Howmet Research Corporation

Ronald James Keller

Rodney S Haaland

Julie A Faison

Gregory R Frank

Charles F Caccavale

Xi Yang

Alfred P Kaulius, Jr

A method of forming a ceramic investment shell mold about a fugitive wax pattern of an article comprises coating the pattern with ceramic slurry, applying a ceramic particulate material heated above ambient temperature to the slurry layer, drying the ceramic slurry layer with ceramic particulates thereon, and repeating said coating, applying and drying steps to build up a shell mold on the pattern. The ceramic slurry with ceramic particulates thereon is dried initially dried for a time using relatively low humidity flowing air at an air temperature above about 80 degrees F. and then subsequently for a time using relatively low humidity flowing air at an air temperature not exceeding about 80 degrees F. Ceramic investment shell molds can be built-up in times typically less than 10 hours by practice of the invention with substantially reduced incidence of shell mold cracking during the shell mold building process and subsequent pattern removal operation.

Method of making investment casting molds

Method of making a ceramic core for casting an industrial gas turbine engine airfoil having a large airfoil pitch by forming a precursor core (chill) of smaller dimensions than the final desired ceramic core, firing the chill, applying a thin ceramic skin to the fired chill to form a coated core of final dimensions, and then firing the coated core. Firing of the thin ceramic skin reduces airfoil pitch shrinkage resulting from the latter firing operation to reduce overall core dimensional tolerance variations.

Ceramic core and method of making

An impregnated fired porous alumina-based ceramic core for use in an investment shell mold in the casting of molten metals and alloys wherein the core is impregnated with yttria to improve core creep resistance at elevated casting temperatures and times.

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Grand Haven, MI, United States of America

Ronald James Keller