Additive manufacturing of copper enables enhanced design freedom which allows for improved performance of components in thermal management and electrical applications. Joining via soldering provides ...ideal electrical and thermal connections, but the solderability of complex additively manufactured surfaces is poorly understood. In the present work, the solderability of nominally pure copper coupons manufactured by three additive manufacturing techniques (laser powder bed fusion, laser engineered net shaping, and bound powder extrusion) was experimentally assessed using the wetting balance technique and pin pull testing. Coupons produced by each method were tested as built and after surface modification by dry electropolishing. Contact angles and wetting times were calculated from wettability testing. Peak tensile loads required to remove pins soldered to coupons were also recorded for each surface condition. The dipped coupons and solder joint fracture surfaces were examined with optical and scanning electron microscopes. It was found that nonuniform wetting and excessive wicking of solder can result in weak joints, and surface modification positively affected overall solderability in all cases. All surfaces were shown to be wettable, but bound powder extrusion was found to produce the most solderable copper surfaces among the additive manufacturing methods tested.
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•Decrease in IDR with an increase in chain length of the counterion observed using UV-imaging.•Developed interfacial area ratio (Sdr) showed significant surface gains for the compacts ...for IDR determination.•Particulates on surface compacts and observed cracks responsible for inflated IDR values.•Imaging of surface should be taken into consideration prior IDR determination.
The optimisation of the pharmaceutical properties of carboxylic acid drugs is often conducted by salt formation. Often, the salt with the best solubility is not chosen due to other factors such as stability, solubility, dissolution and bioavailability that are taken into consideration during the preformulation stage. This work uses advanced imaging techniques to give insights into the preformulation properties that can aid in the empirical approach often used in industry for the selection of salts. Gemfibrozil (GEM) was used as a model poorly soluble drug. Four salts of GEM were made using cyclopropylamine (CPROP), cyclobutylamine (CBUT), cyclopentylamine (CPENT) and cyclohexylamine (CHEX) as counterions. DSC, XRD and SEM were used to confirm and characterise salt formation. IDR obtained using UV-imaging up to 10 min for all the salts showed that an increase in the chain length of the counterion caused a decrease in the IDR. Past the 10 min mark, there was an increase in the IDR value for the CPROP salt, which was visualised using UV-imaging. The developed interfacial (surface) area ratio (Sdr) showed significant surface gains for the compacts. Full dosage form (capsule) imaging showed an improvement over the GEM for all the salts with an increase in chain length of the counterion bringing about a decrease in dissolution which correlated with the obtained UV-imaging IDR data.
Remarkable interfacial behaviors are observed in nature. Our efforts, directed toward replicating the structures, chemistries, and therefore functional properties of natural nonwetting surfaces, are ...competing with the result of billions of years of natural selection. The application of man-made surfaces is challenged by their poor longevity in aggressive environmental or applied service conditions. This study reports on a new approach for the creation of multiscale hierarchical surface patterns in metals, which exploits thermodynamic phenomena in advanced manufacturing processes. While hydrophobic coatings can be produced with relative ease by electrodeposition, these fractal-type structures tend to have poor structural integrity and hence are not durable. In this method, “seed surfaces” are directly written onto substrates by selective electrodeposition, after which they are irradiated by a large-area, pulsed electron beam to invoke a beading phenomenon, which is studied here. The length scale of these beads is shown to depend upon the melt time of the liquid metal. The created surfaces are shown to yield high water contact angles (145°) without subsequent chemical modification, and high adhesion properties reminiscent of the “rose petal” hydrophobic effect. The size and morphology and hence the hydrophobic effect of the surface beads generated are correlated with the thickness of the electrodeposited coating and hence the melt lifetime upon electron irradiation. This new rapid approach for tunable hydrophobic surface creation has applications for developing precision hydrophobic patterns and is insensitive to surface complexity.
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•Influence of the stress ratio and the cycles to failure on the fracture surface.•Surface morphology parameters in fatigue cracks context.•Analysis of area field and fractal ...characterization.•The surface tests analyzed on the entire fracture surfaces.•Dependence in the surface fracture parameters on the crack growth.
This work deals with the post-failure analysis of the fatigued fracture in the context of surface topography parameters. The influence of material isotropy on fatigue fractures using metrological methods is presented. The study was carried out on fracture surfaces of different maximum stress at the notch root σmax and stress ratio R. Surface topography and fracture measurements were made using the Infinite Focus technique with the use of the changing the focus, which allowed the collection of data sets. The analysis of the geometric product specification was performed by means of height parameters according to ISO 25178, fractal dimensions as well as surface isotropy. Paper presents that higher values of skewness were received for the stress ratios R = −1, −0.5 than for R = 0, while lower kurtosis values for the stress ratios R = −1 and −0.5 than for R = 0 were observed.
