Gm Global Technolgoy Operations, Inc.

Nicholas Edward Sargent

Mei Cai

June-Sang Siak

Thomas C Pederson

Sheila Farrokhalaee Kia

Richard M Schreck

Sand mold for shaping molten metal cast into the mold. The mold includes sand, a thermally oxidizable polymer amongst the grains of the sand, and a catalyst coating on the gains for promoting the thermal oxidation and breakdown of the polymer in the course of removing the sand from the casting and/or reclaiming the sand for reuse. The catalyst coating adheres so tenaciously to the grains of sand that the sand can withstand repeated casting and sand reclamation cycles without the need to replenish the catalyst.

Foundry sand with oxidation promoter

In the lost foam casting of aluminum, coating a fugitive pattern with a refractory coating containing a thermally stable, water-insoluble, acid-gasifiable (e.g. CaCO) compound, and contacting the casting, with the coating thereon, with an acid to dissociate and gasify the compound and rupture the coating. Preferably, any thermal degradation products from the pattern residing in the coating are neutralized to promote wetting of the coating.

Removing lost foam pattern coating residue from a casting

Coating foundry sand with a thin layer of an oxidation-promoting catalyst. Preferred catalysts comprise ferric and cupric oxides. The catalysts promote the oxidation of any polymeric binder or residues admixed with the sand. The sand is coated by wetting the grains with a solution of a catalyst precursor, drying the sand and baking the sand in air to convert the precursor to the catalyst.

A mold for a prototype metal casting or the like may advantageously be made by forming a casting pattern of adhesively bonded aggregate particles using a binder containing a principle constituent that is soluble in supercritical carbon dioxide; forming a rigid shell mold about the pattern of materials that are unaffected by supercritical carbon dioxide; thereafter exposing the pattern and mold combination to supercritical carbon dioxide to remove the pattern binder adhesive and leave unbonded aggregate particles in the mold and removing the aggregate particles from the mold to leave a mold cavity that faithfully defines the pattern shape.

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Canton, MI, United States of America

Nicholas Edward Sargent