Advanced Composite Materials Corporation

Atlantic Richfield Company

Ronald L Beatty

James F Rhodes

Chester J Dziedzic

Floyd H Wyman

Cutting tools are disclosed which are comprised of composite bodies comprising a ceramic matrix reinforced by ceramic whiskers. The ceramic matrix may be alumina or silicon nitride, and may contain toughening components. The whiskers are preferably silicon carbide, but may be other known ceramic whiskers. Whisker content in the composite is 2-40%, with higher contents generally used for tools when the expected service involves interrupted cutting and lower contents generally used for continuous cutting tools.

Reinforced ceramic cutting tools

Method of cutting using silicon carbide whisker reinforced ceramic

The invention features methods and apparatus for obtaining silicon carbide whiskers on a continuous basis. Rice hulls or other carbon and silicon containing feed materials are continuously fed to a conversion zone in an unagitated state in order to promote whisker growth. The conversion zone is continuously purged, preferably with an inert gas such as nitrogen. The purging gas is vented directly out of the conversion zone and carries away gaseous reaction products and impurities, prevents oxidation of the whiskers and keeps glasses from condensing and depositing on the furnace surfaces. The feed materials are fed in a dry state to the conversion zone in order to prevent erosion of the furnace walls. After conversion and cooling the whiskers are separated from the mass of particulate silicon carbide. The whiskers find use as reinforcements.

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Greer, SC, United States of America

Ronald L Beatty