Electrodeposition of Pb and PbO2 on Graphite Felt in Membraneless Flow-Through Reactor: A Method to Prepare Lightweight Electrode Grids for Lead-Acid Batteries

One of the possible ways of mitigating the primary lead-acid battery downside—mass— is to replace the heavy lead grids that can add up to half of the total electrode’s mass. The grids can be exchanged for a lightweight, chemically inert, and conductive material such as graphite felt. To reduce carbon surface area, Pb/PbO2 can be electrochemically deposited on graphite felt. A flow-through reactor was applied to enhance penetration of adequate coverage of graphite felt fibers. Three types of electrolytes (acetate, nitrate, and methanesulfonate) and two additives (ligninsulfonate and Triton X-100) were tested. The prepared composite electrodes showed greater mechanical strength, up to 5 times lower electrical resistivity, and acted as Pb and PbO2 electrodes in sulfuric acid electrolytes.

Influence of Carbon Nanoparticles Additives on Nanosilver Joints in LTJT Technology

90% of High Temperature Electronic devices operate in temperatures in range from 150 to 300ºC and for such temperature needs, technologies typical for the military range might be adapted. To make it possible, new joining techniques are developed, one of which is use of pastes with silver nanoparticles sintered with Low Temperature Joining Technique. Silver sintered joints have three times higher thermal conductivity and five times lower electrical resistivity than typical solders, while being able to operate in temperatures reaching 350ºC. In current paper, the authors show the impact of additions of carbon nanoparticles on joints prepared in LTJT technology. The authors prove, that an addition of few percent of graphene nanoplatelets or carbon nanotubes improves joints mechanical, thermal and electrical properties, while ensuring proper rheology of pastes.

Performance of Cu–Ag Thin Films as Diffusion Barrier Layer

It is well-known that Cu–Sn intermetallic compounds are easily produced during reflow process and result in poor reliability of solder bump. Recently, amorphous metallic films have been considered to be the most effective barrier layer because of the absence of grain boundaries and immiscibility with copper. Since Cu–Ag alloys are characterized by their lower electrical resistivity and superior glass-forming ability, they are appropriate to be used as the diffusion barrier layers. In this study, molecular dynamics simulation was performed to investigate the effects of composition ratio and quenching rate on the internal microstructure, diffusion properties, and the strength of the interface between polycrystalline Cu and Cu–Ag barrier layers. The results showed that Cu40Ag60 and Cu60Ag40 present more than 95% of the amorphous at quenching rate between 0.25 and 25 K/ps, indicating a good glass-forming ability. Diffusion simulation showed that a better barrier performance can be achieved with higher amorphous ratio. For the sample of Cu20Ag80 with quenching rate of 25 K/ps, a void is initially generated in amorphous Cu–Ag layer during the tensile test. This indicates the strength of amorphous Cu–Ag is weaker than Cu–Ag/Cu interface and the polycrystalline Cu layer.

Preparation and characterization of Ni-Cu composite nanoparticles for conductive paints

Ni and Cu are the two most promising alternatives to noble metals used in electrical conductive materials. However, Cu is susceptible to oxidation, while Ni exhibits poorer electrical conductivity. To solve this problem, Cu-Ni composite nanoparticles have been prepared in the present work by successive hydrazine reduction based on the different oxidation potential between Cu (II) and Ni (II). The as-prepared products were characterized by XRD, FE-SEM, EDS, and TG, and the electrical resistivity of which was measured by four-probe method. A formation process of the composite particles was proposed and demonstrated. The Cu-Ni composite nanoparticles have a uniform diameter of about 50nm, and exhibit higher oxidation temperature than Cu and lower electrical resistivity than Ni. This novel Ni-Cu structure and method might help solve the problems associated with the oxidation of Cu and the low electrical conductivity of Ni, which would further promote the application of base metal conductive powders.

Influence of Ag on the Properties of Ca0.9Yb0.1MnO3 Sintered Ceramics

In this study, Ca0.9Yb0.1MnO3 + x wt.% Ag (with x = 0, 1, 3, 5, and 10) thermoelectric materials were prepared via the classical ceramic method. In spite of the very high sintering temperature (1300 °C), no significant Ag losses were observed following this process. Moreover, Ag addition enhanced cation mobility during sintering due to the formation of a liquid phase. Microstructurally, it was found that Ag decreases porosity; this was confirmed by density measurements. Ag was also found to promote the formation of a Ca2Mn2O5 secondary phase. Despite the presence of this secondary phase, samples with Ag displayed lower electrical resistivity than Ag-free ones, without a drastic decrease in the absolute Seebeck coefficient. The highest thermoelectric performances, which were determined by power factor, were obtained in 1 wt.% Ag samples. These maximum values are slightly higher than the best of those reported in the literature for sintered materials with similar compositions, with the additional advantage of their being obtained using a much shorter sintering procedure.

