PhD Dissertation: GİZEM DEMİR TUNÇBAŞ,TOWARD CIRCULAR AND NEAR-NET-SHAPE MANUFACTURING OF ADVANCED CERAMICS: A DOUGH-BASED APPROACH FOR GREEN MACHINING, RECYCLING, AND LASER PROCESSING, Date & Time: July 01, 2026 – 11:00 AM, Place: FENS G035

TOWARD CIRCULAR AND NEAR-NET-SHAPE MANUFACTURING OF ADVANCED CERAMICS: A DOUGH-BASED APPROACH FOR GREEN MACHINING, RECYCLING, AND LASER PROCESSING

GİZEM DEMİR TUNÇBAŞ
Materials Science and Nano Engineering, PhD Dissertation, 2026 

Thesis Jury

     Prof. Özge Akbulut (Thesis Advisor)

  Prof. Yusuf Ziya Menceloğlu

  Prof. Fevzi Çakmak Cebeci

Prof. Cem Bülent Üstündağ

Prof. Ozan Akdoğan

Date & Time: July 1st, 2026 – 11:00 AM

Place: FENS G035

Keywords : advanced ceramics, recycling, green machining, sustainable processing, circular manufacturing

Abstract

This thesis demonstrates that a simple, water-based dough processing route can enable green-state machining and multi-generational recycling of advanced oxide ceramics, with a particular focus on YSZ and MgO. Advanced ceramics offer exceptional mechanical and chemical performance, yet their broader adoption is limited by the difficulty, cost, and energy intensity of shaping fully sintered, brittle components and by the lack of practical recycling strategies. To address these challenges, the work first formulates a dough-like YSZ system in which a single anionic AMPS-AA copolymer induces polymer-bridging between nanoparticles, yielding malleable, self-standing green bodies at high solids loading that can be shaped, drilled, turned, and laser-machined with predictable shrinkage and high final density.

The same formulation is then extended into a circular manufacturing strategy, showing that green machining scrap and defective parts can be crushed, rehydrated, and reprocessed into fresh doughs across three recycling generations without significant loss in densification, flexural strength, or microstructural quality. Building on this platform, the thesis investigates how CO₂ and Nd:YAG laser processes can be combined with dough-based green bodies to achieve cost- and energy-efficient near-net shaping and functional surface texturing. Green MgO doughs are machined with a benchtop CO₂ laser to identify power–feed rate windows that generate crack-free cuts, through-holes, and complex 3D architectures at minimized energy consumption. Green YSZ doughs are textured using a nanosecond Nd:YAG laser to fabricate periodic groove patterns that survive sintering and enhance osteoblast-like cell viability relative to flat zirconia surfaces, highlighting the potential of dough-based, laser-machined ceramics for both sustainable manufacturing and biofunctional applications.