Howmet Research Corporation

Howmet Corporation

Julie A Faison

Rodney S Haaland

Ronald James Keller

Robert E Grunstra

Eliot S Lassow

Neil E Paton

Thomas J Thornton

Jacqueline B Wahl

David L Squier

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

A ceramic core that includes, prior to core sintering, erbia filler material alone or admixed with a second ceramic filler material, such as alumina, and a binder to provide a core that is relatively non-reactive with superalloys used in the manufacture of turbine blades, dimensionally stable during directional solidification (DS) for extended times, removable by chemcial leaching techniques, and having enhanced X-ray detectable during post-cast inspection operations. After core sintering, the ceramic core has a microstructure comprising an erbia-alumina garnet phase and an unreacted ceramic filler phase (e.g. alumina).

Erbia-bearing core

A method of making a single crystal or columnar grain superalloy casting comprises casting a superalloy in a mold wherein at least one of the mold and optional core comprises an oxygen-bearing ceramic, directionally solidifying the superalloy to form a single crystal or columnar grain superalloy casting, and solution heat treating the superalloy casting. The heat treatment is conducted under an atmosphere including a carbon-bearing gas, such as a carbon monoxide and inert gas mixture, wherein the carbon-bearing gas is present in an effective amount to reduce loss of carbon from the casting during the heat treatment. The heat treatment can be conducted prior to removal of all of the mold and core, if present, such as, for example, when the cast mold is in the as-knocked out condition wherein residual mold and/or core material is present on the casting. Alternately, the heat treatment can be conducted after removal of the mold and core, if present.

Heat treatment of superalloy casting with partial mold removal

A method of removing ceramic material, such as for example a ceramic core, from a metallic cast or other component involves contacting the metallic cast component and a caustic ceramic leaching medium at elevated temperature for a time effective to substantially remove the ceramic material from the component and providing an oxygen getter in the caustic ceramic leaching medium in an amount effective to avoid deleterious surface corrosion of the component while the ceramic material is being removed therefrom.

Growing community of inventors

Whitehall, MI, United States of America

Julie A Faison