Date of Graduation

5-2020

Document Type

Thesis

Degree Name

Bachelor of Science in Mechanical Engineering

Degree Level

Undergraduate

Department

Mechanical Engineering

Advisor/Mentor

Wejinya, Uchechukwu C.

Committee Member

Tian, Ryan

Abstract

Because of their unique mechanical properties, shape memory capabilities and biocompatibility, Nickel-titanium alloys are frequently used in the medical industry for a variety of applications including endodontic files. Until now, the performance of industry-standard endodontic files has been characterized by this alloying property and a limited set of macroscale surface structures and features. In this work, High Resolution Transmission Electron Microscopy (HRTEM), Low Resolution Transmission Electron Microscopy (LRTEM), Scanning Electron Microscopy (SEM), and Energy Dispersive X-Ray Spectroscopy (EDX) analyses are conducted at both the surface and sub-surface levels of a wide selection of industry-grade endodontic files currently offered on the market to more fully characterize their respective performance at both the microscale and nanoscale levels. In conducting these analyses, conclusions are made as to which microscale and/or nanoscale material properties positively or negatively affect the performance of the endodontic file on the macroscale. Ultimately, we propose a method of preventing catastrophic failure within the interior cross-sectional area of the endodontic file by predicting when failure will occur using low-cost technologies and long-standing fundamentals of Materials Science. In concurrence with a revolution in industry, we also present a low-cost, low-energy method of rapidly annealing and nitriding titanium. With ammonium hydroxide (NH4OH) as a source of nitrogen during heat treatment, we have produced an industry-grade titanium nitride sample that reduces the high overhead manufacturing costs and energy consumption associated with alternative methods (See salt bath nitriding and plasma nitriding). A Vickers Hardness (Hv) test was conducted to evaluate the material properties of the resulting sample in relation to a control sample of pure titanium. The nitrided sample yielded a 211.4% increase in Hv relative to the control. X-Ray Diffraction (XRD) was used to evaluate the crystal structure of the resulting sample. 8 The XRD scans of the NH4OH-nitrided sample are consistent with that of industry grade titanium nitride. A second novel method of nitridation is also investigated. Using nitrogen gas (N2) during heat treatment, we have produced an industry-grade titanium nitride sample that similarly reduces the high overhead manufacturing costs and energy consumption associated with alternative methods. A Vickers Hardness (Hv) test was similarly conducted to evaluate the material properties of the resulting sample in relation to a control sample of pure titanium. The nitrided sample yielded a 200.67% increase in Hv relative to the same control. X-Ray Diffraction (XRD) was also used to evaluate the crystal structure of the resulting sample. The XRD scans of the nitrided sample are also consistent with that of industry grade titanium nitride. After data collection, a revised Newton-Raphson method of numerical approximation was used to computationally simulate the material hardness and manufacturing cost evaluation for any variable time of heat treatment—for both novel methods of nitridation.

Keywords

HRTEM; LRTEM; XRD; Vickers Hardness; Titanium Nitride; Nitridation

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