Preparation and Characterization of Sprayed-Yttrium Oxyfluoride Corrosion Protective Coating for Plasma Process Chambers

This study investigates the microstructure, mechanical and electrical properties of dense yttrium oxyfluoride (YOF) coatings fabricated by the atmospheric plasma spraying technique. Transmission electron microscopy and X-ray diffraction analysis revealed a well crystallized YOF coating with preferred orientations. The YOF coatings were more porous (approximate porosity 0.5%), with higher hardness (290 ± 30 HV), lower electrical resistivity (1016 Ω⋅cm), and breakdown voltage (5.57 kV), than conventional yttrium-fluoride plasma-protective coating. These results indicate the potential of the YOF coating as a novel antiplasma and corrosion-resistant ceramic.

Influence of an interlayer on thermoelectric power factor of HMS film on quartz substrate

The influence of an AlO x oxide or Si interlayer on the thermoelectric power factor of the higher manganese silicide (HMS, MnSi y, y = 1.73–1.75) film deposited on quartz substrate is investigated. The HMS film and the interlayer are prepared on quartz substrate by magnetron sputtering of MnSi 2, Al , Si and Si : B (1 at.% B content) targets. It is found that the metallic phase MnSi is present in the semiconducting HMS film without an interlayer, resulting in a lower Seebeck coefficient, 0.160 mV/K, but not a lower electrical resistivity, 0.021 Ω ⋅cm at 683 K. The thermoelectric power factor is only 122 × 10-6 W/mK2 at 683 K. On the other hand, the metallic phase MnSi disappears and the Seebeck coefficient restores to its high value after using the AlO x oxide or Si interlayer. Besides, the electrical resistivity decreases by using the AlO x oxide or Si : B interlayer. The HMS film with an Si : B interlayer has the highest Seebeck coefficient, 0.247 mV/K, and the lowest electrical resistivity, 0.011 Ω ⋅cm, at 683 K. Thus, the thermoelectric power factor is enhanced and can reach 555 × 10-6 W/mK2 at 683 K.

Preparation of (La,Sr)MnO3 Thin Film by Chemical Solution Deposition

Thin films of (La,Sr)MnO3 (LSMO) were fabricated by industrial-versatile chemical solution deposition (CSD) technique. Well [100]-oriented LSMO films were fabricated at 650-750 °C by use of buffer layers of LaNiO3 buffer layer on a silicon substrate. The product of lower electrical resistivity is promising as an electrode of fatigue-free ferroelectric capacitor.

PROPERTIES OF GLASS-LESS PHOTOIMAGEABLE PASTE FOR MULTILAYER LTCC STRUCTURES FABRICATION

Properties of Ag-based glass-less photoimageable paste designed for unfired LTCC were investigated. The paste isn't designed for patterns performing on the external surface of the substrate. Because it doesn't contains glass layer to substrate adhesion after the firing process is very weak. Also between individual grains of the silver there is no glass what could resulting in increased contact area of adjacent grains. It may improve the paste sintering. As a result lower electrical resistivity of the layer can be achieved. But also mechanical strength of the layer is reduced. In practice, the paste is not suitable for patterns fabrication on the external surface of the substrate - it detaches from it. The ink is designed for performing the buried layers inside LTCC ceramics. Investigations showed good compatibility of the paste and the DP951 and DP9K7 green tapes (DuPont). The tests showed designed pattern was precisely imaged on the substrate. Details had sharp, perpendicular edges what is characteristic for the photoimageable inks technique.

Thermoelectric Properties of Half-Heusler Compounds N-type MNiSn and P-type MPtSn (M = Hf, Zr)

To design and to develop Half-Heusler based high-temperature thermoelectric materials, thermoelectric properties of n-type MNiSn and p-type MPtSn (M = Hf, Zr) were investigated based on two respective strategies. For the n-type (Hf, Zr)NiSn, a combined process of optical floating zone melting and hot-pressing was applied aiming to reduce thermal conduction through the lattice contribution. For the p-type HfPtSn, power factor and hence figure of merit ZT were dramatically improved by the p-type doping of Ir and Co targeting for Pt-site, which effectively lower electrical resistivity. The additions of Ir and Co are expected not only to increase carrier concentration but also to suppress the lattice thermal conduction by substituting for Pt.