Using Micro-CT Scanning to Quantitative Characterize Porosity in High Pressure Die Castings and Semi-Solid Castings

2022 ◽  
Vol 327 ◽  
pp. 33-44
Author(s):  
Stephen P. Midson
Keyword(s):  
High Pressure ◽  
Total Porosity ◽  
Ct Scanning ◽  
Quantitative Information ◽  
X Rays ◽  
Micro Ct ◽  
Resolution Limit ◽  
Aluminum Castings ◽  
Semi Solid ◽  
Die Castings

Porosity is one of the main defects that limits the performance of castings. Porosity in aluminum castings can originate from several sources, including the volumetric shrinkage occurring during solidification, the precipitation of dissolved hydrogen, and entrapment of gasses such as air, boiling water, vaporized lubricants, etc. Traditional methods of identifying and measuring porosity in castings include 2D x-rays, sectioning and polishing, and Archimedes density measurements, but none of these provide a satisfactory quantitative estimate of the size, total volume and distribution of the pores. X-ray CT scanning is a relatively new method that generates not only a 3-dimensional view of the size and distribution of the pores, but can also provide quantitative information of the volume, surface area, size, shape and position of each pore within a casting. Micro-CT scanning is a specialized sub-category of CT scanning, which provides excellent resolution of fine porosity (a resolution limit of 4 microns in one of the case-stores presented in this paper), but it should be noted that the resolution limit in CT scanning techniques is related to sample size. This paper describes results from micro-CT scanning studies of two high pressure die castings and a semi-solid casting, and provides quantitative data on the total porosity content, and the porosity distribution. The paper will also demonstrate the capabilities of the micro-CT scanning process to provide a quantitative comparison of the porosity content in these different types of aluminum castings.

scholarly journals Finding fossils in Malapa breccia – medical CT scanning or micro-CT scanning?

2017 ◽  
Vol 113 (11/12) ◽  
Author(s):  
Jacqueline S. Smilg
Keyword(s):  
Computed Tomography ◽  
Lower Energy ◽  
Ct Scanning ◽  
Cost Effective ◽  
High Energy ◽  
X Rays ◽  
Micro Ct ◽  
X Ray ◽  
Mechanical Preparation ◽  
X Ray Computed

Computed tomography (CT) imaging of fossils has revolutionised the field of palaeontology, allowing researchers to gain a better understanding of fossil anatomy, preservation and conservation. Micro focus X-ray computed tomography (μXCT) has been far more extensively used for these purposes than medical CT (XCT) – mostly because of the exquisite detail that the μXCT scanning modality, using slices of micron thicknesses, can produce. High energy X-rays can potentially penetrate breccia more effectively than lower energy beams. This study demonstrates that lower energy beams produce superior images for prioritising breccia for preparation. Additionally, XCT scanners are numerous, accessible, fast and relatively cost-effective when compared to μXCT scanners – the latter are not freely available, scanning times are much longer and there are significant limitations on the size and weight of scannable objects. Breccia blocks from Malapa were scanned at high and lower energy and images were analysed for image quality, artifact and certainty of diagnosis. Results show that lower energy images are deemed superior to higher energy images for this particular application. This finding, taken together with the limitations associated with the use of μXCT for the imaging of the large breccia from Malapa, shows that XCT is the better modality for this specific application. The ability to choose fossil-bearing breccia, ahead of manual mechanical preparation by laboratory technicians, would allow for the optimal use of limited resources, manual preparatory skills as well as the curtailment of costs.

THINCASTTM; Providing Strong, Lightweight Castings for Automobiles and Other Applications

2014 ◽  
Vol 217-218 ◽  
pp. 294-301
Author(s):  
Alois Franke ◽  
John L. Jorstad
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
Die Casting ◽  
Casting Process ◽  
Engineering Properties ◽  
Traditional Process ◽  
Semi Solid ◽  
Die Castings ◽  
New Applications

Aluminium Rheinfelden has improved the competitiveness of semi solid processing by developing a casting process & alloy combination that is capable of ultra thin, ultra light parts having attractive engineering properties without need for full heat treatment. The THINCASTTM rheocasting process, together with Rheinfeldens Magsimal-59 alloy has been demonstrated capable of producing moderate sized castings with only 1-2 mm wall sections, thus providing a 30-50% reduction in traditional-process part weight. THINCASTTM can be adapted to a variety of die casting machines and will enable competitively improving the quality of conventional high pressure die castings as well as creating entirely new applications.

scholarly journals Soft tissue discrimination with contrast agents using micro-CT scanning

2020 ◽  
Vol 144 (1) ◽  
Author(s):  
Emilie Descamps ◽  
Alicja Sochacka ◽  
Barbara De Kegel ◽  
Denis Van Loo ◽  
Luc Van Hoorebeke ◽  
...  
Keyword(s):  
High Resolution ◽  
Soft Tissue ◽  
Contrast Agents ◽  
Soft Tissues ◽  
Life Sciences ◽  
Ct Scanning ◽  
Model Organisms ◽  
X Rays ◽  
Micro Ct ◽  
Organ Systems

