Session: 17-15-01: Society-Wide Micro/Nano Poster Forum

Paper Number: 99126

99126 - Fabrication and Testing of Polymer-Derived Non-Oxide Ceramic Matrix Composite Materials 

Ceramic matrix composites (CMCs) are suitable candidates for aerospace and aircraft components due to the composites’ lightweight structure, high mechanical strength, and high temperature stability. Compared to the more traditionally used polymer matrix composite (PMC), CMCs have shown much higher mechanical stability and strength at high temperatures. This is mainly due to the presence of nanodomains in the PDC microstructure. These nanodomains are a few nanometers in length and allow for the ceramic material to remain amorphous at high temperatures (1000 – 1800 °C) with no crystallization. Various PMCs, on the other hand, remain stable at up to 300 °C of heat and undergo thermal oxidation at temperatures just above this. CMCs have also shown higher oxidation resistance, due to the formation of an oxide layer on the ceramic interface. In the case of PDCs, the oxidation resistance increases with the amount of free Carbon in the nanostructure, which is parabolically related. In this context, Si-based precursor-derived ceramics (PDCs) have processing flexibility that allows to achieve desired shape and control of the final ceramic product. PDCs have shown high resistance to various loads, deformation, and creep. In this study, SiCN/CF, and Si(B)CN/CF CMC mini-composites were fabricated with carbon fiber (CF) reinforcement using Polysilazane-based single-source liquid precursors. The samples used for mechanical testing were fabricated using individual bundles of non-woven carbon fibers, containing approximately 6000 fibers per sample. All fibers were positioned in the same direction and each sample was cut to 4 cm in length. Samples used for oxidation testing on the other hand, were circular in shape and woven in a perpendicular, 90° fiber orientation. A polysilazane-based precursor was mixed with boron-containing precursors to synthesize Si(B)CN polymeric precursor.  The homogenous solutions of the precursors were then allowed to infiltrate the CFs via a drop-coating process. The coated CFs were cross-linked at 180 °C for 16 h and later pyrolyzed at 800 °C for 30 min in an argon atmosphere to achieve CMC mini-composites. The SiCN/CF and Si(B)CN/CF composite bundles exhibited high mechanical strength at room temperature, averaging a max. stress of 390 and 110 MPa respectively under tensile load. These values further prove the higher mechanical strength of CMCs over PMCs, which have a much lower max. tensile stress in most cases. The CMC mini-composites also showed improved oxidation resistance of up to 1500 °C, when compared to base CF material, as the bare carbon fibers were shown to be unstable at just 800 °C.  

Presenting Author: Mohammed Rasheed Kansas State University

Presenting Author Biography: Mohammed Rasheed is a current Undergraduate Senior in the Mechanical and Nuclear Engineering department at Kansas State University. He is an aspiring researcher with an interest in Nanomaterials and Mechanics in the micro scale.

Authors:

Mohammed Rasheed Kansas State University
Shakir Bin Mujib Kansas State University
Gurpreet Singh Kansas State University