Highlights
- High-voltage micro-CT extends nondestructive 3D imaging to dense, high-mass samples such as metal additive-manufactured parts, battery assemblies, and electronic components by using X-ray energies up to 225 kV.
- A combination of high penetration power, a large-area detector, flexible magnification, and a high-capacity sample stage enables imaging from micrometer-scale internal features to objects as large as 600 mm in diameter, 1200 mm tall, and 50 kg.
- CT data can support more than defect detection: reconstructed volumes can be segmented, dimensionally analyzed, quantified for void content, and converted into models for mechanical simulations based on the actual manufactured structure.
Summary
X-ray computed tomography provides nondestructive three-dimensional visualization of internal structures, allowing dense or complex objects to be examined without sectioning or extensive sample preparation. Unlike optical microscopy or SEM, which primarily examine exposed surfaces or prepared cross-sections, CT reconstructs the full internal volume and can identify pores, cracks, voids, delamination, misalignment, leakage, and other structural abnormalities.
For absorption-based CT, penetration and contrast depend strongly on sample thickness, density, elemental composition, and X-ray photon energy. Dense, thick materials containing relatively high-atomic-number elements absorb X-rays more strongly and therefore require higher-energy radiation to obtain usable transmitted intensity. This becomes particularly important for emerging applications involving lithium-ion battery assemblies, electronic circuitry, and metal additive manufacturing, where high-density materials and substantial sample dimensions are common.
A high-voltage micro-CT configuration using a 225 kV, 300 W X-ray source addresses these requirements. The system combines a minimum X-ray source focus size of 3 µm with a 434 × 434 mm flat-panel detector, variable source-to-object and source-to-detector distances, and a high-precision direct-drive rotation stage. It provides fields of view from approximately 4 to 350 mm, a minimum voxel size of 1.5 µm, and demonstrated spatial resolution of 3 µm. The large sample chamber also permits automated sample handling and customized experimental configurations.
Higher tube voltage is especially important for suppressing beam-hardening artifacts in dense materials. Comparison of high- and lower-voltage scans of an Inconel superalloy structure showed that 225 kV operation produced clearer internal contrast and substantially reduced artifacts compared with 130 kV imaging. In some applications, similar signal-to-noise performance can also be obtained at shorter exposure times.
For an additively manufactured Inconel structure, 200 kV imaging generated sufficient grayscale contrast to segment the solid material through relatively simple thresholding. The reconstructed volume was subsequently used to map structural thickness throughout the internal lattice. The same CT-derived geometry could be converted into a surface mesh and subjected to mechanical load simulation, demonstrating how CT can connect the actual manufactured component with a virtual engineering model rather than relying exclusively on its nominal CAD geometry.
High-voltage CT is also applicable to battery and electronics inspection. Imaging of a lithium-ion battery protection board resolved MOSFET wiring and connections approximately 40 µm and 125 µm in dimension, as well as features such as a solder layer of roughly 21 µm and a board layer of about 32 µm. Three-dimensional segmentation of solder joints allowed internal voids to be located and their volumes quantified from voxel counts. This illustrates how CT can provide both qualitative visualization and quantitative defect analysis in assembled battery components without physically dismantling them.
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