Fatigue of three advanced SiC/SiC ceramic matrix composites at 1200°C in air and in steam

Ruggles‐Wrenn, M. B.; Boucher, Nicholas; Przybyla, Craig

doi:10.1111/ijac.12773

Cited by 48 publications

(43 citation statements)

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“…SiC‐SiC CMCs must support mechanical loads at high temperatures in combustion environments and in other types of oxidizing environments that typically have steam as one of the components . Recent studies report severe degradation of high‐temperature mechanical performance of SiC‐SiC composites in steam . Hi‐Nicalon™‐S SiC fibers are used in many of these SiC‐SiC CMCs .…”

Section: Introductionmentioning

confidence: 99%

“…[7][8][9] Recent studies report severe degradation of high-temperature mechanical performance of SiC-SiC composites in steam. [10][11][12][13][14][15][16][17] Hi-Nicalon™-S SiC fibers are used in many of these SiC-SiC CMCs. 5,6 Oxidation can severely degrade SiC fiber strength, [18][19][20][21] and is therefore a vital concern for SiC-SiC CMCs, particularly in combustion environments and in steam.…”

Section: Introductionmentioning

confidence: 99%

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Static fatigue of Hi‐Nicalon™‐S fiber at elevated temperature in air, steam, and silicic acid‐saturated steam

et al. 2019

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A facility for testing SiC fiber tows in static fatigue and creep at elevated temperatures in air and steam was developed. Static fatigue of Hi‐Nicalon™‐S fibers was investigated at 800°C‐1100°C at applied stresses between 115 and 1250 MPa in air, in Si(OH)4(g)‐saturated steam, and in unsaturated steam. Fibers tested in Si(OH)4(g)‐saturated steam and in air had silica scales throughout the test sections, but those tested in unsaturated steam did not develop scales near the steam injection point. Fiber lifetimes in static fatigue were shortest in unsaturated steam, intermediate in Si(OH)4(g)‐saturated steam, and longest in air. Failure strains did not exceed 0.3%. Steady‐state strain rates and static fatigue lifetimes are modelled empirically by the Monkman‐Grant relationship. Failure mechanisms are discussed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Static fatigue of Hi‐Nicalon™‐S fiber at elevated temperature in air, steam, and silicic acid‐saturated steam

et al. 2019

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“…As the crack grows, more regions are exposed to oxidative environment, causing embrittlement. Presumably embrittled areas transfer the load to remaining intact areas, which are incapable of carrying the load leading to final failure [30,31].…”

Section: Discussionmentioning

confidence: 99%

Thermomechanical Characterization of SiC/SiC Ceramic Matrix Composites in a Combustion Facility

et al. 2019

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A combustion facility which includes uniaxial mechanical loading was implemented that enables environmental conditions more akin to jet engine environments compared to conventional static environment tests. Two types of woven SiC/SiC ceramic matrix composites (CMCs), melt-infiltrated (MI) and chemical vapor infiltrated (CVI), were subjected to fatigue loading in the combustion facility and under isothermal furnace conditions. Some CVI test coupons were coated with a multilayer environmental barrier coating (EBC) of mullite + ytterbium monosilicate using slurry infiltration process to demonstrate the performance with a coating. Combustion conditions were applied using a high velocity oxy fuel gun on the front side of the specimen and mechanical loading was applied using a horizontal hydraulic MTS machine. All the specimens considered were subjected to tension-tension fatigue loading at 100 MPa, stress ratio of 0.1 and specimen front-side surface temperature of 1200 ± 20 °C. Nondestructive evaluation (NDE) methods, such as electrical resistance (ER), was used as an in-situ health monitoring technique. Similar fatigue tests were performed in an isothermal furnace for comparison. A much lower fatigue life was observed for the uncoated specimens tested under combustion conditions in comparison to isothermal furnace condition. This difference in fatigue life was attributed to damage associated with added thermal stress due to the thermal gradient and higher rate of oxidative embrittlement due to the presence of high velocity combustion gases in the combustion environment. EBC coating increased the fatigue life in combustion environment. However, EBC coated specimens experienced spallation in the high-velocity flame due to the presence of micro cracks in the coating surface. Fracture surfaces of the failed specimens were investigated under the scanning electron microscope (SEM) to determine the extent of oxidation and damage.

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“…All tests were carried out at 1200°C using a uniaxial testing machine (MTS model 810) and a Flex Test 40 digital controller (MTS Corp.). A detailed description of the experimental arrangement is provided elsewhere 18‐20 . Standard dogbone‐shaped specimens used in this study were machined by diamond grinding.…”

Section: Materials and Experimental Arrangementsmentioning

confidence: 99%

“…Consequently, mechanical properties of the composite deteriorate and component life is reduced. In fact, recent studies reported severe deterioration of the mechanical performance of SiC/SiC composites at elevated temperature in steam 17‐21 …”

Section: Introductionmentioning

confidence: 99%

Fatigue of a SiC/SiC ceramic composite with an ytterbium‐disilicate environmental barrier coating at elevated temperature*

Ruggles‐Wrenn

Williams

2020

Int J Applied Ceramic Tech

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Tension‐tension fatigue performance of a SiC/SiC composite with an ytterbium‐disilicate environmental barrier coating (EBC) was investigated at 1200°C in air and steam. The composite is reinforced with Hi‐Nicalon™ SiC fibers and has a melt‐infiltrated matrix processed by chemical vapor infiltration of SiC with subsequent infiltration with SiC particulate slurry and molten silicon. The EBC consists of a Si bond coat and an Yb2Si2O7 top coat applied via air plasma spraying. Tensile properties were evaluated at 1200°C. Tension‐tension fatigue was examined for maximum stresses of 110‐140 MPa. To assess the efficacy of EBC, experimental results obtained for the coated composite are compared to those for a control uncoated composite. Surface grit‐blasting inherent in the EBC application process degrades tensile strength of the composite. However, the EBC effectively protects the composite from oxidation embrittlement during cyclic loading in air or steam. Fatigue runout set to 200 000 cycles (55.6 hours at a frequency of 1.0 Hz) was achieved at 110 MPa in air and steam. Retained properties of pre‐fatigued specimens were characterized. Composite microstructure, along with damage and failure mechanisms were investigated. Damage and failure of the composite are attributed to the growth of cracks originating from numerous processing defects in the composite interior.

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Fatigue of three advanced SiC/SiC ceramic matrix composites at 1200°C in air and in steam

Abstract: K E Y W O R D Sceramic-matrix composites, fatigue, fractography, high-temperature properties, mechanical properties

Cited by 48 publications

References 50 publications

Static fatigue of Hi‐Nicalon™‐S fiber at elevated temperature in air, steam, and silicic acid‐saturated steam

Static fatigue of Hi‐Nicalon™‐S fiber at elevated temperature in air, steam, and silicic acid‐saturated steam

Thermomechanical Characterization of SiC/SiC Ceramic Matrix Composites in a Combustion Facility

Fatigue of a SiC/SiC ceramic composite with an ytterbium‐disilicate environmental barrier coating at elevated temperature*

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