Plasma-Sprayed (Bi2O3)0.705 (Er2O3)0.245 (WO3)0.05 Electrolyte for Intermediate-Temperature Solid Oxide Fuel Cells (IT-SOFCs).

Stabilized bismuth oxide material with fluorite structure (δ-Bi2O3) has been studied as a promising electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs) due to its high oxygen ion conductivity in mediate temperature. Especially, the ternary system Bi2O3-Er2O3-WO3 is widely concerned for its high ionic conductivity and thermal stability. In this study, regarding its low melting point, the possibility to deposit dense Bi2O3-Er2O3-WO3 ((Bi2O3)0.705 (Er2O3)0.245 (WO3)0.05, EWSB) electrolyte by plasma spraying was examined. It was confirmed that the sintered EWSB bulk presents a high ion conductivity of 0.34 S cm-1 at 750 °C and excellent stability that indicates no structure transformation and conductivity degradation after annealing at 600 °C for 1000 h. The phase structure and cross-sectional microstructure of plasma-sprayed EWSB were characterized by XRD and SEM. Results showed that the as-plasma-sprayed EWSB presents a dense microstructure with well bonded lamellae. The XRD showed the formation of EWSB with δ-phase and a trace of ß-phase, while the ß-phase disappeared after annealing at 750 °C for 10 h. The deposited EWSB electrolyte presented the excellent ionic conductivity of 0.26 S cm-1 at 750 °C which can be directly applied to SOFC at intermediate temperature.

Recent Research Advances in Plasma Spraying of Bulk-Like Dense Metal Coatings with Metallurgically Bonded Lamellae.

Although thermal spray metallic coatings have been widely used for materials protection from wear, corrosion and oxidation, its porous feature limits the full utilization of materials potential. Moreover, the oxidation inherent to thermal spraying in the ambient atmosphere is detrimental to interlamellar bonding formation, which further degrades the performance of thermal spray metal coatings. How to tape out the full potential of spray materials in the form of the coating is a still great challenge to thermal spray coating technology. Facing such challenge, recent efforts have been made to deposit dense metallic coatings with sufficiently bonded lamellae by oxide-free molten droplets through atmospheric plasma spraying. In this paper, the strategies for depositing bulk-like metal coatings will be reviewed. The formation of the bulk-like coating through post-spray treatments is briefly reviewed including post-spray heat treatment and laser remelting following the brief introduction to the features of thermal spray metallic coatings. The effect of the substrate preheating temperature on the splat formation and subsequently the adhesion formation was examined to reveal the dominant limitation of resultant oxide scale. Then, the role of the deposition temperature on the formation of bulk-like metal deposits with neglecting the effect of oxidation during spraying by vacuum plasma spraying practices is shortly presented. The recent progress on the new strategies to develop spread-fusing bonding mechanism and in-situ in-flight deoxidizing mechanism through developing ultra-hot metallic droplets will be introduced. The thermodynamics and kinetics requirements for the in-situ in-flight deoxidizing through deoxidizer elements adding to alloy spray powders for achieving oxide-free molten droplets in the ambient atmosphere are examined. The conditions to develop the spread-fusing mechanism during the spreading of impacting molten metal droplet for metallurgical bonding are presented. It is obvious from this review paper that the realization of two mechanisms depends on both the spray materials design and heating control of in-flight particles. Through the generation of ultra-hot droplets by plasma spraying to achieve oxide-free molten droplets, strategically it will be possible to deposit bulk-like dense metallic coating through spread-fusing of splat surfaces with limited post-spray oxidation. Such strategies will tape out the full potential of coating materials and open up the new application fields for plasma spraying.

Microstructure and Ablation Behavior of Low-Pressure Plasma Sprayed ZrB2 Coatings Down to 100 Pa.

The effect of chamber pressure on the microstructure and ablation behavior of ZrB2 coatings deposited by low-pressure plasma spraying was investigated. The results showed that as the spray chamber pressure further was reduced to less than 50 kPa, the porosity of the coating deposited at the same distance decreased with the chamber pressure, and the coating prepared under 100 Pa presented the lowest porosity of about 0.89%. The ablation performance test subjected to high-temperature plasma jet revealed that the linear ablation rate of ZrB2 coating increased with the porosity of the coating. As a result, among the ZrB2 coatings deposited at chamber pressures of 100 Pa, 5 kPa, 10 kPa and 50 kPa, the dense coating deposited at 100 Pa showed the lowest ablation rate of 0.33 µm/s. The dense ZrB2 coating with a thickness of about 100 µm was able to withstand 300 s ablation by a plasma flame with a net power of 25 kW resulting in an ablating coating surface temperature of about 2000 °C. The ablation mechanism of the coating was also examined.

