Combustion Turbine Hot Section Coating Life Management COATLIFE for Advanced Metallic Coatings and TBCs 1011593 Combustion Turbine Hot Section Coating Life Management COATLIFE for Advanced Metallic Coatings and TBCs 1011593 Technical Update, March 2005 Cosponsor U.S Department of Energy National Energy Technology Laboratory 626 Cochrans Mill Road Pittsburg, PA 15236-0949 EPRI Project Managers D Gandy J Scheibel Electric Power Research Institute • 3412 Hillview Avenue, Palo Alto, California 94304 • PO Box 10412, Palo Alto, California 94303 • USA 800.313.3774 • 650.855.2121 • askepri@epri.com • www.epri.com DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITIES THIS DOCUMENT WAS PREPARED BY THE ORGANIZATION(S) NAMED BELOW AS AN ACCOUNT OF WORK SPONSORED OR COSPONSORED BY THE ELECTRIC POWER RESEARCH INSTITUTE, INC (EPRI) NEITHER EPRI, ANY MEMBER OF EPRI, ANY COSPONSOR, THE ORGANIZATION(S) BELOW, NOR ANY PERSON ACTING ON BEHALF OF ANY OF THEM: (A) MAKES ANY WARRANTY OR REPRESENTATION WHATSOEVER, EXPRESS OR IMPLIED, (I) WITH RESPECT TO THE USE OF ANY INFORMATION, APPARATUS, METHOD, PROCESS, OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT, INCLUDING MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, OR (II) THAT SUCH USE DOES NOT INFRINGE ON OR INTERFERE WITH PRIVATELY OWNED RIGHTS, INCLUDING ANY PARTY'S INTELLECTUAL PROPERTY, OR (III) THAT THIS DOCUMENT IS SUITABLE TO ANY PARTICULAR USER'S CIRCUMSTANCE; OR (B) ASSUMES RESPONSIBILITY FOR ANY DAMAGES OR OTHER LIABILITY WHATSOEVER (INCLUDING ANY CONSEQUENTIAL DAMAGES, EVEN IF EPRI OR ANY EPRI REPRESENTATIVE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES) RESULTING FROM YOUR SELECTION OR USE OF THIS DOCUMENT OR ANY INFORMATION, APPARATUS, METHOD, PROCESS, OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT ORGANIZATION(S) THAT PREPARED THIS DOCUMENT Southwest Research Institute This is an EPRI Technical Update report A Technical Update report is intended as an informal report of continuing research, a meeting, or a topical study It is not a final EPRI technical report ORDERING INFORMATION Requests for copies of this report should be directed to EPRI Orders and Conferences, 1355 Willow Way, Suite 278, Concord, CA 94520, (800) 313-3774, press or internally x5379, (925) 609-9169, (925) 609-1310 (fax) Electric Power Research Institute and EPRI are registered service marks of the Electric Power Research Institute, Inc Copyright © 2005 Electric Power Research Institute, Inc All rights reserved CITATIONS This report was prepared by: Southwest Research Institute 6220 Culebra Road San Antonio, TX 78238-5166 Principal Investigators N Cheruvu K Chan This report describes research sponsored by the Electric Power Research Institute (EPRI) and the U.S Department of Energy The report is a corporate document that should be cited in the literature in the following manner: Combustion Turbine Hot Section Coating Life Management: COATLIFE for Advanced Metallic Coating and TBCs, EPRI, Palo Alto, CA, and U.S Department of Energy, Pittsburg, PA: 2005 1011593 iii REPORT SUMMARY COATLIFE is a coating life model that predicts the oxidation life of overlay and diffusion coatings The purpose of this project was to enhance the capability of COATLIFE to handle spallation life prediction for thermal barrier coatings (TBCs) that are being used in advanced turbines manufactured by major domestic OEMs, and to broaden COATLIFE capability to cover a broader range of MCrAlY coatings for oxidation and thermomechanical fatigue (TMF) life prediction of turbine blades Background COATLIFE has been designed to predict the oxidation life of combustion turbine coatings and TMF life of coated blade alloys under variable plant operation conditions The algorithms in COATLIFE take into account all the degradation mechanisms involved during long-term service of the coated blades and TMF life of the blades The specific physical degradation mechanisms considered in the model include oxide formation kinetics, spallation of the protective oxide (Al2O3 layer), and interdiffusion of aluminum from the coating into the superalloy blade substrate This approach can account for the contribution of time in service, number of startup and shutdown cycles, and variable temperature operation (that is, part load operation) Equipment manufacturers also commonly use two other coatings on the blades and vanes of current engines of advanced turbines: NiCoCrAlY and CoNiCrAlY These coatings are similar in composition; General Electric uses NiCoCrAlY (GT33), and Siemens-Westinghouse uses CoNiCrAlY (trade name CT102) In order to be more effective, the COATLIFE code needed to be enhanced to handle these widely used coatings Objectives • To develop the capability of COATLIFE to handle spallation life prediction for TBCs that are being used in advanced turbines manufactured by major domestic OEMs • To enhance COATLIFE to cover a broader