Methods for fabricating shapes by use of organometallic ceramic precursor binders
First Claim
1. A process for fabricating shaped articles by casting comprising:
- at least partially coating the surface of at least one sand with at least one hardenable, solventless liquid, organometallic, ceramic precursor binder comprising a material selected from the group consisting of polysilazane, polyureasilazane, polythioureasilazane and polysiloxane to form a sand/binder mixture;
forming at least one shape from said sand/binder mixture;
hardening said sand/binder mixture by a crosslinking mechanism to form at least one sand mold, shell, or core; and
casting at least one metal or metal matrix composite into the resulting hardened at least one sand mold, shell, or core to form at least one shaped metal or metal matrix composite article.
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Abstract
This invention relates to the discovery of organometallic ceramic precursor binders used to fabricate shaped bodies by different techniques. Exemplary shape making techniques which utilize hardenable, liquid, organometallic, ceramic precursor binders include the fabrication of negatives of parts to be made (e.g., sand molds and sand cores for metalcasting, etc.), as well as utilizing ceramic precursor binders to make shapes directly (e.g., brake shoes, brake pads, clutch parts, grinding wheels, polymer concrete, refractory patches and liners, etc.). In a preferred embodiment, this invention relates to thermosettable, liquid ceramic precursors which provide suitable-strength sand molds sand cores at very low binder levels and which, upon exposure to molten metalcasting exhibit low emissions toxicity as a result of their high char yields of ceramic upon exposure to heat.
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Citations
24 Claims
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1. A process for fabricating shaped articles by casting comprising:
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at least partially coating the surface of at least one sand with at least one hardenable, solventless liquid, organometallic, ceramic precursor binder comprising a material selected from the group consisting of polysilazane, polyureasilazane, polythioureasilazane and polysiloxane to form a sand/binder mixture; forming at least one shape from said sand/binder mixture; hardening said sand/binder mixture by a crosslinking mechanism to form at least one sand mold, shell, or core; and casting at least one metal or metal matrix composite into the resulting hardened at least one sand mold, shell, or core to form at least one shaped metal or metal matrix composite article.
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- 2. A sand/binder mixture comprising (1) at least one sand and (2) at least one at least one hardenable, solventless liquid, organometallic, ceramic precursor binder, said binder comprising at least one metal-carbon bond, at least partially coated on the surface of said at least one sand characterized in that said sand/binder mixture is hardenable by a crosslinking mechanism.
- 4. A process for fabricating shaped articles by casting, said process comprising (1) at least partially coating the surface of at least one sand with at least one hardenable, solventless liquid, organometallic ceramic precursor binder, said binder comprising at least one metal-carbon bond, to form a sand/binder mixture, (2) forming at least one shape from said sand/binder mixture, characterized by hardening said sand/binder mixture by a crosslinking mechanism to form at least one sand mold, shell, or core, and (3) casting at least one metal or metal matrix composite into the resulting hardened at least one sand mold, shell, or core to form at least one shaped metal or metal matrix composite article.
Specification