Jie Lian - US grants

NON-TECHNICAL DESCRIPTION:
The survival of materials under conditions of high temperature and radiation is crucial to their application in nuclear energy, space, and other applications under extreme conditions. Metal alloys can be strengthened by the dispersion of small (nanoscale) oxide particles. Yttrium titanium oxide nanoparticles greatly enhance the thermo-mechanical and radiation-resistant properties of such oxide-dispersion strengthened (ODS) alloys. It is scientifically challenging but technologically necessary to understand the exceptionally-high stability of these nanoparticles under extreme environments in order to develop advanced structural materials with enhanced performance. By synergy of experimental efforts and multi-scale computer simulations, the researchers at RPI and UC Davis will advance the understanding and control of transformation and structural evolution of such nanoparticles. This research program will train both graduate and undergraduate students working in key fields of radiation effects and the development of advanced structural materials. Special efforts will be made to involve underrepresented students, particularly woman engineers, into science and engineering through various programs at RPI and UC Davis. The fundamental understanding will contribute to the development of a dual-level course of ?radiation effects and nuclear reactor materials? at RPI. Findings of this project will be disseminated to a wider audience through national and international conference presentations.

TECHNICAL DETAILS
Building on a synergy of experiments and atomistic simulations, the groups at RPI and UC Davis will target a scientific understanding of the phase stability of dispersed oxide nanoparticles under high temperature and intense radiation conditions. Y-Ti-O nanoparticles (e.g., Y2Ti2O7 and Y2TiO5) will be synthesized and exposed to different irradiation conditions using intense ion beams and to different temperatures, and the morphology and microstructure will be characterized thoroughly by transmission electron microscopy (TEM) techniques. Calorimetric measurements will investigate the thermodynamic stability of Y-Ti-O nanoparticles as a function of size, irradiation, and temperature. Atomistic computer simulations, including first principles calculations, classical molecular dynamics and kinetic Monte Carlo simulations, will probe synergistic effects of radiation and temperature on the structural evolution of oxide nanoparticles and their defect behavior. This fundamental understanding will reveal the underlying physics and chemistry that govern phase stability and defect behavior of Y-Ti-O nanoparticles and establish the basis for developing predictive models of how nanostructured materials behave under extreme conditions of intense radiation and high temperature. Based on such fundamental understanding, new science will evolve to design strategy in materials processing for strengthening of alloys by oxide nanoparticles.

NON-TECHNICAL DESCRIPTION: Radiation-tolerant materials can extend the lifetime of components, and may be very valuable in the design and operation of safer, more reliable nuclear systems - where controlling radiation is a top priority. The atomic-level understanding of radiation interaction is critical for developing advanced materials that can withstand intensive radiation for both current and future nuclear technologies. This CAREER project targets the fundamental understanding of the behavior of nanostructured ceramics under extreme radiation environments. This fundamental knowledge may enable new science for nanoscale materials design that extends the performance of materials with excellent radiation tolerance. The research effort is complemented by an integrated education component which will impact the scientific community by bridging advanced materials and nanotechnology with nuclear education and training of young scientists in the critical area of controlling radiation. Special efforts will be made to involve underrepresented groups of high-school students and teachers through collaborations with local communities (Half Hollow Hills school district, NY) and academic outreach programs (including Summer@Rensselaer). This approach will help promote the general public's understanding of nuclear radiation (both the challenges and materials solutions).

TECHNICAL DETAILS: This CAREER project aims to elucidate atomistic mechanisms of radiation interaction and defect behaviors in order to understand the damage mechanisms and structural evolution of nanostructured ceramics and how different length scales affect materials radiation performance. This research builds on a synergetic effort of synthesizing nanostructured ceramics, energetic beam irradiation and the combination of state-of-the-art approaches (including advanced transmission electron microscopy (TEM) and ion beam techniques) in characterizing materials structural evolution and defect behaviors. High-temperature oxide melt solution calorimetry is being performed on nanostructured ceramics in order to correlate the thermodynamic understanding with radiation stability. The atomistic mechanisms of radiation interaction with nanostructured ceramics alongside multi-scale computational simulations based on DFT, classical molecular dynamic (MD) and kinetic Monte Carlo (kMC) are being used to determine how nanostructure evolves upon radiation. Based on an improved fundamental understanding, new science is evolving to develop advanced materials with enhanced radiation tolerance for effective radiation control through nanoscale materials design.

Innovative thermal management solutions to address ever-increasing challenges of heat generation are critical for future higher power, more compact and ultra-lightweight electronics. Current state-of-the-art materials such as flexible graphitic films for thermal management of high power electronics are not cost-effective since they are expensive to manufacture. Graphene, a single layer of carbon atoms bonded in a hexagonal lattice, is one of the thinnest and strongest of materials, and also displays intrinsically exceptional thermal conductivity. Macroscopic graphene structures, assembled from single layer graphene nanosheets, offer immense potential as advanced materials for effective thermal management. However, key challenges exist for the scalable assembly of two-dimensional graphene nanosheets into three-dimensional macroscopic structures, which is usually accompanied by a significant reduction of the thermal properties. To find solutions to address these key challenges, this award supports fundamental nano-scale manufacturing science of effectively assembling graphene nanosheets into large-scale three-dimensional architectures that are designed for performance in a cost-effective manner. These assembled macroscopic structures are highly flexible, mechanically robust and exceptionally thermal conductive, unlocking the enormous commercial potential of graphene as advanced materials for nano-scale thermal management. The results from this project will benefit the US economy and society. This project has synergistic educational and outreach impacts through integration of research and education and engaging participation of underrepresented groups.