Synthesis of Si-Based High-Efficiency and High-Durability Superhydrophilic-Underwater Superoleophobic Membrane of Oil-Water Separation.

Oil pollution is caused by the frequent discharge of contaminated industrial wastewater and accidental oil spills and is a severe environmental and health concern. Therefore, efficient materials and processes for effective oil-water separation are being developed. Herein, SiO2-Na2SiO3-coated stainless steel fibers (SSF) with underwater superoleophobic and low-adhesion properties were successfully prepared via a one-step hydrothermal process. The modified surfaces were characterized with scanning electron microscopy (SEM), and contact angle measurements to observe the surface morphology, confirm the successful incorporation of SiO2, and evaluate the wettability, as well as with X-ray diffraction (XRD). The results revealed that SiO2 nanoparticles were successfully grown on the stainless-steel fiber surface through the facile hydrothermal synthesis, and the formation of sodium silicate was detected with XRD. The SiO2-Na2SiO3-coated SSF surface exhibited superior underwater superoleophobic properties (153-162°), super-hydrophilicity and high separation efficiency for dichloromethane-water, n-hexane-water, tetrachloromethane-water, paroline-water, and hexadecane-water mixtures. In addition, the as-prepared SiO2-Na2SiO3-coated SSF demonstrated superior wear resistance, long-term stability, and re-usability. We suggest that the improved durability may be due to the presence of sodium silicate that enhanced the membrane strength. The SiO2-Na2SiO3-coated SSF also exhibited desirable corrosion resistance in salty and acidic environments; however, further optimization is needed for their use in basic media. The current study presents a novel approach to fabricate high-performance oil-water separation membranes.

Fabrication of Nanostructured Cadmium Selenide Thin Films for Optoelectronics Applications.

There is lot of research work at enhancing the performance of energy conversion and energy storage devices such as solar cells, supercapacitors, and batteries. In this regard, the low bandgap and a high absorption coefficient of CdSe thin films in the visible region, as well as, the low electrical resistivity make them ideal for the next generation of chalcogenide-based photovoltaic and electrochemical energy storage devices. Here, we present the properties of CdSe thin films synthesized at temperatures (below 100°C using readily available precursors) that are reproducible, efficient and economical. The samples were characterized using XRD, FTIR, RBS, UV-vis spectroscopy. Annealed samples showed crystalline cubic structure along (111) preferential direction with the grain size of the nanostructures increasing from 2.23 to 4.13 nm with increasing annealing temperatures. The optical properties of the samples indicate a small shift in the bandgap energy, from 2.20 to 2.12 eV with a decreasing deposition temperature. The band gap is suitably located in the visible solar energy region, which make these CdSe thin films ideal for solar energy harvesting. It also has potential to be used in electrochemical energy storage applications.

Plasma-Sprayed High-Performance (Bi2O3)0.75(Y2O3)0.25 Electrolyte for Intermediate-Temperature Solid Oxide Fuel Cells (IT-SOFCs).

Rare earth element-doped bismuth oxides with the fluorite structure (δ-Bi2O3) exhibit high oxygen ion conductivity at low temperature, which is promising electrolyte materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). However, traditional co-sintering process is not applicable to the manufacturing of IT-SOFCs using low melting point Bi2O3-based electrolyte, while further high-temperature processing is not required for deposition Bi2O3-based electrolytes. In this study, plasma spraying was used to examine the possibility to deposit high-performance Bi2O3-based electrolytes without the following high-temperature process. (Bi2O3)0.75 (Y2O3)0.25 (YSB) spray powders were prepared by the sinter-crushing method. The YSB electrolytes were fabricated by plasma spraying at different deposition temperatures. The effects of deposition temperature on the coating microstructure, crystalline stability, and ion conductivity were investigated. Results showed that the as-sprayed YSB electrolytes present a dense microstructure with well-bonded lamellar interfaces. The pure δ-phase YSB electrolyte was deposited with 37.5-75 µm powders at a deposition temperature of 350 °C. The deposited YSB electrolyte presented the excellent ionic conductivity of 0.19 S cm-1 at 700 °C in comparison with 0.21 S cm-1 for sintered bulk.

