Orthotropic Mechanical Properties of Uncoated and Ceramic-Coated Uniaxially-Compressed Carbon Cellular Porous Materials
Abstract
Porous cellular foams of moderate to high porosity (55%-95%) were investigated to determine orthotropic strength moduli and mechanical response. Uncoated porous samples consisted of reticulated vitreous carbon (RVC) rigidized by pyrolysis of flexible, open-pore organic precursor foams. The organic precursor's reference surface pore density was 100 pores-per-inch (ppi) before uniaxial compression. After compression, substrates contained 6% to 33% solid fraction, which corresponded in the thru-thickness direction to 200 ppi to 1100 ppi, respectively. Ceramic-overlaid samples were constructed by depositing silicon carbide (SiC) via chemical vapor infiltration (CVI) onto 600 ppi and 1000 ppi RVC substrates. The ceramic overlays added solid fractions of 5% and 12%, respectively. Compressive and tensile strengths were measured in-plane and thru-thickness for all materials. Results showed compressive crush strengths of the multi-layer porous materials to be bounded between theoretical strengths of solid RVC substrate and SiC-coated materials. Predictions from currently accepted cell anisotropy relations were compared to experiment and are shown to greatly over-predict the orthotropy due to uniaxial compression. The data may be applied to allow more precise design of components using ceramic-coated porous cellular materials.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 15, 2001
- Accession Number
- ADA408549
Entities
People
- David Barland
Organizations
- Air Force Research Laboratory