Preceramic Polymers; Synthesis, Processing, Modeling, and Derived Ceramics: On-Demand Oral Session: Preceramic Polymers
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
Friday 8:00 AM
October 22, 2021
Room: On-Demand Room 4
Location: MS&T On Demand
Session Chair: Matthew Dickerson, Air Force Research Laboratory
Invited
Novel Hydrogen Chemisorption Properties of Polymer-derived Amorphous SiAlN Compounds: Yuji Iwamoto1; 1Nagoya Institute of Technology
An amorphous compound consisting of p-block elements, namely Si, Al and N elements was synthesized by pyrolysis of an Al-modified polysilazane at 1273 K under flowing ammonia. H2-TPD measurements revealed that the unique reversible H2 adsorption and desorption properties of the polymer-derived amorphous SiAlN. The measured activation energy for H2-desorption was approximately 44 kJ/mol, which was sufficiently high to be assigned as H2 chemisorption. The reversible H2 chemisorption and desorption was successfully identified by 27Al MAS NMR spectroscopic analyses: the results strongly suggested that the local structural reorientation reversibly occurs between undetectable highly distorted Al sites and clearly detectable five-coordinate Al sites by H2 adsorption and desorption. Further study on CO2 hydrogenation on the amorphous SiAlN will be shown and the results will be discussed aiming to develop transition or noble metal-free advanced materials for clean energy applications such as advanced hydrogen production, storage and transportation systems.
Invited
Synthesis and 3D Printing of Antibacterial Polymer-derived Bioceramic Scaffolds for Bone Engineering Applications: Joelle El Hayek1; Laurence Soussan1; Philippe Miele1; Mikhael Bechelany1; Chrystelle Salameh1; 1Institut Européen des Membranes
Bioceramics, widely used for bone engineering due to their biocompatibility and tunable properties, generally display poor antibacterial activity. Infection at the site of implantation can cause failure in bone healing process; therefore, developing antibacterial bioceramics with good mechanical and microstructural properties is required. In this work, customized 3D β-Ca2SiO4 structures were fabricated by combining the PDCs route and Stereolithography-3D printing. β-Ca2SiO4 scaffolds have been successfully manufactured starting from commercial silicone polymer and inorganic oxide fillers mixed with a biobased photosensitive resin and a “home-made” photosensitive preceramic polymer. After pyrolysis, the scaffolds were functionalized by silver nanoparticles uniformly dispersed on graphene oxide. XPS and TEM analysis along with EELS confirmed the formation of silver nanoparticles throughout the graphene oxide with average particle diameter of 30nm. The antibacterial activity was demonstrated on Escherichia coli. Due to their interconnected porosity, mechanical and antibacterial properties, these cytocompatible scaffolds appear suitable for bone engineering.
Invited
Polymer-derived UHTC Synthesis: Matthew Laskoski1; 1US Naval Research Lab
Ultra-high temperature ceramics (UHTCs) demonstrate significant promise in armor and hypersonic engine applications. However, existing materials are too brittle and expensive to incorporate into aerospace and military systems. Our approach produces dense, nanostructured, monolithic UHTC composites with various inclusions that maximize density, hardness, and durability under high temperatures. We developed a novel synthesis route that yields shaped carbides, nitrides, and borides from compressed powder mixtures of metal precursors and high char-yielding resins. We incorporate metals, fibers, and ceramics into these composites to improve their mechanical, electrical, and thermal properties and adapt them for many vital applications.
Superparamagnetic Silicon Carbonitride Ceramic Fibers through In-situ Generation of Iron Silicide Nanoparticles: Guenter Motz1; Antoine Viard1; Birgit Weber1; Samuel Bernard2; 1University of Bayreuth; 2CNRS IRCER Limoges
Non-oxide ceramic fibers are sophisticated, key structural components with superior mechanical and thermal properties. Most of the applications are safety-relevant components, whose damage is difficult to detect. Furthermore, it would benefit to include functional properties in addition to structural aspects. Hence, we developed novel functional superparamagnetic, iron-containing SiCN ceramic fibers derived from an iron-modified, meltable polysilazane via melt-spinning, curing and pyrolysis at 1000 °C. Tensile strength values of 1.24 GPa were measured for fibers with diameters up to 40 µm. Despite a slightly reduced oxidation stability, these ceramic fibers are suitable for structural applications. Transmission electron microscopy confirms the formation of nano-crystalline FeSi, Fe3Si, and Fe particles with a size up to 7.5 nm. Due to the well distributed iron-containing nanoparticles, the ceramic fibers exhibit superparamagnetic behavior for temperatures higher than 26 K with a saturation magnetization of 1.54 emu∙g-1 at 300 K.
