Combining controlled magnetic fields and freeze casting for structured advanced ceramics and composites
Abstract
Synopsis This research aims to discern the basic knowledge to employ low-energy externally applied magnetic fields with the fabrication technique of freeze casting to create tailored porous and hierarchically structured ceramic materials and two-phase composites. We will combine hypothesis-driven empirical science with theoretical analysis to understand the integration of freeze casting of a wide variety of surface-magnetized ceramic materialsÑincluding diamagnetic (i.e., ÒnonmagneticÓ) Al2O3, paramagnetic TiO2, and ferrimagnetic Fe3O4, which represent many of the ceramics used in advanced materialsÑwithin a tri-axial Helmholtz coil that induces controlled, spatially uniform magnetic fields to create materials with tailored structural and mechanical properties at very low magnetic field strengths (= 10 mT) and low energies (and therefore relative costs). Such materials could be a game-changer for Army applications in terms of future advanced ceramics in armor, electronics, and robotics, all fabricated with low energy costs. Science problem and significance The need for processing methods to create ceramic and composite engineered materials with tailored properties that fit form to function has application throughout both science and industry. Existing processing techniques for such materials include additive manufacturing and mold-based methods. However, a shortcoming of each of these state-of-the-art methods is that the structure of the engineered materials can often only be controlled on a single length scale or have poor control at multiple length scales. In contrast, it is well-documented that the hierarchical structure of many multifunctional natural materials, such as bone, where both structural stability and nutrient storage are facilitated, is directly responsible for their properties. Therefore, the lack of hierarchical control of the microstructure of ceramic and composite engineered materials, along with theoretical understanding of this control, presents an important scientific problem that must be addressed. Research hypothesis We propose to discern the interactions between a wide variety of freeze-cast materials, representing a range of magnetic susceptibilities, and externally applied magnetic fields. To realize this, we will employ freeze casting of surface-magnetized colloidal suspensions in combination with controlled magnetic fields generated by a tri-axial Helmholtz coil to effect control of tailored structural ceramic materials at multiple length scales. The results will be interpreted using a theoretical analysis to develop an understanding of how magnetization of colloidal particles affects freeze-cast patterning. Therefore, this research will empirically and theoretically test the hypothesis that spatially uniform magnetic fieldsÑcontrolled in terms of strength and directionÑcan be applied to affect the structure of porous materials and two-phase composites made of surface-magnetized diamagnetic, paramagnetic, and ferrimagnetic materials through the freeze-casting process, enabling new materials that outperform their non-surface-magnetized freeze-cast counterparts in terms of mechanical properties along with theory of materials science that will inform future research into this and similar fields. These results can potentially be more broadly applied to influence interactions in a variety of similar fabrication techniques such as particle- and fiber-reinforced composites and metal-melt solidification, although that is beyond the scope of this project. This will be accomplished through fundamental scientific research (combining both experiments and theoretical modeling) into the use of static magnetic fields in a series of factorial studies of the following variables: (1) diamagnetic, paramagnetic, and ferrimagnetic base ceramic materials, (2) surface-magnetized and non-surface-magnetized states of these base ceramic materials, (3) magnetic field strength, and (4) magnetic field direction.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 24, 2023
- Source ID
- W911NF2110062
Entities
People
- Steven E Naleway
Organizations
- Army Contracting Command
- United States Army
- University of Utah