Abstract
To understand the failure mechanism or to predict the spallation life of environmental barrier coatings (EBC) on fiber reinforced ceramic matrix composites, the fracture strength of EBC and the process of the crack growth in EBC layers need to be experimentally determined under standard or simulated engine operating conditions. The current work considers a multi layered barium strontium aluminum silicate (BSAS)-based EBC-coated, melt infiltrated silicon carbide fiber reinforced silicon carbide matrix composite (MI SiC/SiC) specimen that was tensile tested at room temperature. Numerous tests were performed under tensile loading conditions, and the specimen was loaded until failure under pre-determined stress levels. The specimen was examined with optical microscopy, scanning electron microscopy (SEM), computed tomography (CT) scan, and digital image correlation (DIC) camera. Observation from the computed tomography scanning, the SEM, and the optical microscopy did not offer conclusive information concerning the cracks that spawned during the tests. However, inspection with the DIC camera offered some indication that cracks had developed and allowed their detection and the location of their initiation site. Thus, this study provides detailed discussion of the results obtained from the experimental investigation and the nondestructive evaluation (NDE), and it also includes assessment of the stress response predicted by analytical modeling and their impact on EBC durability and crack growth formation under complex loading settings.
Highlights
Ceramic matrix composite (CMC) materials such as (SiC/SiC) are becoming highly attractive to aero engine makers, making them prime candidates for use in turbine engines, in the hot section part [1]
They hold unique characteristics and suitable properties, such as being light weight and can operate in high temperature environments—typically 200 ◦ C higher than conventional superalloys. These are considered to be great advantages for the turbine engine manufacturer, since they will lead to much needed higher fuel efficiency and durability. For these CMCs to perform in harsh environments—especially where high temperature and moisture are present—they have to be coated with a protective coating, such as silica
The silica dissociates, causing recession of the substrate [2]. Such scenarios have led to the development of multilayered environmental barrier coatings (EBC) that can operate efficiently at high temperatures up to 1450 ◦ C, while a newer set of advanced coatings are being developed for much higher temperature applications [3,4,5,6]
Summary
Ceramic matrix composite (CMC) materials such as (SiC/SiC) are becoming highly attractive to aero engine makers, making them prime candidates for use in turbine engines, in the hot section part [1] They hold unique characteristics and suitable properties, such as being light weight and can operate in high temperature environments—typically 200 ◦ C higher than conventional superalloys. These are considered to be great advantages for the turbine engine manufacturer, since they will lead to much needed higher fuel efficiency and durability For these CMCs to perform in harsh environments—especially where high temperature and moisture are present—they have to be coated with a protective coating, such as silica. The EBC recesses during engine operating conditions, but at a lower
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