Saint-gobain/norton Industrial Ceramics Corporation

Saint-gobain Industrial Ceramics, Inc.

Norton Company

Saint-gobain Ceramics & Plastics, Inc.

Ajay K Garg

Arup K Khaund

Brahmanandam V Tanikella

Mark R Young

Lawrence E Orne

Ralph Bauer

Vimal K Pujari

Michael D Kavanaugh

Craig A Willkens

Ronald W Trischuk

Edward Lilley

William R Delaney

Porous ceramic particles can be fragmented by generating a gas inside the pores at a sufficient pressure to cause the particles to be fragmented. The preferred way of generating the pressure is by immersing the particles in a liquid that at ambient temperatures and pressures is a gas until the liquid is absorbed into the pores and thereafter rapidly changing the conditions such that the liquid becomes a gas resulting in explosive fragmentation of the ceramic particles.

Explosive fragmentation process

Alpha alumina abrasive grits which are particularly well-suited to medium to low pressure grinding applications wherein the grits comprise uniformly dispersed microvoids.

Abrasive grain

CMP formulations comprising alumina particles and an iodate oxidizer can be stabilized against pH drift during use by acidification using an organic acid. Formulation pH stability can be further enhanced by treating the formulation at an elevated temperature before it is used.

CMP formulations

CMP processes and products employ aluminas comprising alpha alumina particles having a particle width of less than 50 nanometers and a surface area of at least 50 m,/gm.

CMP products

A polishing slurry, useful in optical or CMP applications, comprises a ceria with a BET surface area of at least 10 m,/gm. The slurry may be made by subjecting a commercial ceria slurry comprising agglomerates to a mechano-chemical treatment at a pH of from 9 to 11 using media that are low purity alpha alumina or zirconia. Preferred slurries maintain a positive surface charge at all pH values. CMP slurries preferably comprise in addition an anionic surfactant to aid in removal of surface residues.

Ceria powder

Firing sol-gel alumina particles

Nano-sized powders of alpha alumina can be obtained from a boehmite gel doped with a barrier-forming material such as silica that is then dried, fired and comminuted to powder form.

Nano-sized alpha alumina particles having a silica coating thereon

Sol-gel alumina that is dried but unfired can be explosively comminuted by feeding the dried gel into a furnace held at temperatures above those at which vaporizable materials are eliminated from the particles of gel. At suitably elevated temperatures the firing is sufficient to form fully densified alpha alumina particles of a size suitable for direct use as abrasive grits.

Dry milling an alpha alumina precursor produces direct conversion to alpha alumina at room temperature.

Production of alpha alumina

The use of purified process materials in the production of a seeded sol-gel alumina abrasive results in an abrasive of superior properties.

Sol-gel alumina abrasives

The invention provides a process for recovering abrasive grains from vitreous bonded materials by boiling the material in an aqueous solution of an alkali metal base.

Reclamation of abrasive grain

Alpha alumina abrasive grits with grain boundaries modified with at least one of yttria and a rare earth metal oxide, and one or more oxides selected from the oxides of magnesium and/or transition elements, perform at enhanced levels if at least the yttria and/or rare earth metal oxide modifiers are present within the body of the grit in concentrations at least as high as their concentrations at the surface of the grit.

Modified sol-gel alumina

Seeded sol-gel alumina abrasive grits with improved grinding performance incorporating alkali metal oxides selected from rubidium and cesium oxides.

Modified alpha alumina particles

Aqueous suspensions of ceramic particles in which the particle are coated by a metal oxide sintering aid or metal hydroxide precursor thereto and which have a sufficiently high solids content to produce casting slips which can yield net shape castings are provided. The suspensions are produced by concentrating lower solids content suspensions by crossflow filtration which disrupts hydroxide gels which inherently form by interaction of the coating with water. The resultant highly loaded aqueous suspensions may be used in net shape casting to produce cast bodies of high dimensional stability, high green strength, and with a low incidence of cracking.

Growing community of inventors

Northborough, MA, United States of America

Ajay K Garg