United Technologies Corporation

Kenneth E Taylor

David A Rutz

Robert P Schaefer

Martin J Reiner

Walter F Gustafson

An abrasive, wear resistant layer is applied to the tip surface of a superalloy gas turbine blade by high temperature sintering operation which produces a high strength bond between the layer and the blade, minimizes gamma prime phase growth, and prevents recrystallization in the blade. Important features of the invention include removing plastic strain damage from the tip surface prior to the sintering operation, using induction heating techniques to sinter a layer of metal powder particles and ceramic particulates to the blade tip surface, and shielding the airfoil and root portion of the blade from the radiant heating source during the sintering operation while at the same time, conductively removing heat from the blade.

Method for making a turbine blade having a wear resistant layer sintered

Directional solidification of a single crystal superalloy article may be accomplished using a mold with a starter section, and a selector section to convert columnar growth from the starter into single crystal growth. In such a process, the deviation of [001] crystallographic orientation with respect to the longitudinal axis of the article being formed is reduced from 9 degrees to 5 degrees by controlling the heat transfer in the starter section. A stepped starter section, wherein the lower subsection has a volume of 52-98% of the total starter volume, and wherein the upper subsection is relatively small in lateral dimension, has been found most useful. When the solidification interface moves into the smaller width upper subsection, it becomes more nearly planar, and results in improved columnar growth in the starter, and in reduction in the crystallographic deviation of the article.

Mold with starter and selector sections for directional solidification

Apparatus for casting directionally solidified articles is disclosed. Concepts for obtaining a desired temperature profile in an induction furnace are discussed. An induction furnace 10 has increased heating capacity at the withdrawal end 32 of the susceptor 28. A hot zone baffle 42 is disposed at the withdrawal end to inhibit the radiation of heat energy from the hot zone 12. A plurality of grooves 34 are formed about the interior of the susceptor at the withdrawal end to inhibit the conduction of heat energy out of the susceptor. A preferred thermal profile in the operating furnace with a peak temperature in close proximity to the withdrawal end results.

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Longmeadow, MA, United States of America

Kenneth E Taylor