The use of high resolution, three-dimensional visualization has been receiving growing interest within life sciences, with non-invasive imaging tools becoming more readily accessible. Although initially useful for visualizing mineralized tissues, recent developments are promising for studying soft tissues as well. Especially for micro-CT scanning, several X-ray contrast enhancers are performant in sufficiently contrasting soft tissue organ systems by a different attenuation strength of X-rays. Overall visualization of soft tissue organs has proven to be possible, although the tissue-specific capacities of these enhancers remain unclear. In this study, we tested several contrast agents for their usefulness to discriminate between tissue types and organs, using three model organisms (mouse, zebrafish and Xenopus). Specimens were stained with osmium tetroxide (OsO4), phosphomolybdic acid (PMA) and phosphotungstic acid (PTA), and were scanned using high resolution microtomography. The contrasting potentials between tissue types and organs are described based on volume renderings and virtual sections. In general, PTA and PMA appeared to allow better discrimination. Especially epithelial structures, cell-dense brain regions, liver, lung and blood could be easily distinguished. The PMA yielded the best results, allowing discrimination even at the level of cell layers. Our results show that those staining techniques combined with micro-CT imaging have good potential for use in future research in life sciences.

scholarly journals Skull shape differentiation of black and white olms (Proteus anguinus anguinus and Proteus a. parkelj): an exploratory analysis with micro-CT scanning

2013 ◽  
Vol 82 (2) ◽  
pp. 107-114 ◽  
Author(s):  
Ana Ivanović ◽  
Gregor Aljančič ◽  
Jan W. Arntzen
Keyword(s):  
Morphological Differentiation ◽  
Ct Scanning ◽  
Exploratory Analysis ◽  
Micro Ct ◽  
Black And White ◽  
Necturus Maculosus ◽  
Proteus Anguinus ◽  
Evolutionary Trajectories ◽  
Morphological Detail ◽  
Shape Changes

We performed an exploratory analysis of the morphology of the cranium in the white olm (Proteus anguinus anguinus) and the black olm (P. a. parkelj) with micro-CT scanning and geometric morphometrics. The mudpuppy (Necturus maculosus) was used as an outgroup. The black olm falls outside the white olm morphospace by a markedly wider skull, shorter vomers which are positioned further apart and by laterally positioned squamosals and quadrates relative to the palate (the shape of the buccal cavity). On account of its robust skull with more developed premaxillae a shorter otico-occipital region, the black olm is positioned closer to Necturus than are the studied specimens of the white olm. The elongated skull of the white olm, with an anteriorly positioned jaw articulation point, could be regarded as an adaptation for improved feeding success, possibly compensating for lack of vision. As yet, the alternative explanations on the evolution of troglomorphism in Proteus are an extensive convergence in white olms versus the reverse evolution towards less troglomorphic character states in the black olm. To further understand the evolutionary trajectories within Proteus we highlight the following hypotheses for future testing: i) morphological differentiation is smaller within than between genetically differentiated white olm lineages, and ii) ontogenetic shape changes are congruent with the shape changes between lineages. We anticipate that the morphological detail and analytical power that come with the techniques we here employed will assist us in this task.

scholarly journals A Microcomputed Tomographic Evaluation of Root Canal Morphology of Maxillary Second Premolars in a Pakistani Cohort

2021 ◽  
Vol 11 (11) ◽  
pp. 5086
Author(s):  
Mazen F. Alkahtany ◽  
Saqib Ali ◽  
Abdul Khabeer ◽  
Shafqat A. Shah ◽  
Khalid H. Almadi ◽  
...  
Keyword(s):  
Root Canal ◽  
Three Dimensional ◽  
Ct Scanning ◽  
Micro Ct ◽  
Single Root ◽  
Root Canal Morphology ◽  
Spss Software ◽  
Variable Morphology ◽  
Canal Morphology

This study aimed to investigate variations in the root canal morphology of maxillary second premolar (MSP) teeth using microcomputed tomography (micro-CT). Sixty (N = 60) human extracted MSPs were collected and prepared for micro-CT scanning. The duration for scanning a single sample ranged between 30 and 40 min and a three-dimensional (3-D) image was obtained for all the MSPs. The images were evaluated by a single observer who recorded the canal morphology type, number of roots, canal orifices, apical foramina(s), apical delta(s), and accessory canals. The root canal configuration was categorized in agreement with Vertucci’s classification, and any configuration not in agreement with Vertucci’s classification was reported as an “additional canal configuration”. Descriptive statistics (such as mean percentages) were calculated using SPSS software. The most common types agreeing with Vertucci’s classification (in order of highest to lowest incidence) were types I, III, V, VII, II, and VI. The teeth also exhibited four additional configurations that were different from Vertucci’s classification: types 2-3, 1-2-3, 2-1-2-1, and 1-2-1-3. A single root was found in 96.7% and the majority of the samples demonstrated two canals (73.3%). Further, 80% of the teeth showed one canal orifice. The number of apical foramina’s in the teeth was variable, with 56.7% having solitary apical foramen. The accessory canal was found in 33.3%, and apical delta was found in only 20% of the samples. Variable morphology of the MSPs was detected in our study. The canal configuration most prevalent was type 1; however, the results also revealed some additional canal types.

