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Selectively Photocatalytic Oxidation of Low Concentration Methane over Graphitic Carbon Nitride Decorated Tungsten Bronze Cesium
摘要： Although the traditional thermal catalysis is usually used to convert the methane into value-added products, its high reaction temperature results in low performance-price ratio in conversion of low concentration methane. In this regard, we synthesized a series of mace-like g-C3N4 decorated Cs0.33WO3 nanocomposites for photocatalytic conversion of low concentration methane under mild conditions. The optimized g-C3N4@Cs0.33WO3 (weight ratio = 3:7) photocatalyst selectively converted low concentration methane (1000 ppm) into methanol with yield of 4.38 μmol/h/g under light irradiation and at room temperature. Both performance experiments and trapping experiments verified that the methane activation and methyl oxidation involved in photocatalytic conversion process of methane. The ?O2- firstly activated the methane to methyl on the surface of the g-C3N4 in the composite and then the photogenerated electrons from the Cs0.33WO3 in the composite inhibited the peroxidation and increased the generation of methanol. This research provides a new route to design and synthesize photocatalysts for converting methane into value-added chemicals.
关键词： Selective Conversion,Low concentration methane,Tungsten Bronze Cesium,Photocatalytic Methane Conversion,Graphic Carbon Nitride
更新于2025-09-19 17:15:36
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Study on Effect of Post Processing on Direct Metal LASER Sintered 420 Stainless steel Infiltrated with Bronze
摘要： Additive manufacturing (AM) of metals is increasing its potential applications in the areas of aerospace, automobile, defense and medical with the processing capability from light to heavy metals, but still low density of the finished products which causes discrimination to functional properties and thus reducing AM process real time efficiency. Current research focus on improving the functional properties of 420 stainless steel specimens which are fabricated by Direct Metal LASER Sintering (DMLS) process and infiltrated with bronze for improving the density. Also post processing i.e. annealing, deep cryogenic treatment and tempering was performed. By studying the mechanical properties like tensile strength, hardness, wear of material of specimens in as fabricated and post processed condition it was observed that post processing treatment will favours in enhancing the functional properties. Also results are compared with SEM and optical microscopy images in order to determine microstructural changes.
关键词： deep cryogenic treatment,Infiltration with bronze,Additive manufacturing,420 stainless steel,annealing,tempering
更新于2025-09-16 10:30:52
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Formation of Antifriction Alloys on the Metal Materials Surface by Laser Radiation
摘要： In this paper, we present the results of an investigation of the production of antifriction coating based on tin bronze using continuous laser radiation. The powder material was uniformly distributed on a copper substrate and subjected to laser melting under various experimental conditions. X-ray diffraction analysis of the obtained samples was carried out, topology, morphology and tribology of the surface were studied.
关键词： powder,laser action,morphology,bronze coating,melting
更新于2025-09-12 10:27:22
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Photoluminescence and ferroelectric behaviors related to Sr/Ba ratio in Eu3+ doped (Sr Ba1-)0.98Eu0.02Nb2O6 multifunctional tungsten bronze ceramics
摘要： The lead-free Eu3+ doped (SrxBa1-x)0.98Eu0.02Nb2O6 (SBEN, 0.3 (cid:2) x (cid:2) 07) ceramics were fabricated by conventional solid-state reaction method. Eu3+ was chosen as a dopant with the goal of inducing strong red-emitting photoluminescence based on their electrical properties. Effects of Sr/Ba ratio on the crystal structure, dielectric, ferroelectric and photoluminescent properties of SBEN ceramics were investigated by changing x. Single tungsten bronze structure with P4bm space group was obtained for all ceramics. The ceramics grain morphology varied obviously from homogenous equiaxed shape to anisometric pillar-type shape with increasing x. According to the dielectric spectra, the obtained SBEN ceramics transited from normal ferroelectrics to relaxor ferroelectrics, accompanied by the gradual decrease of Tm with increasing Sr2+ amount in A-sites. Two strong emitting peaks corresponding to the orange magnetic dipole transitions (594 nm, 5D0/7F1) and red electric dipole transitions (618 nm, 5D0/7F2) were obtained for all SBEN ceramics. The red/orange-emitting ratio of Eu3+ related to the Sr/Ba ratio in the composition was studied in this work to discuss the ions occupying situation in different A-sites.