Thermomechanical Performance of a Novel Class of Ultra-high Temperature Polymer Derived La Containing Zr-B-C-(O) Ceramics: Gokul Gopakumar1; Ganesh T1; Renjith Devasia2; Ravi Kumar1; 1Indian Institute of Technology Madras; 2Vikram Sarabhai Space Centre
Due to the poor oxidation resistance of silicon-based polymer-derived ceramics (PDCs) at temperatures above 1600 °C, a new PDC was synthesized to obtain ultra-high temperature ceramics with better oxidation resistance. In this work, La incorporated Zr-B-C-(O) ceramics were synthesized by modifying phenol formaldehyde resin with precursors of lanthanum, zirconium and boron. The resulting polymer and its bonding characteristics were studied using FTIR and its pyrolysis temperature was determined using TGA. From X-ray diffractograms, the as-pyrolysed ceramics were found to be amorphous. On heat treatment at 1600 °C, the ceramic crystallised into La2Zr2O7, tetragonal-ZrO2, and ZrC. However, by increasing the amount of boron added during precursor synthesis, the crystallization of the above phases was suppressed and the amorphous state of the material was stabilised. The microstructural analysis of the phases was done using TEM. Thermomechanical properties like density, dilatometry, hardness, moduli, and oxidation resistance was measured on the spark-plasma-sintered ceramic.
Laser and Furnace Pyrolyzed Organosilazane-based Glass/ZrO2 Composite Coating Systems: A Comparison: Alexander Horcher1; Katja Tangermann-Gerk2; Walter Krenkel1; Günter Motz1; 1University of Bayreuth; 2Bayerisches Laserzentrum Erlangen
Protective ceramic-based coatings are frequently the most suitable and cost-effective solutions for problems like corrosion, oxidation and wear. It has been shown, that the precursor technology is suitable for the preparation of ceramic coatings by pyrolysis in a furnace. However, the required high temperatures for the preparation of the ceramic coatings only allow the use of temperature-resistant substrates. A very innovative approach to overcome this restriction is the use of laser radiation as an energy source for the pyrolysis of the preceramic polymer. For this reason, a composite coating system composed of an organosilazane with ZrO2 and glass particles as fillers was developed suitable for pyrolysis with a Nd:YAG laser. The composite coating slurry was applied onto stainless steel substrates by spraying and afterwards irradiated with a Nd:YAG laser. Finally, the microstructure, chemical composition, abrasions resistance as well as the mechanical and corrosion behavior was investigated.
Additive Manufacturing of Hybrid Polymer-derived Ceramics via Core-shell Direct-ink Writing: Robert Pack1; James Kemp1; Brett Compton1; 1University of Tennessee Knoxville
A significant amount of work in recent years has focused on the use of preceramic polymer feedstocks filled with structural and/or functional fillers such as carbides, nitrides, and other carbon fillers. Such work provides a foundation and opportunity for new material formulation and additive manufacturing (AM) process development that we aim to build upon. In this work, we utilize the AM process of direct-ink writing, coupled with implementation of a novel co-extrusion, core-shell printhead, to fabricate hybrid polymer-derived ceramic composites with a core-shell motif to achieve unique structural and functional properties. Specifically, this talk will focus on the creation and characterization of electrically conductive and insulating polysilazane-derived materials to enable AM of high temperature sensors and related applications. Rheological characterization, printing behavior, and post-pyrolysis properties will be highlighted, and challenges with co-processing in the core-shell motif will be discussed.