Effect of Powder Particle Size and Spray Parameters on the Ni/Al Reaction During Plasma Spraying of Ni-Al Composite Powders.

It was known for long that Ni-Al composite powders can be used to deposit self-bonding coating as a bond coat for common ceramic coatings due to the exothermic reaction between Ni and Al. However, it was found that with commercial Ni-Al composite powders with a large particle size, it is difficult to ignite the self-propagating reaction between Ni and Al to form Ni-Al intermetallics by plasma spraying. In this study, Ni-Al composite powder particles of different sizes were used to prepare Ni-Al intermetallics-based coatings by plasma spraying. The dependencies of the exothermic reaction between Ni and Al and the coating microstructure on powder particle size and spray parameters were investigated. The phase composition, microstructure, porosity and oxide content of the coatings were characterized by x-ray diffraction, scanning electron microscope and image analyzing. The results show that particle size of Ni-Al composite powders is the dominant factor controlling the exothermic reaction for the formation of Ni-Al intermetallics during plasma spraying. When the powders larger than about 50 µm are used, the reaction forming aluminide cannot complete even by heating of plasma flame generated at high plasma arc power. However, when smaller powders less than 50 µm are used, the exothermic reaction can completely occur rapidly in plasma spraying, contributing to heating of Ni-Al droplets to the highest temperature for development of the self-bonding effect. The positive relationship between molten droplet temperature and tensile adhesive strength of the resultant coatings is recognized to confirm the contribution of high droplet temperature to the adhesive or cohesive strength.

MicroRNA-155 deficiency attenuates inflammation and oxidative stress in experimental autoimmune prostatitis in a TLR4-dependent manner.

To explore the mechanism of microRNA-155 (miR-155) deficiency, protecting against experimental autoimmune prostatitis (EAP) in a toll-like receptor 4 (TLR4)-dependent manner. After wild-type (WT) and miR-155-/- mice were injected with complete Freund's adjuvant and prostate antigen to establish EAP model, half were randomly selected for injection with lipopolysaccharide (LPS, a TLR4 ligand). The following experiments were then performed: von Frey filaments, hematoxylin-eosin (HE) staining, real time quantitative polymerase chain reaction (qRT-PCR), Western blotting, and enzyme-linked immunosorbent assay (ELISA). And the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and the level of Malondialdehyde (MDA) were detected by corresponding kits.miR-155-/- mice with prostatitis exhibited the attenuated pelvic tactile allodynia/hyperalgesia and the suppressed TLR4/nuclear factor-kappa B (NF-κB) pathway as compared with the WT mice with prostatitis. In addition, LPS enhanced the upregulation of miR-155 and the activation of the TLR4/NF-κB pathway in the prostatic tissues of WT mice with EAP. Furthermore, prostatitis mice had aggravated inflammation scores accompanying the increased interleukin (IL)-1ß, tumor necrosis factor-α, IL-6, interferon-γ, IL-12, and MDA in prostatic tissues with the decreased IL-10, SOD and GSH-Px, and the unaltered IL-4. Compared with the mice from the WT + EAP group and the miR-155-/- + EAP + LPS group, mice from the miR-155-/- + EAP group had decreased inflammation and oxidative stress. miR-155 deficiency ameliorated pelvic tactile allodynia/hyperalgesia in EAP mice and improved inflammation and oxidative stress in prostatic tissues in a TLR4-dependent manner involving NF-κB activation, thereby exerting a therapeutic effect in chronic prostatitis treatment.

Bioinspired Mechanically Robust Metal-Based Water Repellent Surface Enabled by Scalable Construction of a Flexible Coral-Reef-Like Architecture.

Mechanical robustness is a central concern for moving artificial superhydrophobic surfaces to application practices. It is believed that bulk hydrophilic materials cannot be use to construct micro/nanoarchitectures for superhydrophobicity since abrasion-induced exposure of hydrophilic surfaces leads to remarkable degradation of water repellency. To address this challenge, the robust mechanical durability of a superhydrophobic surface with metal (hydrophilic) textures, through scalable construction of a flexible coral-reef-like hierarchical architecture on various substrates including metals, glasses, and ceramics, is demonstrated. Discontinuous coral-reef-like Cu architecture is built by solid-state spraying commercial electrolytic Cu particles (15-65 µm) at supersonic particle velocities. Subsequent flame oxidation is applied to introduce a porous hard surface oxide layer. Owing to the unique combination of the flexible coral-reef-like architecture and self-similar manner of the fluorinated hard oxide surface layer, the coating surface retains its water repellency with an extremely low roll-off angle (<2°) after cyclic sand-paper abrasion, mechanical bending, sand-grit erosion, knife-scratching, and heavy loading of simulated acid rain droplets. Strong adhesion to glass, ceramics, and metals up to 34 MPa can be achieved without using adhesive. The results show that the present superhydrophobic coating can have wide outdoor applications for self-cleaning and corrosion protection of metal parts.

