Session: 18-07 Metallurgy, Coating and Repair III

Paper Number: 127899

127899 - Durability Test of Advanced TBC’s 

This paper reports the first results for the durability test of advanced TBC’s which is one of EPRI Low-Carbon Resources Initiative (LCRI) projects. Reasons for this project are:

·       Decarbonization of power generation will increase hydrogen as fuel for gas turbines. Issues using hydrogen only as fuel will increase flame speed, temperature, quenching distance, steam in combustion products (from 10% to 16%) and loading.

·       This will increase erosion and heat transfer to base materials and coatings and the durability of Thermal Barrier Coating (TBC) is questioned by several.

·       Higher surface temperature of the TBC can create a phase change of the coating from the optimal tetragonal (higher bend strength, fracture toughness and thermal shock resistance) to cubic and monoclinic (volume change creating stresses and spallation).

·       Alternative stabilizers such as CeO2, Sc2O3 and TiO2 can be used (so called low K TBC) to increase stabilization of the conventical (Y TBC) yttria stabilized zirconia.

·       MCrAlY bond coat is applied between TBC top coat and base material to increase the adhesion and oxidation resistance. Note: A higher temperature will increase oxidation and spallation of the TBC.

 

In November 8, 2022 Stage 1 Buckets (S1B) with 12 different types of Thermal Barrier Coatings (TBC) were installed in Dominion Chesterfield Frame 7F .03 gas turbine. Operation parameters: MNQC combustion system, firing at 2350°F with steam injection of 100,000 pounds per hour resulting in hot gas H₂O concentration comparable to as high percentage H₂, 80%+ hydrogen fuel burned in a in a DLN combustion system.

TBC types:          Three (3) conventional and Dense Vertical Cracked Yttria stabilized Zirconia’s (DVC TBC’s)                           Eight (8) low K and combination DVC and rare earth stabilized Zirconia’s (low K TBC’s)                            One (1) Dense Vertical cracked Metallurgy Yttria stabilized Zirconia (DVM TBC) 

The DVC and low K TBC’s were applied by seven (7) different coating vendors (APG, CTS, Doosan, Honeywell, Liburdi, MD&A and Sulzer) and DVM TBC by the OEM (GE). This paper will present the first semi-annual borescope inspections as well as thermal conductivity and phase analyses of Yttrium and low K TBC coatings in as sprayed condition and after sintering for 400 hours at 1000⁰C, 1200⁰C and 1400⁰C (last one in progress).

Presenting Author: John Scheibel EPRI

Presenting Author Biography: John, need to add this later

Authors:

Hans Van Esch TEServices
Stijn Pietersen TEServices
John Scheibel EPRI
Olaf Barth Dominion