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Achieving a viable process for advanced manufacturing of ceramics and metal-ceramic composites is a sought-after goal in a wide range of fields including electronics and sensors for harsh environments, microelectromechanical devices, energy storage materials, and structural materials, among others. In this dissertation, the processing, and manufacturing of ceramics and ceramic composites are addressed, specifically, a process for three-dimensional (3D) printing of polymer-derived ceramics (PDC), and a process for low-cost manufacturing as well as healing of metal-ceramic composites is demonstrated.Three-dimensional printing of ceramics is enabled by dispensing the preceramic polymer at the tip of a moving nozzle into a gel that can reversibly switch between fluid and solid states, and subsequently thermally cross-linking the entire printed part “at once” while still inside the same gel was demonstrated. The solid gel converts to fluid at the tip of the moving nozzle, allowing the polymer solution to be dispensed and quickly returns to a solid state to maintain the geometry of the printed polymer both during printing and the subsequent high-temperature (160 °C) cross-linking. After retrieving the cross-linked part from the gel, the green body is converted to ceramic by high-temperature pyrolysis. This scalable process opens new opportunities for low-cost and high-speed production of complex three-dimensional ceramic parts and will be widely used for high-temperature and corrosive environment applications, including electronics and sensors, microelectromechanical systems, energy, and structural applications.
Metal-ceramic composites are technologically significant as structural and functional materials and are among the most expensive materials to manufacture and repair. Hence, technologies for self-healing metal-ceramic composites are important. Here, a concept to fabricate and heal co-continuous metal-ceramic composites at room temperature were demonstrated. The composites were fabricated by infiltration of metal (here Copper) into a porous alumina preform (fabricated by freeze-casting) through electroplating; a low-temperature and low-cost process for the fabrication of such composites. Additionally, the same electroplating process was demonstrated for healing damages such as grooves and cracks in the original composite, such that the healed composite recovered its strength by more than 80%. Such technology may be expanded toward fully autonomous self-healing structures.
ContributorsMahmoudi, Mohammadreza (Author) / Minary-Jolandan, Majid (Thesis advisor) / Rajagopalan, Jagannathan (Committee member) / Cramer, Corson (Committee member) / Kang, Wonmo (Committee member) / Bhate, Dhruv (Committee member) / Arizona State University (Publisher)
Created2022
Description
This thesis investigates auxetic structures' specific energy absorption properties, characterized by their negative Poisson's Ratio (NPR). Auxetics, derived from natural materials and engineered designs, are increasingly applied in automotive, aerospace, and defense industries due to their enhanced material properties like indentation resistance and fracture toughness.
The research commenced with a thorough literature review to gather relevant methodologies and insights into auxetic geometries. This was followed by analytical experiments and simulations focused on the re-entrant auxetic pattern, known for its simplicity and effectiveness. The study tested modifications to this pattern, aiming to enhance energy absorption by adjusting parameters like base thickness and adding filets.
Simulations were performed using ANSYS 2023 R2, modeling the materials under plane stress conditions to assess their mechanical responses. Two main variants were examined: the Enhanced Stiffness pattern, which alters thickness, and the Filet Re-entrant pattern, which incorporates fillets to reduce stress concentrations. Results indicated that both modifications improved energy absorption compared to the standard re-entrant design, with Filet patterns showing superior performance due to their efficient stress distribution.
This work extends the understanding of auxetic materials, demonstrating significant potential to improve safety and functionality in engineering applications through advanced material design.
ContributorsSastriawan, Yoga (Author) / Kang, Wonmo (Thesis director) / Safari, Hamid (Committee member) / Mahmoudi, Mohammadreza (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / Dean, W.P. Carey School of Business (Contributor)
Created2024-05