What’s new in laser based nanofabrication for the fast uptake in industrial application

Laser based efficient new nanofabrication methods with technical feasibility for the fast uptake in industrial application are of significant global demand. A recent simplest approach in this way is the standard pulsed laser deposition (PLD), used since 1960s after the development of high power lasers. Over all, PLD is a fit method towards the preparation of a variety of nanomaterials only for research purpose. Nevertheless, the method is relatively slow and could not adopted in industrial scale application. A recent new-fangled development in this direction is the atmospheric-PLD (APLD), where ablation of the target by a laser pulse occurs at atmospheric gas pressure and the ablated material is delivered to the substrate using a flowing medium such as gas or atmospheric plasma. With this method, a variety of nanomaterials such as plasmonic metal NP film could be produced for practical ap

Catalytic performance of Ce1-xLnxOy of nanocrystalline Ln (III-IV)-substituted ceria

The activity of several lanthanide promoted Ceria in CO oxidation was studied. Samples were obtained by a high yield and sustainable method by urea thermal decomposition. Precursors basic carbonates, Ce1-xLnx(OH)CO3, being Ln = La (III), Sm(III), Gd(III), Pr(III) were prepared in the range of compositions 0 to 30 at.%. These precursors were annealed to moderate temperature obtain Ln-Ce mixed oxides, at 450ºC. These exhibit large surface areas up to 120 m2/g. Their catalytic performance revealed good activity towards CO oxidation (COOX) for all samples. However, a different behavior may be observed for Ln content higher than 20 at.%. By the reactor operation in differential conditions, the activation energy for COOX were obtained for all samples. The rise of activation energy as a function of Ln(III-IV) content is analyzed in the frame of phase stability and surface segregation.

Optimization of laser cladding process for additive repair of high temperature and high pressure valve sealing surface

Laser cladding technology is highly suitable for the remanufacturing of thin-walled and easily deformable parts due to its concentrated energy density. Due to the high temperature and high pressure corrosion environment, the valve sealing surface is prone to corrosion, wear and other failures. A nickel-based tungsten carbide alloy layer was prepared on the valve sealing surface substrate material by laser cladding process. By designing orthogonal experiments, the effects of laser power (P), scanning speed (Vb), powder feeding rate (Vf), and WC content (wt%) on the alloy layer were investigated. A fuzzy comprehensive evaluation method including macroscopic quality, microstructure, microhardness, anti-wear performance, oxidation resistance, compactness and corrosion resistance was proposed. The experimental results showed that the hardness, oxidation resistance and corrosion resistance of the laser alloy layer are significantly improved compared with the matrix; the optimum process parameters and the addition ratio of WC powder are laser power (P) of 1.1 kW and scanning speed (Vb) of 800 mm/min. The powder feeding rate (Vf) was 20%, and the WC content was 20% by weight.

Preparation and Characterization of Green Epoxy Resin Composites and Its Use in Corrosion Resistance

In this work, appropriate alternative for diglycidyl ether bisphenol A (DGEBA) was found to avoid the destructive effects of bisphenol A. Lignin, an aromatic compound from palm tree leaves, was used as a renewable material to synthesize a bio-based epoxy resin. Lignin extracted using Kraft pulping process. Kraft Lignin was epoxidized with epichlorohydrin in alkaline medium. Nano-titanium dioxide was used as filler with ratio of 10% to prepare the green epoxy composite. The structure of the Kraft lignin and lignin-based epoxy resin was proven via Infrared spectra (FT-IR) were recorded using solid KBr disk by testing Shimadzu (FT-IR-8300) spectrophotometer. The thermal properties of the curing process of lignin-based epoxy resin and composite were investigate using Differential scanning calorimetry (DSC) analysis. Potentiodynamic measurements data revealed that the anti-corrosion performance of the lignin based epoxy resin. The study demonstrates successful of epoxidation of Kraft lignin. In addition, lignin based eopxy resin showed effective inhibitor for carbon steel in 3.5 wt. % NaCl electrolyte solutions

Assessment of the Effect of Hydrolysed Starch Graft Copolymers Application on Soil Nutrient (Phosphorus and Nitrogen) Retention

The effects of the application of the graft copolymers (Hydrolyzed starch-g-polyacrylonitrile (HSPAN) and Hydrolyzed starch-g-polyacrylic acid (HSPAA)) on the nitrogen (N) and phosphorus (P) retention capacity of soil was evaluated in this study. Soil nutrient (N and P) retention capacity tests was carried out at three graft copolymers application rates (3.0, 6.0, and 9.0g/kg soil) against a blank soil sample to which graft copolymers was not applied. Diammonium phosphate (DAP) at 0, 100, and 200mg in aqueous solution/kg soil were applied in triplicates. The soil samples were mixed thoroughly and allowed to air-dry. The residual N and P contents of the soil samples were determined and reported as the amounts of nutrients retained as a function of the graft copolymer and DAP application rates. The result of this study has clearly demonstrated the potential of the graft copolymers to alleviate problems related to nutrient loss from the soil media. Leaching of nutrients (N and P) in soil has been found to be reduced to minimal (0.46%N, and 1.13%P) with the application of hydrolyzed graft copolymer and the nutrients are thus available to plant for growth by suction pressure difference.

