Please click Additional Files below to see the full abstrac

Detwiler, Kaitlin

Hunt, Reece

Opila, Elizabeth

English

Engineering Conferences International

MICRO-SCALE OBSERVATION OF CRACKING IN SIC/BN/SIC CERAMIC MATRIX COMPOSITES  Kaitlin Detwiler, Air Force Research Laboratory, USA kaitlin.detwiler.4@us.af.mil Reece Hunt, University of Dayton Research Institute, USA Elizabeth Opila, University of Virginia, USA   Key Words: ceramic matrix composites, micro-scale testing  SiC/BN/SiC ceramic matrix composites (CMCs) will be exposed to both mechanical loads and oxidants during high-temperature service conditions.  Stresses may cause micro-cracking in the CMC, allowing pathways for oxidant ingress into the CMC.  The surface crack opening displacement (COD) is a key variable in predicting the CMC oxidation and lifetime behavior [1].  In order to supplement CMC oxidation damage modeling, experimental measurements of CODs are required.  A tensile stage was used with light and scanning electron microscopy (SEM) to evaluate micro-cracking under tensile load in a SiC/BN/SiC CMC.  The SiC/BN/SiC was provided by Rolls-Royce and consists of Hi-Nicalon fibers, a BN interphase, a CVI layer, and SiC particles plus melt infiltrated silicon.  Micro-crack spacing and crack composition, a novel measurement introduced in this work, were measured from light microscopy images taken at room temperature.  Crack spacing decreased with increasing load, with a majority of cracks in contact with BN fiber coatings.  COD was measured at room and elevated temperature (600ºC). An example of increasing COD with load at 600°C is imaged in Figure 1.  CODs increased nearly linearly with increased load.  CODs were also related to local microstructure, with CODs being wider in the melt-infiltrated matrix material than in transverse fiber tows.  The results of this study will be compared to micro-crack spacing models and will also be discussed in context of CMC oxidation mechanisms and models.    Figure 1 – Secondary SEM images of micro-crack in a SiC/BN/SiC CMC at increasing stress levels at 600°C showing increasing COD with applied load.  Loading direction is horizontal.    References [1] Parthasarathy, T. A., Cox, B., Sudre, O., Przybyla, C., & Cinibulk, M. K. (2018). Modeling environmentally induced property degradation of SiC/BN/SiC ceramic matrix composites. Journal of the American Ceramic Society, 101(3), 973-997.  

Micro-scale observation of cracking in SiC/BN/SiC ceramic matrix composites

https://dc.engconfintl.org/cgi/viewcontent.cgi?filename=0&article=1028&context=cmcii&type=additional

Micro-scale observation of cracking in SiC/BN/SiC ceramic matrix composites

Abstract

Similar works

Full text

Available Versions

Engineering Conferences International