Preceramic Polymers; Synthesis, Processing, Modeling, and Derived Ceramics: Preceramic Polymers and Polymer Derived Ceramics I
Sponsored by: ACerS Engineering Ceramics Division
Program Organizers: Matthew Dickerson, Air Force Research Laboratory; Gurpreet Singh, Kansas State University; Paolo Colombo, University of Padova; Günter Motz, Universität Bayreuth
Wednesday 8:00 AM
October 20, 2021
Room: B230
Location: Greater Columbus Convention Center
Session Chair: Matthew Dickerson, Air Force Research Laboratory
8:00 AM Introductory Comments Organizers' Remarks
8:10 AM Invited
UV Curable Preceramic Polymers and their Application in Additive Manufacturing: Tobias Schaedler1; Kayleigh Porter1; Mark O'Masta1; Ekaterina Stonkevitch1; Zak Eckel1; Phuong Bui1; 1HRL Laboratories LLC
This talk explores the development of UV curable preceramic polymers for use with liquid-vat type 3D printing, such as stereolithography or digital light processing. We demonstrate that additions of UV functional groups to siloxanes and carbosilanes allow for additive manufacturing on commercial printers, after optimizing resin and printing parameters. We additionally show integration of fibers or particles within the resin will carry through pyrolysis into the final ceramic state. This creates a ceramic matrix composites from the resulting two-phase microstructure, offering several advantages over conventional ceramic printing feedstock based on organic acrylates with a high volume fraction of ceramic particles. The talk will further discuss how many of the same benefits and challenges present in traditional thermally-cured preceramic polymers are still present when additively manufactured and how the new manufacturing paradigm enables new ways to address the challenges and enables access to new applications from the increased design freedom.
8:40 AM
Preparation of ZrC-embedded Glass-like Carbon Wires via Thermal Decomposition of Metal Organic Frameworks: Kaitlyn Shirey1; Brittany Bonnett2; Xiaozhou Yang2; Amanda Morris2; Carolina Tallon2; 1Virginia Polytechnic Institute; 2Virginia Tech
Metal organic frameworks (MOFs) are crystalline coordination polymers composed of multidentate organic linkers bridging metal nodes to form porous structures. The carbonization of MOFs has several advantages for synthesis of materials, from simple preparation to great freedom for modification. In this study, we show an alternate route to the synthesis of zirconium carbide (ZrC) within a highly anisotropic particle through heat treatment at 2000°C of MOF PCN-222. Resulting particles show the same needle-like morphology as MOF particles, but now consist of a glass-like carbon skeleton with embedded ZrC crystals. The new morphology is visible in electron microscope images. Thermogravimetric analysis was used to confirm the MOF decomposition, and through diffraction and spectroscopy methods, the particles are determined to be ZrC crystals within a glass-like carbon matrix. These wire-like particles have potential as reinforcements for high temperature applications and as a synthetic route for ultra-high temperature ceramics with unique morphologies.
9:00 AM
X-ray Computed Tomography Investigation of CMC Densification via Polymer Infiltration and Pyrolysis: Derek King1; Thomas Key1; Connor Wycoff1; Craig Przybyla2; Michael Cinibulk2; 1UES Inc; 2AFRL
X-ray computed tomography (XCT) was utilized to analyze a plain weave, carbon fiber, ceramic matrix composite (CMC) and assess its densification via the polymer infiltration and pyrolysis (PIP) process. The relative nesting and stacking of tows in the X and Y directions, for adjacent plies, produced three ply relationships, defined as Type I, Type II, and Type III. These ply relationships were correlated to the formation of large void spaces within the composite. Such void spaces have been previously observed to remain, even after PIP densification. XCT analysis after each PIP cycle revealed that fine void features, such as cracks or delaminations, were filled and began to densify from the first PIP cycle; however, the large void structure remained unfilled. In this talk, the formation of the large void structure will be discussed and the possible mechanisms that prohibit or facilitate CMC densification, via PIP processing, will be introduced.