Doctoral Defense - Evelyn Wang

About the Event

The Department of Chemical Engineering and Materials Science

Michigan State University

Ph.D. Dissertation Defense

Friday, May 9^th, 2025 at 1:00 pm

Seminar Room 3540 Engineering Building and Zoom

Contact Department or Advisor for Zoom Information

ABSTRACT

THERMAL STEREOLITHOGRAPHY OF HIGH-PERFORMANCE POLYMER DERIVED CERAMICS

By: Evelyn Wang

Advisor: Michael Hickner

This dissertation aims to develop a novel thermal stereolithography process for shaping polymer-derived ceramics (PDCs). This method solves issues in UV-based additive manufacturing (AM) for ceramic resin 3D printing where high refractive index (RI) fillers lead to low light penetration and resolution. By adopting a thermal NIR laser for the SLA process and using thermal curing, higher loadings of ceramics with higher RI difference between the particles and the resin can be processed. As a result, resin formulations based on SiC, Si, and Si₃N₄ precursors can be processed with SLA printing to yield 3D structured green bodies that can undergo subsequent pyrolysis to ceramics.

In the first part of the research, an acrylate-based resin composition was proposed for SiC-Composite ceramics thermal SLA. This resin composition is based on passive fillers, which do not change throughout the entire process but contribute to the final ceramic yield. The printed structures are debinded and subject to polymer infiltration pyrolysis (PIP), which densifies and strengthens the printed structures. Using a small amount of preceramic polymer in the resin, a percolated structure was formed between particles during debinding to provide additional support for the porous green part. Various 2 D and 2.5 D structures and lattices composed of SiC-Composite ceramics were fabricated through this process, which has improved mechanical properties (flexural strength and toughness) at low pyrolysis temperatures (800 °C).

In the second part of the research, a preceramic polymer (PCPs)-based resin was utilized for AM of highly crystalline SiC-Composite ceramics using reaction bonding. Elemental silicon nanoparticles were blended into the resin composition as active fillers. This printing of silicon particle-containing resin is only achievable with the thermal SLA process, as silicon has an extremely high RI of 5.44, compared to a refractive index of the resin of approximately 1.4-1.6. The addition of active fillers eliminates the residual carbon from PCP pyrolysis at elevated temperatures and improves mechanical properties.

In-situ Raman spectroscopy was used to characterize the polymer-to-ceramic conversion process for PDCs. This analysis allowed for real-time reaction rates to be measured. The high-temperature polymer reaction kinetics were analyzed with the in-situ setup, and the reaction kinetics were clearly illustrated in this research with complementary ex-situ studies. Finally, highly crystalline SiC-Composite ceramics with overhangs are demonstrated with both lab-scale thermal printers and 3DCeram, Sinto industrial printers. Finite element analysis (FEA) for thermal printing was also conducted to optimize the printing process and maximize the printing resolution.

Persons with disabilities have the right to request and receive reasonable accommodation. Please call the Department of Chemical Engineering and Materials Science at 355-5135 at least one day prior to the seminar; requests received after this date will be met when possible.