关键词： Relaxor ferroelectrics,Dielectric properties,Luminescence,Tungsten bronze structure
更新于2025-09-10 09:29:36
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On the formation features, structure, microhardness and tribological behavior of single tracks and coating layers formed by laser cladding of Al-Fe powder bronze
摘要： In this paper, the effect of the gas flow and pressure on the powder flow, as well as the effect of the conditions of laser cladding on the microstructure, phase composition, microhardness and tribological behavior of an Al-Fe powder bronze coating, is studied. The features of single tracks, single- and double-layer coatings are described. The speed of a laser beam, the pitch of the single track and the distance between the nozzle and the coated surface affect the microstructure and microhardness of the coating. These parameters are more stable for double-layer coatings because a denser coating with better fusing along the grain boundaries is formed as a result of secondary melting. Under dry friction conditions, with deposition speeds less than 140–160 mm/min, the coefficient of the friction is stable and significantly lower compared with cast aluminium bronzes. In such conditions, the wear resistance of the coating increases with the increase in deposition speed. With further speed increases, a substantial rise in the friction coefficient in time and a substantial seizure of friction surfaces are observed. Under lubricated friction conditions, when the load increases from 120 N to 360 N, that is, where the pressure on the contact surface increases from 1.75 to 5.3 MPa, a sharp increase in the wear rate occurs with a deposition speed of 120 mm/min almost 130-fold and for a speed of 140 mm/min ~9-fold.
关键词： Al-Fe bronze,Powder flow,Single- and double-layer coating features,Laser cladding,Tribological behavior,Single track features
更新于2025-09-09 09:28:46
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Ultrathin tungsten bronze nanowires with efficient photo-to-thermal conversion behavior
摘要： In this work, we describe a simple one-step solvothermal method to synthesize ultrathin quaternary tungsten bronze nanowires (QTBNWs). In addition, a series of alkali metal-doped QTBNWs can be prepared by simply changing the type of starting alkali carbonate and tungstate. The as-synthesized QTBNWs exhibits strong near-infrared (NIR) rays absorption, high visible light transmission and excellent photo-to-thermal conversion behavior, which are superior to those of tungsten bronze nanorods and ternary TBNWs. And its excellent photothermal performance should be attributed to great localized surface plasmon resonances (SPR).
关键词： solvothermal method,photo-to-thermal conversion,near-infrared absorption,ultrathin tungsten bronze nanowires,surface plasmon resonances
更新于2025-09-09 09:28:46
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[Ceramic Transactions Series] Proceedings of the 12th Pacific Rim Conference on Ceramic and Glass Technology (Ceramic Transactions) || Recent Topics in the Field of Ferroelectric Materials for BME-MLCCs
摘要： The present paper focuses on the recent direction of materials technology for Base Metal Electrode (BME)-Multilayer Ceramic Capacitors (MLCCs). Recently, technologies are accelerating in the area of miniaturization, high capacitance, and reduction of production cost of MLCCs, in order to meet the requirements of the electronics market. In order to maintain high capacitance values with smaller case sizes, reduction in thickness and the multiplication of the dielectric layers have been advancing. Thinning dielectric layers, however, has a deleterious effect on the dielectric performance and it is considered getting closer to dimensional limit. So far, temperature stable MLCCs of high capacitance such as X7R, X7S, and X7T specifications in EIA-STD have been employing BaTiO3 based ferroelectric materials. In the case of BaTiO3 based ferroelectrics, X8R characteristics may be a limit for temperature stable MLCCs, because Curie temperature of BaTiO3 is around 120-130oC. Under these circumstances, numerous studies have been devoted to ferroelectric materials such as giant dielectric constant (K) materials, high TC materials of high K, and high withstanding voltage materials. In this paper, these challenges in the field of dielectric materials for MLCCs are reviewed, and a potential of filled tungsten-bronze-type ferroelectrics for high capacitance BME-MLCCs of X9R specification (ΔC/C25 ±15%, -55~200oC) are proposed.
关键词： BME-MLCCs,X9R specification,ferroelectric materials,tungsten-bronze-type ferroelectrics,BaTiO3
更新于2025-09-04 15:30:14