Controlled Synthesis, Processing, and Applications of Structural and Functional Nanomaterials: Nanoparticles & Nanocomposites II
Sponsored by: ACerS Basic Science Division, ACerS Electronics Division, ACerS Engineering Ceramics Division
Program Organizers: Haitao Zhang, University of North Carolina at Charlotte; Gurpreet Singh, Kansas State University; Kathy Lu, University of Alabama Birmingham; Edward Gorzkowski, Naval Research Laboratory; Jian Shi, Rensselear Polytechnich University; Michael Naguib, Tulane University; Sanjay Mathur, University of Cologne

Wednesday 2:00 PM
October 20, 2021
Room: B240/241
Location: Greater Columbus Convention Center

Session Chair: Kathy Lu, Virginia Tech; Edward Gorzkowski, Naval Research Laboratory

2:00 PM
Bulk Nanostructured Ceramics Research at the US Naval Research Lab: Edward Gorzkowski¹; James Wollmershauser¹; Eric Patterson¹; Heonjune Ryou¹; Kevin Anderson¹; Boris Feigelson¹; ¹Naval Research Laboratory
    At the US Naval Research Lab (NRL) we have been utilizing and developing several processing routes in order to create and tailor unique microstructures in metals and ceramics. These techniques include 2 stage sintering, aerosol deposition, high-pressure processing, microwave sintering, and electrically assisted sintering. The goal of most of these techniques is to create fully dense bulk nanostructured ceramics. The impetus for this is the many theoretical and experimental studies showing tremendous enhancements in functional properties of nanostructured materials. Nanostructure features can bring dramatic improvements to a wide range of properties including magnetic exchange coupling, thermoelectric energy conversion, and mechanical response. However, these improvements are generally only expected when porosity is negligible and the microstructural length scales are well below 50nm, which is a technological challenge, especially in nanocrystalline ceramics processing. This talk will highlight our new work and demonstrate promising processing techniques for next generation materials.

2:20 PM  Invited
Polymer Derived Ceramics and Composites- From Nanoscale to Bulk Properties: Lisa Rueschhoff¹; Zlatomir Apostolov¹; Matthew Dickerson¹; Michael Cinibulk¹; ¹Air Force Research Laboratory
    Historically, both inherent processing difficulties and catastrophic brittle failure in ceramics have limited their use in high stress, critical applications. Preceramic polymers offer functionality beyond conventional powder processing techniques to enable new and enhanced processing and performance for ceramics. In this presentation, critical aspects and features in the structure-properties-processing of polymer derived ceramics across all length scales will be covered. Starting at the nanoscale, manipulation of ceramic nanostructure has led to the discovery of new properties and behaviors that are distinct from the bulk scale. For example, ceramic mechanical metamaterials have been designed that exhibit ductile-like deformation and strain recovery due to their tailored nanostructure design. On the maco and bulk scale, preceramic polymer thermal evolution through cross-linking and pyrolysis leads to defect formation. Here, these defects will be discussed as they relate to different processing techniques such as additive manufacturing direct ink writing and polymer infiltration and pyrolysis.

2:50 PM  Invited
Polymer-Derived Ceramic Nanocomposites for Applications at High Temperatures and in Harsh Environments: Emanuel Ionescu¹; ¹TU Darmstadt
    Polymer-derived ceramic nanocomposites (PDC-NCs) can be synthesized via thermal conversion of suitable single-source precursors, leading in a first step to amorphous single-phase ceramics, which subsequently undergo phase separation processes to furnish bi- or multiphase ceramic nanocomposites. PDC-NCs have been shown to be excellent candidate materials suitable for applications at (ultra)high-temperatures and under harsh environments. In the present work, amorphous SiMC-, SiMCN- and SiMBCN-based materials (M = Ti, Hf, Ta) were synthesized via cross-linking and ceramization of tailor-made single-source precursors. High-temperature annealing of the obtained amorphous ceramics led to PDC-NCs with promising compositions, such as SiC/MC, MN/Si3N4/SiBCN or MC/MB2/SiC. The presented results emphasize a convenient preparative approach to nano-structured (ultra)high-temperature stable materials starting from greatly compliant single-source precursors. Recent results concerning the stability of the prepared ceramic nanocomposites in ultraharsh environments (i.e., oxidative atmosphere, combustion atmosphere, hydrothermal environment) will be highlighted and discussed.

3:20 PM
Sintering, Structure, and Properties of Y₂O₃-ZrO₂-Al₂O₃ Core-Shell Nanocomposite Ceramics: Kevin Anderson¹; Benjamin Greenberg¹; Mason Wolak¹; James Wollmershauser¹; Boris Feigelson¹; ¹U.S. Naval Research Laboratory
    Composite materials embody the pursuit of synergy in materials, an effort to retain the desirable properties of constituents while compensating for their shortcomings. To this end, core-shell based structures represent highly uniform and intimate composites which could be tailored through core and shell customization. Additionally, nanoscale core-shell based composites could exploit size-dependent effects such as the Hall-Petch effect for additional property enhancements. Using Y₂O₃-ZrO₂-Al₂O₃ as a model system, the effects of grain size and shell thickness on core/shell integrity and mechanical properties were investigated. Core-shell powders were produced through particle atomic layer deposition (pALD), then sintered using the Environmentally Controlled – Pressure Assisted Sintering (EC-PAS) approach. EC-PAS utilizes the creation and preservation of pristine nanoparticle surfaces throughout the sintering process, applied pressure (<2 GPa), and low temperature (< 0.5 T_m) to achieve densification with negligible grain growth. Core-shell powders and nanocomposites were characterized with XRD, SEM, and Vickers microindentation.