Metal-coordinated Preceramic Polymer Hairy Nanoparticles for Ultra-high Temperature Structural Materials: Maria Parvulescu1; Kara Martin2; Christina Thompson2; Matthew Dickerson2; 1Air Force Research Laboratory; 2AFRL
Ceramics matrix composites (CMCs) and ultra-high temperature ceramics (UHTCs) are vital structural materials for hotter, more efficient engines and turbines. Their use is hampered by many issues including how to make novel, more processable materials. Preceramic polymers (PCPs) are used in an infiltration-pyrolysis process to make CMCs. Limitations include the number of cycles required due to volume shrinkage and cracking, and the small number of UHTC-producing PCPs. Preceramic polymer hairy nanoparticles (PCP HNPs) composed of an inorganic core and organic corona reduce the number of cycles and have improved rheology. Our first generation PCP-HNPs had the core and corona covalently attached, and our second-generation explores attachment via metal-coordination. The structure and rheological properties and the inclusion of metals gives tailorable materials for structural applications, and expands their use for UHTCs. Synthesis and characterization of PCP HNPs and their ceramic progeny will be discussed and compared to our first-generation PCP-HNPs.
SiOC Coatings on Yttria Stabilized Zirconia Microspheres Using a Fluidized Bed Coating Process: Sanjay Kumar1; Kathy Lu1; 1Virginia Polytechnic Institute and State University
Defect-free SiOC coatings of 50-100 µm thickness were prepared on YSZ microspheres by a fluidized bed coating process. Effects of rheological properties of the coating solution on the coating process were elucidated. An impact regime diagram was constructed, which demonstrated that the coating mechanisms were collision/impact. During the fluidized bed coating, longer spouted time resulted in wider dispersion, longer residence time, and more circulatory motion of particles; fluid distributed more uniformly throughout the column, as demonstrated in our MFiX simulations. Two-step pyrolysis in Ar achieved complete coating layers, which were comprised of SiOC, SiO2 , SiC, and graphite. The two-stage mass loss during the pyrolysis corresponded to simultaneous reactions due to depolymerization and hydrocarbon loss from 400-6000C. Carbon cluster size in the pyrolyzed samples was calculated to be 25±2Å. This work provides a new method for producing SiOC coatings on micron spheres, with nuclear TRISO fuel particles as the application.
Preceramic Polymer Organization via Block Copolymer Templating: John Bowen1; Lisa Rueschhoff2; Shahryar Mooraj3; Jacob Goodman4; Emily Davidson5; Benito Roman-Manso5; K. L. Martin1; Scott Schiffres4; Wen Chen3; Matthew Dickerson2; Jennifer Lewis5; 1UES Inc.; 2Air Force Research Lab; 3University of Massachusetts Amherst; 4Binghamton University; 5Harvard University
Preceramic polymers offer wide flexibility in terms of processing and organization, particularly in terms of their use for nanoscale ceramic fabrication. Nanoscale ceramics are of interest due to ceramics’ intrinsic high hardness and temperature resistance in combination with nanoscale advantages such as high surface area and reduced part densities. These materials hold promise in a number of areas, whether for light-weighting parts, catalysis/separation substrates, or mechanical metamaterials. We use block copolymers to template preceramic polymers for the fabrication of bulk ceramic parts with nanoscale features. By tuning the ratio of block copolymer to preceramic polymer, we are able to access a number of morphologies and resulting ceramic porosities. These materials are also useful in direct ink writing applications and can be applied to create macroscale parts (mm-m) of arbitrary geometries with nanoscale features. These materials may be useful for energy absorption applications, among others.
Isoconversional Methods and Kinetic Reaction Models for Cure Modelling of Commercial Pre-ceramic Polymers and their Blends: Zlatomir Apostolov1; Elizabeth Heckman2; Michael Cinibulk1; 1Air Force Research Laboratory; 2Wright State University
Cure activation energies for three commercially available pre-ceramic polymers and their blends were determined through conventional and isoconversional approaches, utilizing the Ozawa, Kissinger, and Friedman methods. Three reaction models were evaluated for modelling the cure kinetics of the investigated systems, and the results of the two most successful (nth Order and Prout-Tompkins autocatalytic) are presented. The activation energies determined from the modelling effort were then compared to those obtained from the dedicated conventional and isoconversional studies. Additionally, the dependence of conversion rates on heating rate and conversion fraction was compared for each polymer and blend, and the resulting trends are presented.
