H E. Eaton, G D. Linsey /Journal of the European Cere ieny22(2002)274}-2747 Thermal sprayed BSAS EBC tends to crack and spall from large position of amorphous structure(likely CTE mismatc 000°cto1100° in situ heat treatment used to solve amorphou 二 e X-ray scans of surface of BsAS EBC vs heat treat In situ heat treat at 1 100%C eliminates minutes no amorphous phase 5 minutes- amorphous erystalline Fig. 9. Thermal spray processing of BSAS at high temperature produces crystalline structure(see Ref. 22) BSAS EBC system successfully demonstrated on engine components and in engine Ist generatlon BSAS EBC applied to Solar Turbines Centaur 50S SIC CMC combustion Un iksm图 tested for 13,937 hrs at Bakersfield, CA and more than 14,000 bn to date in Lawrence, MA Ist generation EBC provides >3x improvement in life vs uncoated 2nd generation EBC expected to achleve 30,000 hr llfe. HSAS 50 mm by 200mm outer SiC CMC liner and 330 200 mm inner SiC CMc liner coated with BSAS CmC Solar Turbines Centaur 50S engine test in Bakersfield, CA Fig. 10. BSAS EBC system successfully applied to SiC CMC (see Ref. 20). exhibit thermal barrier properties as well as environ- diameter for the outer liner and 330 mm diameter for mental barrier protection the inner liner To date these liners have received almost t Fig. g shows the phase content of thermal sprayed 30,000 h total testing with the longest test being 13,937 sas versus time at temperature after depositing the h. Improvement in life of an EBC coated component BSAS onto the Sic substrate held at elevated tempera- versus an uncoated component is at least 3x based during deposition process. As fabricated the this engine testing BSAS exhibits an amorphous structure which on large surfaces tends to crack when first heat treated. Holding the substrate at a temperature of between 1000 and 1 100C for a period of time prior to first cooling to RT after thermal spraying results in a crystalline structure Accelerated"oxidation of SiC in a high temperature which is stable to post coating heat treatment high steam environment is now well documented by Fig. 10 shows the BsAs coating system. The system experiments, engine testing, and modeling. Current consists of a silicon metal bond coat followed by a mixed understanding of the problem and development of Sic layer of mullite and BSAS with a top layer of BSAs. The technology leads one to the conclusion that long life use system has been successfully applied to SiC CMC com- of SiC in gas turbine engines requires an environmental bustion liners for a Solar Turbines, Inc. industrial gas barrier coating to provide protection for SiC. Environ- turbine engine. In this case the liners were 760 mm in mental barrier coatings for SiC have been developedexhibit thermal barrier properties as well as environ￾mental barrier protection. Fig. 9 shows the phase content of thermal sprayed BSAS versus time at temperature after depositing the BSAS onto the SiC substrate held at elevated tempera￾ture during the deposition process. As fabricated the BSAS exhibits an amorphous structure which on large surfaces tends to crack when first heat treated. Holding the substrate at a temperature of between 1000 and 1100
C for a period of time prior to first cooling to RT after thermal spraying results in a crystalline structure which is stable to post coating heat treatment. Fig. 10 shows the BSAS coating system. The system consists of a silicon metal bond coat followed by a mixed layer of mullite and BSAS with a top layer of BSAS. The system has been successfully applied to SiC CMC com￾bustion liners for a Solar Turbines, Inc. industrial gas turbine engine. In this case the liners were 760 mm in diameter for the outer liner and 330 mm diameter for the inner liner. To date these liners have received almost 30,000 h total testing with the longest test being 13,937 h. Improvement in life of an EBC coated component versus an uncoated component is at least 3 based on this engine testing. 3. Summary ‘‘Accelerated’’ oxidation of SiC in a high temperature, high steam environment is now well documented by experiments, engine testing, and modeling. Current understanding of the problem and development of SiC technology leads one to the conclusion that long life use of SiC in gas turbine engines requires an environmental barrier coating to provide protection for SiC. Environ￾mental barrier coatings for SiC have been developed, Fig. 9. Thermal spray processing of BSAS at high temperature produces crystalline structure (see Ref. 22). Fig. 10. BSAS EBC system successfully applied to SiC CMC (see Ref. 20). 2746 H.E. Eaton, G.D. Linsey/ Journal of the European Ceramic Society 22 (2002) 2741–2747