Additive manufacturing powder feedstock characterization using X-ray tomography

Abstract

To answer the need for efficient quality control protocols for additive manufacturing processes and materials, specific testing methods for powder feedstocks should be developed. A powder feedstock may contain some defects, such as porosities, that will remain in the final parts after the building process. X-ray tomography combined with 3D image analysis offers unique advantages over other characterization methods, such as pycnometry and metallography, in respect to quantifying internal porosity in the individual particles of the feedstock. This paper presents the effect of X-ray tomography parameters on the quality of the obtained images and its impact on the image analysis. An automated image analysis routine was also developed to allow the visualization of the pores inside the particles but also, more importantly, to quantify this internal porosity contents, as well as to provide information on the morphological features of these pores, such a size distribution, number of particles containing pores and the volume fraction of a pore inside a particle.

Standard method for microCT-based additive manufacturing quality control 4: Metal powder analysis

“…This allows stability and ease of mounting of the sample in the microCT instrument for high magnification. The same authors more recently extended this work to smaller powders and scan resolution down to 0.7 μm [8]. This paper describes a workflow for obtaining powder porosity by microCT but the description for obtaining particle size distribution is not clear, and the procedure makes use of user-dependant procedures for de-noising and thresholding.…”

X-Ray Microcomputed Tomography in Additive Manufacturing: A Review of the Current Technology and Applications

“…The analysis of metal powders has recently become possible using high-resolution microCT, as demonstrated in Refs. 92,93 The usefulness of this over conventional laser diffraction or microscopy is primarily that internal pores can be easily identified in powders, which might be trapped in the meltpool during the AM process. 45 It is also the only method through which the real sphericity, volume, and surface areas of particles can be determined, which can all be important parameters for ensuring flowability and eventually quality of the powder bed.…”

A Review of Particle Size Analysis with X-ray CT

“…Over the last 20 years ( Figure 1 a), more than 60 publications [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 ,…”

“…The digital data, collected with each scan, can feed directly into computed models about the particles and their behaviour in the granular assembly [ 27 , 47 , 48 , 54 ]. After early use of synchrotron beam lines [ 1 , 3 , 6 , 7 , 14 , 28 , 33 , 34 , 46 ], the emergence of laboratory X-ray CT instruments [ 2 , 4 , 8 , 9 , 10 , 11 , 12 , 13 , 18 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 30 , 31 , 32 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 47 , 48 , 49 , 50 , 51 , 52 , 54 , 55 , 57 , 58 , …”