Nanostructured Hybrid Metal Mesh as Transparent Conducting Electrodes: Selection Criteria Verification in Perovskite Solar Cells

Nanostructured metal mesh structures demonstrating excellent conductivity and high transparency are one of the promising transparent conducting electrode (TCE) alternatives for indium tin oxide (ITO). Often, these metal nanostructures are to be employed as hybrids along with a conducting filler layer to collect charge carriers from the network voids and to minimize current and voltage losses. The influence of filler layers on dictating the extent of such ohmic loss is complex. Here, we used a general numerical model to correlate the sheet resistance of the filler, lateral charge transport distance in network voids, metal mesh line width and ohmic losses in optoelectronic devices. To verify this correlation, we prepared gold or copper network electrodes with different line widths and different filler layers, and applied them as TCEs in perovskite solar cells. We show that the photovoltaic parameters scale with the hybrid metal network TCE properties and an Au-network or Cu-network with aluminum-doped zinc oxide (AZO) filler can replace ITO very well, validating our theoretical predictions. Thus, the proposed model could be employed to select an appropriate filler layer for a specific metal mesh electrode geometry and dimensions to overcome the possible ohmic losses in optoelectronic devices.

Hydrologic and Pollutant Removal Performance of Media Layers in Bioretention

The current study was aimed to investigate the filler layer structure in modified bioretention systems. Three different structural layers in bioretention were proposed to evaluate their hydrologic performance and pollutant removal efficiency under different rainfall intensities. These layers were as follows: all three layers (filter, transition, and drainage layers), without transition layer, and without drainage layer. Synthetic stormwater was used for experimental purpose in current work. Results revealed that compared with “all three layers”, runoff control rate of “without transition layer” and “without drainage layer” was reduced by 0 to 7.4%, 0 to 10.1%, and outflow start time was advanced by 6 to 8 min and 1.5 to 4.5 min, respectively. Moreover, CODcr (chemical oxygen demand), NH4+-N (ammonium nitrogen), TN (total nitrogen) and TP (total phosphorus) removal rates were 86.0%, 85.4%, 71.8%, and 68.0%, respectively. Particle size distribution of the fillers revealed that during operation, particle moved downward were mainly within 0.16–0.63 mm size. Findings showed that transition and drainage layer played an important role in runoff control, and total height of the filler layer should not be less than 800 mm. Filter layer effectively reduce runoff pollution but the thickness of the filter layer should not be less than 500 mm. Whereas, transition layer has the function of preventing the filler loss of the filter layer; therefore, proper measures must be taken into consideration during structural optimization.

Adaptive Structure Design of Raingarden in Shanghai Coastal Saline Alkali Area for Improving Urban Resilience

<p>Shanghai is one of the demonstration sites of Sponge City which is a typical coastal saline-alkali area. To improve the urban resilience and mitigate storm water, green infrastructure as raingarden, bioswale and green roof, etc. are used to regulate runoff. However, the design of raingarden have the disadvantage of solutions for high groundwater levels and soil salinization in Shanghai. In order to improve the regional adaptability and optimize the design of the raingarden, the indoor rainfall simulation experiments and orthogonal experiments were used to analyze the effect of salt isolation and rain infiltration impacted by different structures (salt-insulated layer material, salt-insulated layer position, filler layer thickness). The results show that the order of influence on salt isolation is: salt-insulated material>filler layer thickness>salt-insulated layer position. The order of impact on rain infiltration is: salt-insulated material>salt-insulated layer location>filler layer thickness. Three types of rain garden structures are proposed. The first is strong salt-insulated rain garden suitable for severe saline-alkali areas. The second is suitable for the comprehensive rain garden in the moderate saline-alkali area. The third is suitable for the permeable rain garden in the light saline-alkali area.</p>

Influence of the Mg and Bi content on brazeability of MONOBRAZE material under flux-free brazing conditions

In the conventional brazing, the clad materials with the filler layer and the flux coating have been used to get good brazeability. However, an innovative Al-Si based single-layer brazing material (MONOBRAZE® material) has been developed recently which does not need filler layer by supplying molten filler from the inside of the material during brazing. In addition, a new flux-free brazing technique has also been developed. In the flux-free brazing, Mg and Bi are added to break the oxide film and to improve the wettability of molten filler, respectively. However, it is not clarified how these element works on the brazeability of MONOBRAZE® material in flux-free brazing. Therefore, in this study the effect of Mg and Bi content on the brazeability of MONOBRAZE® material was investigated. From the result, it is found that MONOBRAZE® material is applicable for flux-free brazing by adding Mg. Mg is considered to break the oxide film into fine particles and Bi is considered to assist the destruction of oxide film. From this cause, a new aluminum substrate surface was exposed which allow molten filler to move on the surface and contribute to the formation of the fillet.

Innovative Research in the Field of Brazed Joints for Drill Bit

The research followed the development of deep joint brazing joints with economic efficient materials between the reinforcement, made from sintered wolfram carbide, and the support, drill bit made from low alloy steel with chromium, from the earthmoving equipment. The brazing procedure selected is heating until the semi-products of the addition materials reach melting temperature, with oxyacetylene flame slightly carburized. The pressure of reducing manufacturing costs for drill bits highlighted the need to replace brazing alloys Ag156 according to SR EN ISO 17672 with coated rods type VIAg140R, which are less expensive and successively deposit two layers in one melt, one buffer layer and a filler layer. The buffer layer has a high moistening capacity of sintered wolfram carbides; it contains Ag156 that comes from the coat of the covered rods, in which it participates with up to 10%. The filler layer of the brazed joint is made out of Ag140. The global chemical composition of the deposited metal with VIAg140R complies with prescriptions SR EN ISO 17672 for Ag140. Metallographic analysis and sclerometric tries of specific area of the brazed joints did not highlight any embrittlement imperfections, which lead to the possibility of suggesting the new technology for brazing and extending it to a large number of similar joints

Laser Brazing of Diamond Grits with a Ni-Based Brazing Alloy

Brazing diamond grits onto steel substrate using a Ni-based filler alloy was carried out by laser beam in an argon atmosphere. The microstructure of the interfacial region among the Diamond grits, the filler layer and the steel substrate, were investigated by means of scanning electron microscopes (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). Meanwhile, the formation mechanism of carbide layers was discussed. All the results indicated that the active element chromium in the Ni-based alloy concentrated preferentially to the surface of the grits to form a chromium-rich layer, and the hard joint between the alloy and the steel substrate is established through a cross-diffusion of iron and Ni-based alloy.

Effect of Nanoscale SiC Particles on Strength Distribution of Joined Si3N4 to Inconel Alloy

Two-layered Si3N4/SiC nano-composites with 50vol.% SiC have been fabricated by two-step sintering of a powder mixture of a-Si3N4 and carbon powder with a mean size of 13nm, and 5wt.% Y2O3. Nano-sized SiC particles were formed through reactions: carbon and surface SiO2 on the Si3N4 particles, and carbon and Si3N4 particles. To combine the specific advantages of nanoscale ceramics with that of metals, they are often used together within one composite component. In this study, the fabrication and mechanical properties of a nanoscale SiC layer brazed with an Inconel alloy were investigated. It was shown that, with a variation of strain rate, the joints have a bending strength of 330-380MPa, and the deflection of the interlayer increases with increasing strain rate. The fracture types are classified into three groups; cracks grow into the metal-brazing filler layer, the ceramicbrazing filler layer or inside the ceramic.