Alliedsignal Inc.

John P Pollinger

Jean Yamanis

Chien-Wei Li

Stephen C Danforth

Philip J Whalen

Vikram Ramesh Jamalabad

Mukesh Agarwala

Jeffrey A Goldacker

A ceramic component is manufactured rapidly using a mold made directly from a solid freeform manufacturing process. Solid freeform fabrication, or rapid prototyping, procedures are used to generate molds of materials that are soluble or otherwise fugitive. A gel casting suspension containing ceramic and emulsifying agents is poured into the cavity of the mold and caused to set. The mold is then removed by dissolution or heat treatment, leaving intact the gelcast part. Conventional procedures are then utilized to densify the gelcast component to the required final component. Time consuming and expensive machine tooling procedures are virtually eliminated. Ceramic components are generated rapidly in a cost effective manner.

Gel cast molding with fugitive molds

A silicon nitride sintered body has a composition consisting essentially of 80 to 93% by weight .beta. silicon nitride, 7 to 20% by weight grain boundary phases consisting essentially of (i) at least two rare earth elements, wherein yttrium is considered a rare earth, and strontium which, calculated as SrO, is 0.5 to 5% by weight, and (ii) at least two of Si, N, O and C; and (c) silicon carbide particulate present in the amount of about 5 to 35 parts by weight per 100 parts by weight of components (a) and (b), said SiC being substantially homogeneously dispersed within said sintered body. Such a ceramic has high strength and long term durability, and is especially suited for industrial applications such as components for gas turbine and automotive engines.

Gas pressure sintered silicon nitride having high strength and stress

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Redondo Beach, CA, United States of America

John P Pollinger