This project will develop innovative approaches of integrating two well-established industrial processes of electrospray deposition and roll-to-roll processing for manufacturing flexible graphene papers with breakthrough thermal properties. The research will establish process-microstructure-property relationships in electrospray deposited and assembled graphene papers through experimentation. Post-assembly high temperature annealing and mechanical compaction for microstructural optimization and graphene sheet alignment will be performed in order to improve properties. A game-changer is the direct manufacturing of the graphene nanosheets from defect-free graphene using electrospray deposition. Superior properties will be achieved in the macroscopic graphene structure without the penalty of traditional energy-intensive high temperature annealing. The scalable and cost-effective approach developed in assembling two-dimensional nanosheets into three-dimensional functional architectures will have a broader impact on controllable assembly and design of functional architectures of other two-dimensional single atomic layer materials beyond graphene.

NON-TECHNICAL DESCRIPTION: A new type of carbon fibers assembled from two-dimensional graphene sheets was recently developed with higher thermal conductivity, but with inferior mechanical properties in comparison to conventional carbon fibers. The internal structure of the graphene fibers is not well characterized and the concomitant impact on thermal-mechanical properties are not fully understood. This project targets fundamental understanding of the inner fiber structure with a focus on molecular orientation and macroscopic ordering and establishing the process-structure-property correlation. These insights may enable the development of high performance graphene fibers and unlock their potential for technology applications, e.g., as structural components in fiber-reinforced composites. New fiber structures and properties, cost-effective and environmentally-benign production, and workforce development are critical for competitiveness in innovation and manufacturing in carbon fiber industries. This project engages high-school, undergraduate and graduate students in research. Special efforts are made to involve underrepresented groups of high-school students through collaborations with local communities and academic outreach activities (including Summer@Rensselaer).

TECHNICAL DETAILS: The proposed project is based on the conventional wisdoms for carbon fibers in which the fiber structure, particularly molecular orientation of graphene sheets, graphitic domains and their macroscopic ordering determine mechanical strength, Young's modulus, and thermal/electrical properties. To achieve a fundamental understanding of the fiber structure and establish the process-structure-property correlation, molecular orientation of the graphene oxide colloidal solution and the precursor graphene oxide fiber is investigated during fluid flow-assisted assembly. Macroscopic ordering of the graphene fibers is controlled by post fabrication carbonization and graphitization. Their impact on thermal-mechanical properties are being explored. By controlling the fluid flow-assisted assembly process and optimizing fiber structures, properties of the macroscopic graphene fibers can be dramatically improved. The microfluidics-enabled assembly of two-dimensional graphene sheets may enable new science for fabricating high performance carbon fibers.

Environmental barrier coatings (EBCs) are key components that can greatly enhance the performance/longevity of structural materials such as ceramic-matrix composites against active oxidation in high speed hot gas streams and corrosion in reactive engine environments. Multi-generation EBCs have evolved, mainly based on silicate-based systems, but they suffer from the volatility of silicon due to water vapor attack and corrosion of molten glass attack. Innovative design and discovery of EBCs with transformative performance are needed to meet even harsher environments of high temperature, high thermal flux and severe oxidation and corrosion for future aerospace and space systems. This Designing Materials to Revolutionize and Engineer our Future (DMREF) project will explore an innovative concept of using multiple component rare-earth phosphates as advanced EBCs, and develop a science-based paradigm guided by machine learning (ML) for accelerated materials design and discovery. Both graduate and undergraduate students will be trained as the next-generation workforce in this data-driven materials research. K-12 students and underrepresented groups will be engaged through multiple outreach activities such as the Engineering Summer Exploration program at Rensselaer and the New Visions: Math, Engineering, Technology & Science program. Materials data and computational tools developed will be contributed to the MPContribs Portal for public access on the Materials Project platform to facilitate data-driven material design.

Material design and discovery for advanced environmental barrier coatings (EBCs) have been greatly hindered by our limited understanding of how composition and microstructure affect materials properties and performance. This project will accelerate fundamental understanding of the influence of composition and microstructure on the phase stability and properties of multicomponent rare-earth phosphates, and use this understanding to optimize performance of next generation EBCs for ceramic matrix composites (CMCs) in reactive engine environments. A multipronged data-driven machine learning (ML) approach will be developed to inform materials design and guide materials performance evaluation to discover new rare-earth phosphates that have unique attributes of EBCs for CMCs, compared to current state-of-the-art disilicates without the issue of silicon evaporation. An element-based ML will be trained on high throughput density functional theory calculations and will be used to guide the design and optimization of configurationally-disordered rare-earth phosphates with key characteristics of EBCs. A microstructure-based ML will be trained on high-throughput finite element method calculations and will be used to predict the optimal microstructure and performance of EBCs against molten glass corrosion at elevated temperatures. The integration of multiscale computations, machine learning, and experimental demonstration and validation will provide a pathway for success in accelerating the design and discovery of rare-earth phosphates as next generation EBCs for CMCs.

This project is jointly funded by NSF’s Mathematical and Physical Sciences (MPS) Division of Materials Research (DMR) Designing Materials to Revolutionize and Engineer our Future (DMREF) program, and the Division of Civil, Mechanical, and Manufacturing Innovation (CMMI) in the Directorate for Engineering (ENG).

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.