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 Co-Chair

Second Advisor's Name

Benjamin Boesl

Second Advisor's Committee Title

Committee Co-Chair

Third Advisor's Name

Zhe Cheng

Third Advisor's Committee Title

Committee Member

Keywords

Boron Nitride Nanotubes, interfacial reactions, Titanium composite, spark plasma sintering, dispersion of BNNT

Date of Defense

6-21-2019

Abstract

In this study, Boron Nitride Nanotube (BNNT) reinforced Titanium matrix composites are synthesized by Spark Plasma Sintering. Two main challenges directly affecting the mechanical performance of BNNT-metal matrix composites are addressed:(i) Homogenous dispersion of high surface energy BNNTs, and (ii) Controlling interfacial reactions at the metal/nanotube interface. High-energy ultrasonication induced dispersion resulted in the functionalization of BNNTs by -OH radicals proving its suitability over surfactant assisted dispersion routes. The sintering of Ti (99% relative density) was achieved at 50% less processing temperature than those used in conventional sintering to minimize interfacial reactions when reinforced with BNNTs. The reduction of temperatures in addition to the reduction (by 91%) in processing times was shown to control reaction phases. Bulk compressive yield strengths of Ti-BNNT sintered at low (750oC) and high (950oC) temperatures were improved by 21% and 50% respectively, as compared to Ti alloy without reinforcement. Twin boundaries, pinning of dislocations by BNNTs, and crack bridging were strengthening mechanisms identified in the composites.

Identifier

FIDC007792

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