SBIR-STTR Award

TA&T proposes to develop and demonstrate a multi-layer based EBC that exhibits exceptional resistance to both the water vapor laded combustion environment of turbine engines and the external operational environments of molten sand ingestion at 1400oC. Several variants of experimental EBC compositions will be explored based on magnetron sputtered, multilayer hafnium oxide systems with excellent phase stability. Chemical resistance top coats will also be applied. A systematic approach includes the following: deposition on SiC CMC substrates, comprehensive characterization methods-XRD, SEM, EDS-to optimize deposition conditions, coating chemistry and microstructure; elevated isothermal and thermal cycling tests of EBC coated SiC CMC coupons in a 50/50 air/water vapor environment with sand; hot combustion tests of EBC coated SiC CMC bars with sand ingestion to determine and compare their potential for an accelerated Phase 2 program.

Graded rare earth hafnia multilayer coatings with three different top layer compositions will be deposited on SiC CMC and alumina substrates, characterized by XRD, SEM and EDS, and subjectedtoflowing air-steam at 50% relative humidity without and with CMAS in both isothermal and thermal cycling conditions.Post test analyses include weight change, SEM microstructure characterization changes, XRD/EDS chemical changes to determine and compare the effectiveness of the graded EBC compositions to protect the SiC CMC substrates. DSC/TGA analysis will be used to compare thermal properties of AFRL-03 and synthetic CMAS and correlate with possible differences in CMAS reactions with graded rare earth hafnia multilayer coatings.Coated buttons and bars will be provided to ARL and Honeywell for independent tests in laboratory scale and burner rig combustion-CMAS environments. ---------- The goal of the U.S. Army, Air Force, Navy, Marines, commercial aviation and industrial power plants to develop gas turbines capable of reliable operation at turbine inlet temperatures up to 3100oF. Consequently, there is a driving need to extend the capability of SiC CMCs and/or related Ceramic CMCs and associated thermal—environmental barrier coatings (T-EBCs) to resist degradation in harsh moisture laded combustion and sand/dust ingestion (CMAS) conditions at much higher temperatures than GE’s current state of the art 2400oF. In Phase 1, Technology Assessment and Transfer (TA&T) demonstrated that graded HfC-SiC matrix CMC samples densified by TA&T’s rapid GP-RTG CVI process and coated with TA&T’s Yb Hafnia multilayer T-EBC provided excellent protection capabilities in combined moisture-CMAS environments at 1550oC (2822oF). In Phase 2 Technology Assessment and Transfer (TA&T) proposes to optimize the CVI and/or CVI-PIP densification process and associated microstructures of the graded HfC-SiC CMCs. In parallel, TA&T will develop and optimize dual layer plasma spray Yttria Stabilized Zirconia-magnetron sputtered Yb Hafnia multilayer T-EBCs based on laboratory scale high humidity-CMAS testing. As a subcontractor Brayton Energy proposes a comprehensive approach to design, build and test an advanced, subscale CMC combustor for a medium lift helicopter engine. Brayton will in steps, use its proprietary software and CFD analysis to optimize a medium powered turboshaft helicopter combustor design and refined subscale CMC combustor test article design and complete their effort with a combustor instrumentation, test plan and analysis and comparison of combustor results from the High Particulate Ingestion Rig test with modeling predictions. TA&T will apply the optimized CMC densification and dual layer plasma spray YSZ-sputtered Yb Hafnia multilayer T-EBCs protocols to subscale combustor test article and send to ARL Aberdeen for test and evaluation. All the experimental details, results, analysis and recommendations for follow on scale up will be documented in a Final Report. An attractive near-term commercialization approach is also defined.