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Materials and processing for power electronics packaging and green technologies
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Spectrophotometric Detection of Nickel in Water by Lab-on-a-chip Technology: Application to Electroplating
Get PDFNickel is a metal member of the transition series in the periodic table, and as such shows outstanding properties interesting to the world of industry, namely corrosion resistance to air, water and alkali and electrical conductivity. In fact, nickel is widely employed in electroplating, where high analyte concentrations, up to 100g/L, are required to achieve excellent final results. The process monitoring is required not only to ensure constant and adequate metal-finishing concentration but also to guarantee the safety of wastewater products. To detect nickel, either in high and low metal concentration, a colorimetric method was selected. The spectrophotometric study reveals a well-defined absorption peak at 396nm, giving a calibration curve with remarkable linearity toward metal concentrations, ranging from 1 to 22g/L. By proper optimization process, the detection field can be simply enlarged at least from 100 g/L (100000ppm) to 3*10-3 g/L (3ppm). Due to the presence of an acid part in the electroplating bath, the behaviour of the metal in an acid solution has also been investigated, and the calibration curve still depicts a good linearity of the system.
Achieved results pointed out the suggested colorimetric method as a promising candidate for addressing the requirement for capillary and regular monitoring of nickel in water, throughout a wide range of concentrations.The laboratory method may be readily improved and adapted for microfluidic technology by lowering sample and reagent amounts, miniaturizing sensors, and automating the entire process, from sampling to data recover
Spectrophotometric Detection of Copper in Water by Lab-on-a-chip Technology: Application to Electroplating
Get PDFSustainable Manufacturing of Lightweight Hybrid Nanocomposites for Electric Vehicle Battery Enclosures
Get PDFNanocomposite laminates containing carbon fibers, epoxy, and multiwalled carbon nanotubes were fabricated using a vacuum bag process. Ecofriendly ionic liquid (5 wt%)-treated multiwalled carbon nanotubes (pristine and nickel-coated) were added to the epoxy independently, in amounts ranging from 1 wt% to 3 wt%, in order to tailor the mechanical, electrical, and thermal performance of manufactured carbon fiber epoxy composite laminates. These nanocomposite laminates were later characterized through flexural testing, dynamic mechanical analysis, impedance spectroscopy, thermal conductivity tests, and FTIR spectroscopy to evaluate their suitability for battery pack applications. The findings showed that both types of multiwalled carbon nanotubes exhibited multifaceted effects on the properties of bulk hybrid carbon fiber epoxy nanocomposite laminates. For instance, the flexural strength of the composites containing 3.0 wt% of ionic liquid-treated pristine multiwalled carbon nanotubes reached 802.8 MPa, the flexural modulus was 88.21 GPa, and the storage modulus was 18.2 GPa, while the loss modulus peaked at 1.76 GPa. The thermal conductivity of the composites ranged from 0.38869 W/(m · K) to 0.69772 W/(m · K), and the electrical resistance decreased significantly with the addition of MWCNTs, reaching a minimum of 29.89 Ω for CFRPIP-1.5 wt%. The structural performance of hybrid nanocomposites containing ionic liquid-treated pristine multiwalled carbon nanotubes was higher than that of the hybrid nanocomposite of ionic liquid-treated Ni-coated multiwalled carbon nanotubes, although the latter was found to possess better functional performance
Routine Monitoring of Trace Arsenic in Water by Lab-on-a-chip Technology: a Preliminary Study
Get PDFWater contamination by Arsenic poses a serious risk for human health, due to its manifold toxic effects. The
concern is mainly for drinking water, regarded as the most imperative route of Arsenic exposure to human
beings. The maximum concentration limit for Arsenic in drinking water was fixed by World Health Organisation
(WHO) at 10 μg L−1 but in many developing nations it is increased to 50 μg L−1 due to economic constraints to
detect lower concentrations.
In this scenario, the design of an affordable Arsenic sensor, for routine monitoring of water, is crucial. The
answer to these requirements can be the lab-on–a-chip technology applied to a microfluidic device.
