Document Type

Thesis

Degree

Master of Science (MS)

Major/Program

Materials Science and Engineering

First Advisor's Name

Arvind Agarwal

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Norman Munroe

Third Advisor's Name

William Kinzy Jones

Keywords

Tantalum Carbide, graphene, graphene nanoplatelets, spark plasma sintering, nanocomposites, ceramic matrix composites, ultra high temperature ceramics, high temperature oxidation, fracture toughness

Date of Defense

3-25-2013

Abstract

Hypersonic aerospace vehicles are severely limited by the lack of adequate high temperature materials that can withstand the harsh hypersonic environment. Tantalum carbide (TaC), with a melting point of 3880°C, is an ultrahigh temperature ceramic (UHTC) with potential applications such as scramjet engines, leading edges, and zero erosion nozzles. However, consolidation of TaC to a dense structure and its low fracture toughness are major challenges that make it currently unviable for hypersonic applications. In this study, Graphene NanoPlatelets (GNP) reinforced TaC composites are synthesized by spark plasma sintering (SPS) at extreme conditions of 1850˚C and 80-100 MPa. The addition of GNP improves densification and enhances fracture toughness of TaC by up to ~100% through mechanisms such as GNP bending, sliding, pull-out, grain wrapping, crack bridging, and crack deflection. Also, TaC-GNP composites display improved oxidation behavior over TaC when exposed to a high temperature plasma flow exceeding 2500 ˚C.

Identifier

FI13042212

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