Impact of Preceramic Polymer Architecture on Derived Ceramics
: Timothy Pruyn1; Matthew Dickerson1; Brandon Ackley1; 1Materials and Manufacturing Directorate
While strides have been made in understanding processing factors which contribute to ceramic yield and composition made through preceramic polymers, comparatively little is known regarding the impact of minor changes to the polymer backbone. Herein, we examine the impact of chemical connectivity (i.e. the arrangements of elements in polymers with the same empirical chemical formula) on ceramic yield and composition through new preceramic polymers using CuAAC. Zirconium and silicon containing polymers with varied connectivity are investigated, with differences in ceramic yield as large as 10% identified. Additionally, ceramic composition is seen to vary depending on connectivity during and after pyrolysis.
Evolutive State and Damage Modeling and Characterization for PIP-based Hypersonic Vehicle Materials: Rick Hall1; Zlatomir Apostolov1; Ashley Hilmas1; George Jefferson1; Vikas Varshney1; Michael Cinibulk1; Robert Brockman2; Rebecca Hoffman2; Thomas Key3; Derek King3; 1Air Force Research Laboratory; 2University of Dayton Research Institute; 3UES
While it allows for scale, relative expediency, and extreme durability, the unpredictable nature of microstructural evolution during PIP processing in the form of cracks, pores, and strain rates leads to significant variability in final CMC properties and shape. This is currently the most significant obstacle towards broader CMC utilization. The proposed work will develop material models driven by detailed experimental observations to better understand the variability in microstructural evolution during PIP processing, and the consequent effects on the composite’s ability to function as intended in hypersonic environments. The modeling aspect of this work will feature the precursor chemomechanical evolution during infiltration, cure, and pyrolysis of C/SiC, along with C/SiC oxidation behavior under representative in-service environments. A continuum/discrete damage and porosity simulation framework is being developed, which is capable of rendering the coupling between pyrolytic, oxidative, large volumetric, thermal and viscous responses of the constituent materials during multiple PIP processing cycles.
Embedded Direct Ink Writing of Freeform Ceramic Components: Kai Huang1; Hamada Elsayed1; Giorgia Franchin1; Paolo Colombo1; 1University of Padova
Direct ink writing, a widely used additive manufacturing technique, has some disadvantages in fabricating suspended ceramic structures due to instabilities in the ink caused by gravity forces, requiring a strict optimization of the rheology of the feedstock. To overcome this problem, freeform 3D printing was achieved in this work by performing printing inside a supporting medium. The rheological properties of the supporting medium as well as the printability of the ink as a function of the solid content were investigated. Printing parameters such as gas pressure and nozzle movement speed were optimized. Several suspended structures were fabricated, such as coils and hollow cylinders, showing no shape distorting both after printing and pyrolysis. Besides preceramic polymer, we also demonstrated that with this approach it is possible to print using inks containing either metal or ceramic powders, thereby showcasing the large potential of this approach for being used in different applications.
Study on Manufacturing of Silsesquiazane Derived Hierarchically Porous Silicon Carbonitride Ceramics with Aligned Macropore by Freeze-casting Method: Tae-Hwan Huh1; Young-Je Kwark1; 1Soongsil University
Hierarchically porous ceramics have superior properties in comparison with conventional porous ceramic. Micro-/mesopores, which have size of smaller than 50 nm, give the large surface area and selectivity to the component, while macropores of larger than 50 nm give large pore volume and improve heat/mass transfer properties. Especially, ceramics with aligned macropore can be used in many applications such as filter, adsorbent, and catalyst because the pores give high flux of liquid or gaseous media. Freeze-casting is one of the best methods to fabricate the aligned macropores. In this study, we manufactured hierarchically silicon carbonitride (SiCN) ceramics with aligned macorpores using silsesquiazane (SSQZ) as a SiCN precursor. SSQZ could be obtained in solid form due to its branched structure, and resulted in improving structural stability without additional crosslinking process. In addition, we used organic polymers as a binder to further improve the stability.