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<b><span style="font-size:20.0pt; font-family:"Tahoma","sans-serif"">The Materials Science and Engineering Program</span></b></p>
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<b><span style="font-size:16.0pt; font-family:"Tahoma","sans-serif""> </span></b></p>
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<b><span style="font-size:16.0pt; font-family:"Tahoma","sans-serif"">Invites the Cullen College of Engineering
</span></b></p>
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<b><span style="font-size:16.0pt; font-family:"Tahoma","sans-serif"">To the </span>
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<b><span style="font-size:16.0pt; font-family:"Tahoma","sans-serif"">PhD Dissertation Defense</span></b></p>
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<b><span style="font-family:"Tahoma","sans-serif""> </span></b></p>
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<b><span style="font-size:12.0pt; line-height:200%; font-family:"Tahoma","sans-serif"">TRIBOLOGY OF PTFE/PEEK COMPOSITE AT ELEVATED TEMPERATURE</span></b></p>
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<b><span style="font-size:14.0pt; font-family:"Tahoma","sans-serif"">Shuren Qu</span></b></p>
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<b><span style="color:#1F497D"> </span></b></p>
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<b><span style="font-size:12.0pt">Date: Wednesday, July 31<sup>st</sup>, 2019</span></b></p>
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<b><span style="font-size:12.0pt"> </span></b></p>
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<b><span style="font-size:12.0pt">Location: </span></b><span style="font-size:12.0pt">Technology Bridge</span><span style="font-size:12.0pt"> Building 3 Room 125<b></b></span></p>
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<b><span style="font-size:12.0pt">Time: </span></b><span style="font-size:12.0pt">2:30 pm – 5:00 pm<b></b></span></p>
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<b><span style="font-size:12.0pt"> </span></b></p>
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<b><span style="font-size:12.0pt">Committee Chair:<span style="color:#1F497D"> </span>
</span></b><span style="font-size:12.0pt"> Prof. Su Su Wang<b><span style="color:#1F497D"></span></b></span></p>
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<b><span style="font-size:12.0pt"> </span></b></p>
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<b><span style="font-size:12.0pt">Committee Members:</span></b></p>
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<span style="font-size:12.0pt">Prof. Alamgir Karim</span></p>
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<span style="font-size:12.0pt">Prof. Megan Robertson</span></p>
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<span style="font-size:12.0pt">Prof. Akira Miyase</span></p>
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<span style="font-size:12.0pt">Prof. King Him Lo</span></p>
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<span style="font-size:12.0pt"> </span></p>
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<span style="">Engineering thermoplastics are used extensively in reciprocating and rotating machinery. For example, Polyetheretherketone (PEEK) and its composites are commonly used as sealing materials in compressors and pumps. Neat PEEK polymer is known for
its outstanding chemical resistance, thermal stability, and high-temperature mechanical strength. Despite these attractive properties, a critical concern of the PEEK polymer in tribological applications is its high friction, which could lead to serious problems,
such as high local flash temperature and severe wear. A common practice to reduce the high friction is to incorporate solid-state lubricants, such as polytetrafluoroethylene (PTFE), into the polymer. In view of the wide use of PTFE/PEEK composite for tribological
applications, predictive models and theories are needed to better understand friction and wear mechanisms of the composite and accelerate development and applications of the composite for tribological operations.
</span></p>
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<span style="">In the experimental phase of this study, friction and wear of PTFE/PEEK composites with various PTFE contents were determined at different. Elevated temperature mechanical properties of neat PEEK, PTFE and their composites, such as elastic modulus
and compressive yield stress, were also determined. Quantitative methods for characterization of the transfer films were developed. The area coverage ratio and composition of composite transfer films were investigated with an in-house developed computer software
and XPS, respectively. Important experimental results were obtained and used for subsequent developments of friction and wear models and theories.</span></p>
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<span style="">In the theoretical phase of the study, a power-law relationship between PTFE/PEEK composite friction and wear is first established based on experimental results. Friction and wear models are established for developing theories on PTFE/PEEK composite
sliding friction and wear at low temperature. Solid film lubrication is introduced along with the rule of the mixtures to derive the new friction and wear theories for the polymer composite. For elevated temperature friction and wear of the PTFE/PEEK composite,
mechanism-based friction and wear models are proposed for the development of the new tribological theories to predict the friction and wear of PTFE/PEEK composite. Detailed mechanisms and mechanics of low and elevated temperature friction and wear of the PTFE/PEEK
composites are discussed.</span></p>
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<span style="">__________________________________________________________________________________________________________________________________________________________</span></p>
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