Behavior of Cast {TI OR TA}-Containing Alloys Based on Nickel and/or Cobalt in High Temperature Oxidation:Effect of the NI/ CO Ratio

Many of the cast superalloys chosen for specific applications at high temperatures, such as tools devoted for shaping molten glass, are based on nickel or cobalt. They contain chromium and carbon to achieve good resistances against both mechanical stresses and hot oxidation/corrosion, by favoring the formation of reinforcing carbides at solidification and the development of a protective oxide scale of chromia during service. In presence of tantalum or titanium in the chemical composition of the alloys, high performance MC carbides may be obtained but this depends on the base element. One recently observed how the respective proportions of nickel, cobalt and chromium may promote the formation of TiC or TaC at the expense of chromium carbides. The ratings chosen for No, Co and Cr may have high influence on the oxidation of the alloys at high temperature this is what was studied in this work.

Quasi-particle Contribution in Thermal Expansion and Thermal Conductivity in Metals

In this paper the modified Landau theory of Fermi Liquids was used to compute the thermal expansion and thermal conductivity of quasi-particles in metals. The result revealed that as temperature increases the thermal expansion of quasi-particles in metals increases in all the metals investigated. It is also observed that as the electron density parameter increases the thermal expansion of quasi-particles increases. This shows that at low density region the thermal expansion of quasi-particles is large. The result obtained for the thermal conductivity of quasi-particles in metals revealed that for all the metals computed the thermal conductivity of quasi-particles decreases as temperature increases. This seems to suggest that as temperature increases the separation between quasi-particles increases because they are not heavy particles hence, the rate of absorbing heat decreases. The computed thermal expansion and thermal conductivity of quasi-particles are in better agreement with experimental values. This suggests that the introduction of the electron density parameter is promising in predicting the contribution of quasi-particles to the bulk properties of metals. This study revealed the extent to which quasi-particles contribute to the bulk properties of metals, which assisted their potential applications in materials science and engineering development.

Efficient NO Photodegradation of Hydrothermally Synthesized TiO2 Nanotubes under Visible Light

In this study, TiO2 nanotubes (TNTs) were synthesized via a hydrothermal process and characterized by high-resolution transmission electron microscopy (HR-TEM) images, selected area electron diffraction (SAED) pattern, and photoluminescence (PL) analysis. The NO removal photocatalytic activity of the hydrothermally synthesizedTNTs was surveyed systematically. The hydrothermally synthesizedTNTs have shown an efficient NO photodegradation which is approximately 4 times higher than that of P25 and an excellent photostability under visible light after 5 cycles. Furthermore, reactive radicals mainly involved in the photocatalytic reaction were identified by electron spin resonance (ESR) study, leading to a better understanding of the photocatalytic mechanism of the hydrothermally synthesized TNTs.

Comparison of the antibacterial activity against Escherichia coli of silver nanoparticle produced by chemical synthesis with biosynthesis

The synthesis of silver nanoparticles (Ag NPs) has been carried out using different methods, mainly by biological and chemical methods; however, comparing antibacterial activity of Ag NPs synthesized by these methods has not been conducted before. In this study, silver nanoparticles (Ag NPs) were synthesized by methods using reducing agent NaBH4/carboxymethyl cellulose (CMC) and fungal strain Trichoderma asperellum (T.asperellum). The formation of silver nanoparticles was observed visually by color change and identified by Ultraviolet-visible (UV – vis) spectroscopy. The transmission electron microscopy (TEM) image illustrated almost nanoparticles with spherical shape and average diameter of 4.1 ± 0.2 nm and 2.1 ± 0.2 nm of samples produced from chemical reduction and biosynthesis respectively. Both samples after 180 days storing have been separated lightly, but the agglomeration and absorbance peak shifting were not observed which proved the high stability of synthesized Ag NPs. Antimicrobial activity against human bacterial pathogen Escherichia coli (E. coli) showed that the inhibition zone produced by “biosynthesis” and “chemical reduction” Ag NPs were 3.17 cm and 2.42 cm respectively. With nanoparticles size smaller than 2 mm, antibacterial activity of “biosynthesis” Ag NPs against E. coli was 31 % higher than “chemical reduction” Ag NPs, although the concentration of Ag NPs produced by biosynthesis was about 10-fold less.

The development of polyurethane

Polyurethane is one of the six promising synthetic materials in the world. Due to its excellent product performanceand wide application field, it is a crucial industry of development in the world. This paper introduces the progressof polyurethane industry in recent years which includes polyurethane raw materials, classification and applicationprospects. The research methods and principles of waterborne polyurethane were mainly studied. At the same time, thedevelopment of new polyurethane materials was held forward.