Papers by Keyword: Surface Coating

Abstract: The migration of lithium (Li) ions in electrode materials affects the rate performance of rechargeable Li ion batteries. Therefore, the application of LiMn₂O_4, which is an appealing cathode material in high power systems, requires fast electron transfer kinetics which is possible through the use of nanostructured morphologies and conductive material. Nanowires offer the advantage of a large surface to volume ratio, efficient electron conducting pathways and facile strain relaxation. In this study, LiMn₂O₄ nanowires with cubic spinel structure were synthesized by using a α-MnO₂ nanowire-template-based method. LiMn₂O₄ nanowires have diameters less than 10 nm and lengths of several micrometers. Fe-Au nanoparticles were synthesized and used as coating material to improve both the catalytic activities and stability of the LiMn₂O₄ nanowires. The Li[Fe_0.02Au_0.01]Mn_1.97O₄ nanowires with modified architecture effectively accommodates the structural transformation during Li⁺ ion charge and discharge. Hence, the Li[Fe_0.02Au_0.01]Mn_1.97O₄ nanowire cathode system shows outstanding stability and enhanced electrocatalytical properties. Microstructural analysis of Li[Fe_0.02Au_0.01]Mn_1.97O₄ linked its composition and processing to its properties and performance. High resolution transmission electron microscope (HR-TEM) of the nanomaterial showed good crystallinity which contributed towards good reversibility. XRD analysis revealed a pure cubic spinel structure without any impurities. Structural information provided by Raman and solid state spectroscopy further corroborated these findings. The improved rate and cycling performance is related to the conductive particles infused within the nanowires which make up the electrode.

Abstract: This study deals with TiO₂ coating of powder Mn-Zn ferrite in order to recieve photocatalytic layer on the top of these particles, forming core-shell catalyst. Powder catalysts are of great advance over the world due to the high surface area, considering the kinetics proceeds through heterogenous phase boundary catalysis. However their withdrawal from cleaning systems often requires energetically and economically demanding processes such as filtration and ultrafiltration. Since the ferrite is magnetic, the advantage of such formed core-shell photocatalyst is easibility of removing from photocatalytic decomposition system using external magnetic field. In this study the surface coating is performed, using Ti alkoxides mixtures with nanosized TiO₂ particles and C and Au coating to form film layer of TiO₂ on the surface of ferrite. XRD, SEM – EDS analyses are employed to study surface coating.

Abstract: Surface coating is sharing the responsibility between coating and substrate, which enhances the surface properties such as strength, hot hardness and toughness, wear resistance, antifriction and chemical inertness. The present work is focused on wear behavior of Mild Steel substrate material deposited with Titanium dioxide-30 wt % of Inconel718 incorporating plasma spray process. These composite coatings were subjected to slurry erosion wear test by simulating the corrosive-erosive atmosphere by mixing of silica sand and 3.5 percent of NaCl in distilled water. Under identical conditions, coated mild steels gave better wear resistance compared to uncoated sample.

Abstract: Surface protection by hydrophobic impregnation and surface coating are widely used for concrete bridges located at coastal area in Japan. This paper deals with the improvement of adhesion between surface coating and hydrophobic impregnated concrete by different types of silanes and by invastigating surface treatment methods. As a result, adhesion between hydrophobic impregnated concrete and epoxy-based surface coating were improved by applying abrasive paper, portable electric grinder, solvent or diluted hydrochloric acid treatment. Especially, using portable electric grinder gave a remarkable improvement to the adhesive property. Also, hybrid-surface protection system consisting of surface coating and hydrophobic impregnation was discussed to prevent blistering.

Abstract: This study deals with stability and quality of surface treatment of concrete roof tiles, considering the use of special inorganic binders spraying onto freshly prefabricated surface of concrete roof tiles. Their application leads to smoothing of surface defects generated from previous processing. Method of applying the coating is discussed in this work among with stability study of styrene-acrylate cement mixtures. Impact of presence of selected styrene-acrylate copolymer onto the hydration of cement is evaluated, in order to verify, for how long could be prepared mixture used for treating freshly fabricated surface of concrete roof tiles. Pull-off tests results after freeze-thaw test are further presented in this study to verify designed coating process properties.