scholarly journals Timing of Mouse Molar Formation Is Independent of Jaw Length Including Retromolar Space

2021 ◽  
Vol 9 (1) ◽  
pp. 8
Author(s):  
Daisy (Jihyung) Ko ◽  
Tess Kelly ◽  
Lacey Thompson ◽  
Jasmene K. Uppal ◽  
Nasim Rostampour ◽  
...  
Keyword(s):  
Onset Time ◽  
Ct Scanning ◽  
Micro Ct ◽  
Third Molars ◽  
Developmental Duration ◽  
Dental Lamina ◽  
Permanent Molars ◽  
Dental Epithelium ◽  
Space Conditions

For humans and other mammals to eat effectively, teeth must develop properly inside the jaw. Deciphering craniodental integration is central to explaining the timely formation of permanent molars, including third molars which are often impacted in humans, and to clarifying how teeth and jaws fit, function and evolve together. A factor long-posited to influence molar onset time is the jaw space available for each molar organ to form within. Here, we tested whether each successive molar initiates only after a minimum threshold of space is created via jaw growth. We used synchrotron-based micro-CT scanning to assess developing molars in situ within jaws of C57BL/6J mice aged E10 to P32, encompassing molar onset to emergence. We compared total jaw, retromolar and molar lengths, and molar onset times, between upper and lower jaws. Initiation time and developmental duration were comparable between molar upper and lower counterparts despite shorter, slower-growing retromolar space in the upper jaw, and despite size differences between upper and lower molars. Timing of molar formation appears unmoved by jaw length including space. Conditions within the dental lamina likely influence molar onset much more than surrounding jaw tissues. We theorize that molar initiation is contingent on sufficient surface area for the physical reorganization of dental epithelium and its invagination of underlying mesenchyme.

scholarly journals Dual-Energy Computed Tomography of the Liver: Uses in Clinical Practices and Applications

Diagnostics ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 161
Author(s):  
Masakatsu Tsurusaki ◽  
Keitaro Sofue ◽  
Masatoshi Hori ◽  
Kosuke Sasaki ◽  
Kazunari Ishii ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Liver Tumors ◽  
Energy Levels ◽  
Ct Scanning ◽  
Dual Energy ◽  
Liver Imaging ◽  
X Rays ◽  
Clinical Practices ◽  
Dual Energy Computed Tomography ◽  
Noise Ratio

Dual-energy computed tomography (DECT) is an imaging technique based on data acquisition at two different energy settings. Recent advances in CT have allowed data acquisitions and simultaneous analyses of X-rays at two energy levels, and have resulted in novel developments in the field of abdominal imaging. The use of low and high X-ray tube voltages in DECT provide fused images that improve the detection of liver tumors owing to the higher contrast-to-noise ratio (CNR) of the tumor compared with the liver. The use of contrast agents in CT scanning improves image quality by enhancing the CNR and signal-to-noise ratio while reducing beam-hardening artifacts. DECT can improve detection and characterization of hepatic abnormalities, including mass lesions. The technique can also be used for the diagnosis of steatosis and iron overload. This article reviews and illustrates the different applications of DECT in liver imaging.

A Study of the Effect of Extended Hounsfield Unit Range and Voxel Size on Defect Detection in Friction Stir Welds

2020 ◽  
Author(s):  
Ahmad M. R. Baydoun ◽  
Ramsey F. Hamade
Keyword(s):  
Gamma Rays ◽  
Dissimilar Materials ◽  
Hounsfield Unit ◽  
Ct Scanning ◽  
Ultrasonic Waves ◽  
X Rays ◽  
Internal Defects ◽  
Voxel Size ◽  
X Ray ◽  
Friction Stir

Abstract Friction stir welding (FSW) is a novel welding method that is garnering attention, in part, due to its ability to join dissimilar materials. One of the challenges in producing dissimilar friction welded joints is ensuring the welds are defect-free. Nondestructive testing (NDT) methods such as ultrasonic waves, gamma rays, X-rays, and X-ray CT, are gaining popularity as a method to detect internal defects in FSW joints. In this study, dissimilar AA1050-AA6061-T6 FSW lap welds are Manufactured and then examined using an NDT X-ray CT technique. The effects of two critical X-ray CT scanning parameters (voxel size and Hounsfield unit (HU)) on the detection of internal defects are investigated. The samples are scanned via X-ray CT at two different voxel sizes (2.457 E−02 and 1.420 E−03 mm3) and two HU ranges (12-bit and 16-bit depth). The generated Digital Imaging and Communications in Medicine (DICOM) images are segmented based on a proper HU threshold found via the Otsu thresholding method. The findings show that Small voxel size (higher resolution) improves the ability of detecting internal defects and improves the effectiveness of the thresholding process. Higher HU range results in a wider separation between detected material peaks, thus enhancing the effectiveness of the thresholding process as well.

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