Available detection methods for Arsenic are investigated, focusing on their potential application on a portable
monitoring device: among them a colorimetric method, based on Rodamine B as indicator, and
chronopotentiometry were selected as suitable for the required purpose. Preliminary laboratory tests were aimed
to determine the limit of Arsenic concentration detectable by both the methods; the lower value of 1 μg L−1 was
detected by chronopotentiometry, in good agreement with the required resolution of the measurement.
Moreover, a process optimization adapted the method for the microfluidic technology.
Obtained results point out the new developing lab-on-a-chip technology as good candidate to address the need
for a capillary and frequent monitoring of Arsenic contamination of water by an easy and cheap portable device
Analysis of Quasi-Simultaneous Laser Welding in T-Joint Configuration for PMMA-ABS Using Circular Wobble Geometry
Get PDFThe focus of this study was the investigation of the quasi-simultaneous laser welding (QSW) technique of polymethyl methacrylate (PMMA) and acrylonitrile butadiene styrene (ABS) in a T-joint configuration using a circular wobble laser path. The main aim was to find how laser parameters, such as scanning speed, number of scans, and laser power, influence key indicators of weld quality: penetration depth and weld strength. A range of scanning speeds (1–2 m/s) and scan repetitions (20–70) was explored, with the goal of keeping the total welding time around 1 s, a time compatible with industrial mass production. The results demonstrated a clear correlation between linear energy density and penetration depth. Deeper penetrations were achieved at higher energy levels. Weld strength was maximized with a lower number of scans (20) and higher powers (above 130 W). The configuration offering the best combination of weld strength (1137 N) and total welding time (0.8 s) was identified, demonstrating the suitability of QSW for mass productio
Additive Manufacturing for Electronics (AME): Prototyping High Surface Area Substrates to Improve Thermal Performance
Get PDFNowadays, Additive Manufacturing for Electronics (AME) is gaining ground in device
fabrication for the numerous advantages of these types of manufacturing technologies,
such as fast production processes, freeform design, and low-cost prototyping. In this
scenario, the proposed research work is focused on evaluating an innovative strategy for a
common issue in power electronics, which is related to the generation of hotspots. To face
this problem, the 3D printing of ceramic substrates with different high surface areas was
studied to improve thermal dissipation. Together with improved thermal management, the
upper surface of the devices enabled the deposition of a desired conductive pattern and
the bonding of bare die components for device fabrication. Finally, thermal exchange was
monitored to verify the efficacy and efficiency of the devices’ dissipation capabilities. The
proposed models exhibited a 70% temperature reduction upon transitioning from air to
water. Furthermore, the operating temperature remained stable for 10 min, meeting the
specific requirements of the intended application
The role of porosity and acidity in the catalytic upcycling of polyethylene
Get PDFPlastics have become fundamental and widespread materials in our everyday life. Nowadays, the most demanded plastics are polyolefins, accounting for nearly half of the Global plastic production. However, the end-of-life disposal of these materials is an inevitably issue connected to their increased production. Among chemical recycling techniques, the most thoroughly investigated process is the catalytic pyrolysis, showing a vast panorama of different set-ups optimized for the major production of either gaseous or liquid compounds.
In this contribution a series of mesoporous silica-based materials, either pure SiO2 or substituted with Zr and Al, were systematically synthetized varying both porous framework and surface acidity, in the attempt of rationalizing the effect of each parameter (deeply characterized by physico-chemical methods) on the catalytic pyrolysis of linear low-density polyethylene (LLDPE). The synthetized materials together with some zeolites and aluminas reference samples were tested towards LLDPE degradation in a batch reactor set-up optimized for the formation and accumulation of the gaseous compounds, coupled with IR spectroscopy for in situ monitoring the evolution of the most abundant species (mostly propylene and branched C4-C6 olefins, together with a minor fraction of ethylene and short hydrocarbons). This work points out the necessity of the presence of Brønsted acid sites for a good activity (in terms of both the yield of gaseous products and lowering of the process temperature), but it also reveals a non-negligible role of the Lewis acid sites and it warns about the importance of controlling not only the amount of acid sites but also their strength
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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