Abstract: LiNi_0.8Co_0.15Al_0.05O₂, as the cathode materials for lithium ion battery, were prepared from the precursors, Ni_0.8Co_0.15Al_0.05(OH)₂ which were synthesized by chemical co-precipitation method. LiNi_0.8Co_0.15Al_0.05O₂ particles are modified with AlF₃ and AlPO₄. Even though the initial discharge capacity of the coated LiNi_0.8Co_0.15Al_0.05O₂ was decreased that of the pristine material, the capacity retention and the thermal stability, in a highly oxidized state are both significantly improved. This effect is attributed to the thin coating layer protecting the oxidized cathode particles from being attacked by hydrogen fluoride in the electrolyte. The cycling behavior of the AlF₃-coated LiNi_0.8Co_0.15Al_0.05O₂ is quite stable showing good capacity retention (96.3% of its initial capacity after 30 cycles).

Abstract: The complex permittivity and permeability of Dravite, Elbaite, ZnO and Dravite/ZnO complex powder are analyzed in this paper. Within the frequency range of 2~18 GHz, the dielectric losses of these four materials are in the sequence of: 0 ≈ Dravite ≈Elbaite < ZnO < coated powder = 0.211. The complex powder's magnetic loss decreases gradually with the increase of frequency. The magnetic loss is between 0.05 and 0.15 at the frequency ranging from 2 to 6 GHz. The research has shown that Dravite/ZnO complex powder exhibits some microwave absorbing capability, which may widen the application of tourmaline in the field of environmental depollution.

Abstract: Poly (L-lactide-co-D/L-lactide)-based fiber meshes resembling structural features of the native extracellular matrix have been prepared by electrospinning. Subsequent coating of the electrospun fibers with an ultrathin plasma polymerized allylamine (PPAAm) layer changed the hydrophobic nature of the polylactide surface into a hydrophilic polymer network and provided positively charged amino groups on the fiber surface able to interact with negatively charged pericellular matrix components. Cell experiments in vitro using different types of human epithelial cells (gingiva, uroepithel) revealed that the PPAAm-activated surfaces promoted the occupancy of the meshes by cells accompanied by improved initial cell spreading. An in vivo study in a rat intramuscular implantation model demonstrated that the local inflammatory tissue response did not differ between PPAAm-coated and untreated polylactide meshes.

Abstract: Coated Al₂O₃ thin film on the surface of the carbon sulfur composite material by liquid phase impregnation method, then made physical and chemical properties and electrochemical performance analysis on the coated carbon sulfur composite materials.Al₂O₃ reduce the direct contact of the carbon sulfur composite materials and electrolyte, reducing the erosion of electrolyte on cathode materials, improve the cycle performance of carbon sulfur composite material. 0.1C in the 2.1~3.2v cycle 20 to 100 times. The capacity retention rate increased from 70% to 90% after coating.

Abstract: This paper focuses on performance of polyethersulfone (PES) ultrafiltration membrane coated with titanium dioxide (TiO₂) nanoparticles and irradiated with UV light. The flat sheet membrane was prepared via phase inversion method, with two types of membrane; TiO₂ coated PES membrane and UV irradiated TiO₂ coated PES membrane. TiO₂ suspension with concentration of 0.01, 0.03 and 0.05 wt.% were prepared and coated on the PES surface via dip coating. Membrane was immersed in all suspension for 15 minutes and 30 minutes. Then, prepared coated membranes were irradiated by 184 Watts UV lamp for 15 minutes. The performance of membranes was examined by permeation of humic acid. The morphology of membranes was analyzed by scanning electron microscopy (SEM). It was revealed that the pure water flux and humic acid permeation of UV irradiated TiO₂ coated membrane was higher than TiO₂ coated membrane. It can be concluded that TiO₂ coated with 0.03 wt.% of suspension, 30 minutes and 15 minutes UV irradiation with 184 Watt light were determined as the optimum conditions for preparation ultrafiltration PES membrane.