Project No: FE0007271
Performer: University of Pittsburgh


Contacts

Richard A. Dennis
Technology Manager, Turbines
National Energy Technology Laboratory
3610 Collins Ferry Road
P.O. Box 880
Morgantown, WV 26507-0880
304-285-4515
richard.dennis@netl.doe.gov

Steven Richardson
Project Manager
National Energy Technology Laboratory
3610 Collins Ferry Road
P.O. Box 880
Morgantown, WV 26507-0880
304-285-4185
steven.richardson@netl.doe.gov

Brian Gleeson
Principal Investigator
University of Pittsburgh
636 Benedum Hall
Pittsburgh, PA 15213-2303
412-648-1185
bgleeson@pitt.edu

Duration
Award Date:  10/01/2011
Project Date:  09/30/2014

Cost
DOE Share: $434,324.00
Performer Share: $128,378.00
Total Award Value: $562,702.00

Performer website: University of Pittsburgh - http://www.pitt.edu

Advanced Energy Systems - Hydrogen Turbines

Degradation of TBC Systems in Environments Relevant to Advanced Gas Turbines for IGCC Systems

Project Description

This University of Pittsburgh project will determine the degradation mechanisms of current state-of-the-art thermal barrier coating (TBC) in environments comprised of particulate matter and gas mixtures which are representative of gas turbines using coal-derived synthesis gas (syngas). The observed degradation processes will be used to guide the development of improved coatings for hot section components in the potentially harsh gas turbine environments in which fuels derived from coal and even perhaps biomass are burned. The unresolved complexities associated with TBC durability include enhanced attack of yttria-stabilized zirconia (YSZ) top coating by chemical reaction, physical damage of the topcoat by molten deposit penetration, and accelerated bond coat corrosion. This work is investigating how the interaction between the ash and oxidants affect TBC degradation by using lab-scale testing. Important outcomes from this study will include understanding TBC degradation; modeling integrated gasification combined cycle (IGCC) environments to develop better coatings; and extending the service life of TBCs by mitigating degradation.

This research is using the high-temperature corrosion testing facilities at the University of Pittsburgh. The deposits currently being used are based on fly ash, and accordingly, consist of calcium oxide (CaO), aluminum oxide (Al2O3), silicon dioxide (SiO2) and iron oxides (FeOx). Additions of potassium sulfate (K2SO4) and iron sulfide (FeS) are used to simulate other ash constituents. The tests are being conducted on two different TBC system types provided by Praxair Surface Technologies (PST) of Indianapolis, Indiana. PST will also conduct thermal gradient tests for assessing TBC durability with and without deposits. Both exposed and unexposed test samples are being extensively characterized using the suite of capabilities available at the University of Pittsburgh.


Free-standing YSZ coupons reacted with commercial fly ash. A thin reaction layer formed at 1200 °C, while the ash melted and severely degraded the YSZ at 1300 °C.

Free-standing YSZ coupons reacted with commercial fly ash. A thin reaction layer formed at 1200 °C, while the ash melted and severely degraded the YSZ at 1300 °C.


Program Background and Project Benefits

This project will utilize high-temperature corrosion testing facilities to determine the degradation mechanisms of current state-of-the-art thermal barrier coating (TBC) in simulated syngas environments. Turbine materials research seeks to improve coating materials that will allow for higher temperature operation and increased durability leading to increased turbine efficiency and reduced maintenance. Specifically, this project will investigate how the interaction between the ash and oxidants affect TBC degradation through enhanced attack of yttria-stabilized zirconia (YSZ) top coating by chemical reaction, physical damage of the topcoat by molten deposit penetration, and accelerated bond coat corrosion.


Accomplishments