal expansion between 24.degree.-1000.degree. C. of not greater than 1.5.times.10.sup.-6 .degree. C..sup.-1 after the isothermal heating or cycling conditions. The composition is preferably made by forming a mixture of the equivalent of 50-90 volume percent Al.sub.2 TiO.sub.5 or a solid solution having a substantial amount of Al.sub.2 TiO.sub.5 in the solid solution, and zirconium titanate and then heating the mixture at a temperature of 1250.degree. C. or higher.

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Columbia, MD, United States of America

Frederick J Parker