range of MCrAlY coatings for oxidation life prediction • To validate the predictive capabilities of COATLIFE and provide the required metallurgical data to correlate eddy current NDE results obtained on service-run blades v Approach The MCrAlY coating selected for the evaluation was CT102 Siemens-Westinghouse uses this coating on combustion turbine (CT) turbine blades and vanes The chemical composition of CT102 coating is similar to the nominal chemistry of GE’s proprietary NiCoCrAlY coating GT33, which is used on the blades of GE’s F, G, and H class turbines Cyclic oxidation tests were conducted on the NiCoCrAlY-coated specimens Coating life diagrams for the coating were computed as a function of temperature Isothermal oxidation tests at three temperatures were conducted on the TBC-coated GTD-111 and IN-738 specimens with or without a platinum interlayer between the bond coating and TBC with or without a platinum interlayer between the bond coating and TBC Thermal cycling tests were also conducted at two peak temperatures on the TBC-coated GTD-111 and IN-738 specimens with two coatings to determine the constants for COATLIFE model Isothermal oxidation tests on the TBC-coated specimens were performed at three different temperatures: 1850°F (1010°C), 1900°F (1038°C), and 1950°F (1066°C) Cyclic oxidation testing of the TBC-coated specimens was performed at the two peak temperatures of 1950°F (1066°C) and 1850°F (1010°C) Results Thermally grown oxide (TGO) thickness between the bond coat and the TBC was determined to be a function of time and temperature for four bond coat/substrate systems Oxidation life and TMF life equations for the NiCoCrAlY coating have been incorporated in COATLIFE 4.0 In addition, the graphical user interface (GUI) was revised to allow NDE input of aluminum content and/or volume percent of the beta phase for computation of coating life using the NDE data A model for TBC life was developed, and the constants for the model were determined from the long-term testing of the TBC-coated GTD-111 and IN-738 materials The TBC life model was validated with the laboratory data that have not been used to determine the model constants The TBC life equations have been incorporated into an upgraded version of the COATLIFE software EPRI Perspective Performance and durability of coating systems are prime life-limiting factors for hot section components Turbine blades are the most critical and expensive parts of these components because the reliability and availability of a turbine often depends on blade life, which depends on the coating life A reliable method for more accurately predicting the life of all coatings commonly in use today is crucial to assessing and extending blade service life Keywords Gas turbines Thermal barrier coatings Turbine life management Life assessment Turbine blades Thermomechanical fatigue vi ABSTRACT The objective of this task was to enhance the capability of COATLIFE to handle spallation life prediction for thermal barrier coatings (TBCs) that are used in advanced turbines manufactured by major domestic OEMs, and to broaden COATLIFE capability to cover a broader range of MCrAlY coatings for oxidation and thermomechanical fatigue (TMF) life prediction of turbine blades Cyclic oxidation and isothermal exposure tests have been conducted on the TBC-coated and MCrAlY-coated specimens to generate constants for the COATLIFE model Thermally grown oxide (TGO) thickness between the bond coat and the TBC has been determined as a function of time and temperature for four bond coat/substrate systems Oxidation life and TMF life equations for the NiCoCrAlY (similar to GE’s GT33) coating have been incorporated in COATLIFE 3.0 In addition, the graphical user interface (GUI) was revised to allow NDE input of aluminum content and/or volume percent of the beta phase for computation of coating life using the NDE data The software has been upgraded to COATLIFE 3.5 A model for TBC life has been developed, and the constants for the model are determined from the long-term testing of the TBC-coated GTD-111 and IN-738 materials The TBC life model was validated with the laboratory data that have not been used to determine the model constants The TBC life equations have been incorporated into an upgraded COATLIFE 4.0 software, and a users manual for COATLIFE 4.0 has been prepared vii ... Combustion Turbine Hot Section Coating Life Management COATLIFE for Advanced Metallic Coatings and TBCs 1011593 Technical Update, March 2005... be cited in the literature in the following manner: Combustion Turbine Hot Section Coating Life Management: COATLIFE for Advanced Metallic Coating and TBCs, EPRI, Palo Alto, CA, and U.S Department... thermomechanical fatigue (TMF) life prediction of turbine blades Background COATLIFE has been designed to predict the oxidation life of combustion turbine coatings and TMF life of coated blade alloys