MD Simulation on Collision Behavior Between Nano-Scale TiO2 Particles During Vacuum Cold Spraying.

Particle collision behavior influences significantly inter-nano particle bonding formation during the nano-ceramic coating deposition by vacuum cold spraying (or aerosol deposition method). In order to illuminate the collision behavior between nano-scale ceramic particles, molecular dynamic simulation was applied to explore impact process between nano-scale TiO2 particles through controlling impact velocities. Results show that the recoil efficiency of the nano-scale TiO2 particle is decreased with the increase of the impact velocity. Nano-scale TiO2 particle exhibits localized plastic deformation during collision at low velocities, while it is intensively deformed by collision at high velocities. This intensive deformation promotes the nano-particle adhesion rather than rebounding off. A relationship between the adhesion energy and the rebound energy is established for the bonding formation of the nano-scale TiO2 particle. The adhesion energy required to the bonding formation between nano-scale ceramic particles can be produced by high velocity collision.

Small molecule-driven directional movement enabling pin-hole free perovskite film via fast solution engineering.

Organolead trihalide perovskite materials have been widely used as light absorbers in efficient photovoltaic cells. Solution engineering is a fast and effective method to fabricate perovskite films. Here, we report a fast precipitation of a pin-hole free perovskite film by small molecule-driven directed diffusion engineering. Solvent molecules diffuse easily and quickly by colliding with small molecules, e.g. helium. Fully compact perovskite films and highly efficient perovskite solar cells are achieved, and the devices show remarkable stability of ca. 90% original efficiency after more than 1000 hours of testing. The small molecule driving directed diffusion offers a promising fast precipitation of a perovskite film and highly efficient, stable perovskite solar cells.

Ultra-high open-circuit voltage of perovskite solar cells induced by nucleation thermodynamics on rough substrates.

To obtain high performance CH3NH3PbI3 perovskite solar cells, it is highly important to realise a high open-circuit voltage. Calculation results based on a modified diode model have indicated that a low bare ratio ϕ of the perovskite film is the most important factor determining the open-circuit voltage, where ϕ is defined as the ratio of the projection of the uncovered area of the perovskite film to the apparent area of the total substrate surface. To realise a low ϕ, we investigate the nucleation behaviour of crystals on rough substrates. The analysis results predict that, when CH3NH3PbI3 is deposited on conventional transparent conductive oxide substrates such as fluorine-doped tin oxide, preferential heterogeneous nucleation will occur on the concave regions of the substrate; then, depending on the subsequent growth step, full coverage of the perovskite film at both the macroscopic and microscopic scales is realised. As a result, an ultra-high open-circuit voltage, i.e., 1.20 V, can be achieved in devices using the full coverage CH3NH3PbI3 film. The thermodynamics theory of precipitation nucleation should shed light on solution engineering of thin films.

Nano-porous TiO2 layer using ultrafine nano-particles for the blocking layer in dye-sensitized solar cells.

A nano-porous TiO2 layer was produced by spray-deposition using ultrafine anatase nano-particles for the blocking layer for the dye-sensitized solar cells (DSCs). The microstructure and the electrochemical properties of the spray-deposited TiO2 layer were examined. The results of electrochemical properties showed that the spray-deposited TiO2 layer was capable to suppress the I3- ions diffusion to FTO substrate, reducing the electron recombination between the electrons on FTO substrate and I3- ions in electrolyte. In addition, the connection between TiO2 film and FTO substrate was improved by the TiO2 layer. Therefore, the short circuit current density and thereby the photo-to-electric energy conversion efficiency were improved by this blocking layer. The blocking effect of the porous layer was attributed to both the complicated pore structure of the spray-deposited layer and the enhanced connections between TiO2 film and FTO substrate. The low temperature characteristic of spray deposition approach indicates that it is suitable to the flexible-based DSCs.