This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
The objective of this Major Research Instrumentation (MRI-R2) award is to acquire a high resolution x-ray tomography apparatus. A parallel computing cluster with associated software is acquired as part of the system for fast three-dimensional structure re-generation to accommodate the use by multiple researchers. A cooling stage will provide a constant temperature environment. A loading stage will allow in-situ observation of a sample under load.
The instrument will be accessed by multiple users on projects that require the ability to use non-destructive techniques to determine the microstructures as well as their evolution under deformations. The instrument will be made available to all users at the university, and industry in the region as well as in the nation. The equipment will help enhance the training of graduate and undergraduate students, including a substantial number of under-represented minority and women students, and will also support student projects at nearby high schools.
Numerous research projects have been carried out involving a wide range of materials such as silica aerogels, graphite foams, mice bones, polymer nanocomposites, ceramics, and metal foams. The understanding of these materials’ mechanical behavior and design require non-destructive characterization of their 3-dimensional (3-D) nanostructures and microstructures, and also the in-situ microstructural evolution for determining the relationship between structure and properties. To accomplish this, we have used a high resolution SkyScan 1172 micro-computed x-ray tomography (μ-CT) apparatus. The μ-CT has been accessed by multiple users on projects that require the ability to use non-destructive techniques to determine the 3-D nanostructures and microstructures as well as their evolution under mechanical deformations. The instrument has been made available to all users at the university, as well as other universities and industry in the region and beyond through UNT’s Center for Advanced Research and Technology, CART (http://research.unt.edu/cart/node/94). The equipment enhanced the training of graduate and undergraduate students, including a substantial number of under-represented minority and women students, and also supported local high school student learning through outreach activities including ASM Materials Camp (Summer 2011). Specific research outcomes and education activities using the μ-CT involved the following projects: 1) Quantitative x-ray tomography analysis of carbon-carbon foams coated with atomic layer deposited (ALD) tetragonal zirconia for thermal and wear protection management; 2) X-ray tomography analysis of mice bone and its use in determining nanomechanical properties; 3) Investigation of the internal microstructural change of a polymethacrylimide (PMI) foam using x-ray tomography; and 4) X-ray tomographic analysis of a cross-linked template silica aerogel. In regard to a major outcome of project 1), a 3-D X-ray μ-CT image in Figure 1 shows graphite foam coated with zirconium oxide (ZrO2) to a depth of 1.5 mm. The atomic-layer-deposition coating process is effective in coating subsurface pores to protect against heat and wear in aerospace applications, such as bushings in jet engines. In regard to project 2), the initial determination of protocols that would generate reliable X-ray tomography images was conducted on mice bone. It was determined that compared to values determined using the environmental scanning electron microscope, the standard deviation and range were significantly narrowed in using the μ-CT system. In regard to project 3), the experimental results show that μ-CT can successfully be used to perform 3-D displacement measurement on PMI foam at the microscale. By using μ-CT technique, we can further analyze the internal deformation and fracture behavior of PMI foam under different loading conditions. In regard to project 4), it was determined that the cross-linked aerogels have the ability for high energy absorption, due to the uniform deformation without forming a shear bonding zone.