In 3D printing, as in other manufacturing processes, there is a push for zero-defect manufacturing, mainly to avoid waste. To evaluate the quality of the printed parts during the printing process, an ...accurate 3D measurement method is required. By scanning the part during the buildup, potential nonconformities to tolerances can be detected early on and the printing process could be adjusted to avoid scrapping the part. Out of many, shape-from-focus, is an accurate method for recovering 3D shapes from objects. However, the state-of-the-art implementation of the method requires the object to be stationary during a measurement. This does not reconcile with the nature of 3D printing, where continuous motion is required for the manufacturing process. This research presents a novel methodology that allows shape-from-focus to be used in a continuous scanning motion, thus making it possible to apply it to the 3D manufacturing process. By controlling the camera trigger and a tunable lens with synchronous signals, a stack of images can be created while the camera or the object is in motion. These images can be re-aligned and then used to create a 3D depth image. The impact on the quality of the 3D measurement was tested by analytically comparing the quality of a scan using the traditional stationary method and of the proposed method to a known reference. The results demonstrate a 1.22% degradation in the measurement error.
In the literature, wear damage of hip prostheses is typically expressed as volumetric wear. Details on wear distribution are rarely provided despite being fundamental to better understand the ...damaging process and improve implant design.
This study presents a preliminary experimental investigation on the evolution of the wear map of hip replacements during wear testing. A ceramic-on-UHMWPE hip prosthesis was tested in-vitro and wear maps of the cup surface were measured throughout the test in a novel way, combining focus variation microscope inspections to the replica method. Wear maps revealed important characteristics of the damaging process not highlighted by the standard gravimetric procedure such as worn area location and shape as well as the progress of local damages.
•Local information on wear distribution is demanded for hip implant improvement.•Wear map evolution of a ceramic-on-UHMWPE hip implant was monitored for the first time.•Wear maps were estimated combing focus variation microscope and replica method.•Wear maps show the evolution in shape and location of the wear damage during tests.•Profilometric and SEM analyses of the worn surface showed abrasive wear.
Micro gears represent key components in an increasing number of industry, applications. To satisfy the increasing quality requirements in terms of lifetime and noise emissions, new function oriented ...measurement strategies need to be implemented, that allow the deployment of Inline Quality Control Cycles. Therefore, a Design of Experiments (DoE) is conducted and the measurement uncertainty systematically evaluated in accordance to Guide to the Expression of Uncertainty of Measurement (GUM). Furthermore, this paper describes a method to optimize the tradeoff between measurement uncertainty and measurement time in optical metrology with a use case in micro gear measurement using focus variation. This optimization method uses a meta-model and hyperparameters to allow the adjustment to specific operating conditions and use cases.
•Focus variation microscopy used to measure edge angles on stone tools.•Results indicate the edges appear “smoother” at the largest scale of calculation.•Edge shows more detail and appears “rougher” ...as scale of calculation decreases.•Maximal edge curvature proved reliable at documenting stone tool edges.•Maximal edge curvature on stone tool edges increased with increased use duration.
The adoption of an agricultural lifeway is considered one of the most significant cultural events in prehistory. Microwear analysis of stone harvesting tools is among the many approaches used to document the transition to agriculture in the Near East. Traditionally, these microwear analyses rely on the use of optical microscopy and visual-verbal descriptions of wear criteria. In addition to traditional optical microscopy, ongoing research into the applications of surface metrology for the characterization of microwear traces has contributed to the development of quantitative microwear methods. Despite significant research into the quantification of lithic microwear polishes, there has been comparatively little research on the quantification of tool edge angles to understand function. In this paper, we test a new method for the quantification of areal curvature of stone harvesting tool edges at multiple scales using data collected with focus variation microscopy. These calculations are based on curvature tensors of the measured surface topographies along tool edge cross sections. This method allows calculation of maximal and minimal curvatures at each location and scale. For this paper, we analyze a set of experimental microliths used as cereal harvesting tools using changes in multiscalar areal edge curvature to mathematically document harvesting intensity (duration of use). This experimental research presents a new method for documenting used stone tool edges that will contribute to our understanding of how harvesting tools were used, curated, and discarded in the past, giving insight into the food collection practices of early farmers.
When using an areal measuring optical instrument to measure rough surfaces, especially surfaces generated by metal additive manufacturing (e.g. laser and electron beam powder bed fusion), ...topographical artifacts such as spikes on a reconstructed surface are nearly unavoidable. These artifacts may affect the determination of surface roughness parameters and lead to erroneous surface features. This paper proposes a new preprocessing method to eliminate most artifacts before extracting surface heights of rough surfaces measured by focus variation microscopy. In this method, the axial region where a surface height value is located with the highest probability is estimated, based on datasets of planes parallel to the axial scanning direction. Results regarding height measurements with and without the preprocessing method are compared by measuring a Rubert Microsurf 329 comparator test panel for reference and workpieces produced by metal additive manufacturing.
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