Designs of high ductile high temperature ceramics with non-equilibrium defect framework
Abstract
High temperature ceramic (HTC) materials have been widely used for structural and various functional applications. However, most cer,amics have rather limited plasticity at low temperatures. A majority of ceramics fracture well before the onset of plastic yielding., The brittle nature of ceramics arises from the lack of dislocation activity and the need for high stress to nucleate dislocations.,To overcome these critical issues in ceramics, we propose a fundamental study to design highly ductile ceramic materials with strate,gically built non-equilibrium defect framework. More specifically, we plan to incorporate these non-equilibrium defects by (1) mecha,nical preloading to artificially build defect networks to enable ductile deformation; (2) nonequilibrium sintering process to incorp,orate highly uniform and high density defect network in ceramics to allow plastic deformation; (3) strategically engineering grain b,oundary and phase boundaries to enable phase transformation toughing mechanisms. The Novelty of the work lies in more universal appr,oaches to fundamentally tailor the bulk ceramic mechanical properties via incorporation of non-equilibrium defect framework in the b,ulk part of the HTC. Coupling withgrain boundary and phase boundary designs, we aim to further enhance the toughness of these HTC ma,terials. Multiple approaches are taken to address a wide range of ceramic materials since specific approaches might be more effectiv,e for some selected systems.Through these novel approaches and well-engineered non-equilibrium defect networks, we believe it is pos,sible to design highly ductile ceramics for various structural, functional and combined applications that will find unique applicati,ons for Navy ships and vehicles and, structural, optical and electronic components for hypersonic flights. This project will also in,tegrate in situ and ex situ mechanical testing approaches (e.g., in situ compression and tensile testing in SEM under elevated tempe,ratures) to study the fundamental mechanisms of mechanical deformability of ceramics with these novel non-equilibrium defect network,s and thus propose better defect designs. The short-term goal is to investigate the impact of dislocations, stacking faults, point d,efects, phase boundaries (PBs) and the framework of these defects on the enhancement of moderate temperature deformability of cerami,c materials. The long term goal is to enable the design of ductile ceramics for various engineering applications that are critical f,or Navy missions.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 16, 2022
- Source ID
- N000142212160
Entities
People
- Haiyan Wang
Organizations
- Office of Naval Research
- Purdue University
- United States Navy