Vapor deposition process and apparatus therefor

Abstract

An apparatus for depositing a ceramic coating on a component. The apparatus is configured to make use of an evaporation source containing multiple different oxide compounds, in which at least one of the oxide compounds has a vapor pressure that is higher than the remaining oxide compounds. The apparatus is operable to introduce the evaporation source into a coating chamber, suspend the component near the evaporation source, and project a high-energy beam on the evaporation source to melt and form a vapor cloud having a composition comprising the oxide compounds of the evaporation source. The apparatus includes a feature that prevents the vapor cloud from contacting and condensing on the component during an initial phase of operation, and subsequently permit and then again prevent the vapor cloud from contacting and condensing on the component during subsequent phases of operation in response to changes in the composition of the vapor cloud.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This is a continuation patent application of co-pending U.S. patent application Ser. No. 10 / 709,668 filed May 21, 2004, which is a division patent application of prior co-pending application Ser. No. 10 / 064,887 filed Aug. 27, 2002, now U.S. Pat. No. 6,790,486. The contents of these applications are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]The present invention generally relates to coating processes. More particularly, this invention is directed to a vapor deposition process and apparatus for depositing ceramic coatings containing multiple oxides with different vapor pressures using a single evaporation source containing the multiple oxides.[0003]Higher operating temperatures for gas turbine engines are continuously sought in order to increase their efficiency. However, as operating temperatures increase, the high temperature durability of the components within the hot gas path of the engine must correspondingly in...

AI Technical Summary

Benefits of technology

The invention provides a process and apparatus for depositing a ceramic coating, such as a thermal barrier coating, on components in a hostile thermal environment. The process involves using an evaporation technique with a single evaporation source containing multiple oxide compounds, where one compound has a higher vapor pressure. The apparatus prevents the vapor cloud from condensing on the component during an initial phase and allows it to contact and condense on the component during a subsequent phase when the composition of the vapor cloud changes. The invention can deposit the coating on components in a superalloy gas turbine engine, improving high temperature stability and mechanical properties.

Problems solved by technology

However, as operating temperatures increase, the high temperature durability of the components within the hot gas path of the engine must correspondingly increase.

Nonetheless, certain components of the turbine, combustor and augmentor sections of a gas turbine engine can be required to operate at temperatures at which the mechanical properties of such alloys would be insufficient.

However, the thermal conductivities of TBC materials such as YSZ are known to increase over time when subjected to the operating environment of a gas turbine engine.

Both of these solutions are undesirable for reasons relating to cost, component life and engine efficiency.

According to Rigney et al., when present in sufficient amounts these oxides are able to significantly reduce the thermal conductivity of YSZ by increasing crystallographic defects and / or lattice strains.

While the incorporation of additional oxide compounds into a YSZ TBC in accordance with Rigney et al. and Darolia et al. has made possible a more stabilized TBC microstructures, it can be difficult to deposit a TBC by an evaporation process to produce a desired and uniform composition if the additional oxide has a significantly different vapor pressure than zirconia and yttria.

However, both of these techniques complicate the deposition process such that the incorporation of additional oxides in a YSZ TBC can be difficult to perform in a commercial setting.

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