Effect Of Preparation Temperature Research Articles

Effect of preparation temperature on interfacial reactions and mechanical properties of Nbf/TiAl composite

TiAl alloys with low density and outstanding high-temperature mechanical property become potential high temperature structural materials, but the inherent brittleness limits their further utilization. In this paper, 10 vol% of tough Nb fiber was introduced into TiAl alloy by powder metallurgy to improve the room temperature properties. Concurrently, the effect of preparation temperature on interfacial reaction between fiber and matrix was explored, as well as mechanical properties of the composites were investigated systematically. The results show that, a Nbf/TiAl composite without obvious holes and cracks can be synthesized at hot processing conduction of 1150 °C/35 MPa/2 h, whose tensile and bending strength were increased by 36.4% and 24.1%, respectively, compared to those of the monolithic TiAl alloy. The improvement can be attributed to plastic deformation of Nb fiber and weak interfacial debonding resulted from the formation of brittle σ interfacial phase. In addition, more complex interfacial reactions between fiber and matrix occur in the composite prepared at 1200 °C. The phase transition process at the side of TiAl matrix can be described as: γ+Nb → γ/α2+Nb → B2+α2 → B2(γn)+α2, and that at the side of Nb fiber is as follows: Nb + Al → Nb + Nbss → Nb + Nbss+σ(α2) →Nb + Nbss + σ(α2+O). The thicker brittle reaction layer results in serious micro-cracks at interface and even in the matrix, which significantly reduces macromechanical properties of the composite prepared at 1200 °C dramatically.

Effect of preparation temperature on the structure and lithium storage properties of multicomponent composites fabricated by one-step thermal decomposition method from the leaching liquor of jarosite residue

Effect of preparation temperature on the structure and lithium storage properties of multicomponent composites fabricated by one-step thermal decomposition method from the leaching liquor of jarosite residue

The effect of preparation temperature and composition on bigel performance as fat replacers.

Consumer awareness of the deleterious effect of a diet rich in saturated fat pushes the food industry to find new fat alternatives. Bigels, hybrids of hydrogels and oleogels, are an attractive option for formulating oil-based fat mimetics, particularly lamination fats. This research explored the characteristics of a hydrogel-in-oleogel bigel, made of candelilla wax and xanthan gum. This study investigated the effect of homogenization temperature, hydrogel : oleogel phase ratio, and storage conditions on the bigel melting profile, mechanical and rheological properties, stability, and the structural characteristics involved. The optimal homogenization temperature that resulted in a smooth, firm, margarine-like texture was 42 °C while higher homogenization temperatures produced lumpy unspreadable bigels and lower ones produced soft and smooth texture. The bigel behavior was related to the formation of a low mobility biphasic system, stabilized in a Pickering mechanism by wax crystals that crystallize at 47 °C, above the homogenization temperature. The phase ratios tested, 15 : 85 to 45 : 55 hydrogel : oleogel, appeared to have a limited effect on any of the bigel characteristics. More specifically, no significant differences in melting temperature, texture parameters, flow behavior, and stability, which are reminiscent of margarine, were detected. These results indicated that hydrogel droplets may serve as active fillers, strengthening the bigel matrix when their amount in the bigel increases and the oleogel, which is the dominant phase, decreases. These findings provide an understanding of the way bigel properties depend on the formulation and preparation, which is valuable in the development of bigel fat replacers and other novel food applications.

Optimal preparation of molybdenum phosphide cocatalyst for efficient dye-sensitized photocatalytic hydrogen evolution

Searching for non-noble-metal cocatalyst for hydrogen evolution in photocatalytic water–splitting has attracted much attention. Herein, molybdenum phosphide (MoP) as an efficient and stable cocatalyst was prepared in a facile phosphorization process at relatively low temperatures under N2 atmosphere, and the effect of preparation temperature (300–500 °C) was studied. Using Eosin Y (EY) and the prepared sample as catalyst (sensitizer) and cocatalyst, respectively, the photocatalytic activity for hydrogen evolution was investigated in aqueous trimethylamine (TMA) solution under visible light irradiation (λ ≥ 420 nm). MoP prepared at 400 °C (MoP-400) exhibits the highest sensitization activity and superior stability, and the maximal apparent quantum yield (AQY) for hydrogen evolution is up to 48.0% at 420 nm, much higher than the most reported data for MoP-based photocatalysts. The highest activity can be attributed to the highest P content in MoP-400 and the rapidest electron transfer between photoexcited EY and MoP-400. The possible mechanism was discussed.

Mesoporous graphitic carbon nitride for adsorptive desulfurization in an isooctane solution

g-C3N4, a typical 2D material, has been developed as a promising desulfurization adsorbent, and the effect of preparation temperature on the adsorption performance was investigated here. Mesoporous g-C3N4 was synthesized by a hard template method with gel silica as the template agent. The precursor powder was heat-treated for 4 h at different temperatures (500°C, 550°C and 600°C), respectively, named CN-500, CN-550 and CN-600. UV-Vis spectra and X-ray photoelectron spectroscopy spectra prove CN-500 is composed of triazine g-C3N4, whereas CN-600 is partially composed of tri-s-triazine g-C3N4. The max adsorption capacity of CN-600 toward thiophene (TP) is up to 40.82 mg S/g in an isooctane solution, while CN-500 with the maximum specific surface area of 176.5 m2/g shows better selectivity but a smaller adsorption capacity. The robust adsorptive performance of mesoporous g-C3N4 is attributed to the D-A (Donor–Acceptor) interactions between adsorbent and TP, which could be interfered by the π–π interactions or steric effect, leading to a variable adsorptive capacity or selectivity towards TP and its analogs.

Effect of Preparation Temperature, Surfactant, and Nanoparticles Concentration on the Effective Thermophysical Properties of Multi-walled Carbon Nanotubes’ Nanofluids

Effect of Preparation Temperature, Surfactant, and Nanoparticles Concentration on the Effective Thermophysical Properties of Multi-walled Carbon Nanotubes’ Nanofluids

Effect of preparation temperature on the structural, optical and electronic properties of co-doped ZnS nanostructures

In the present work, the effect of preparation temperature on the structural, optical and electronic properties of cobalt doped zinc sulfide (Zn0.95Co0.05S) nanostructures have been explored. Zn0.95Co0.05S nanostructures were synthesized at different preparation temperatures (300, 400 and 500 °C) using the thermolysis method. All samples resembled a single phase cubic zinc blende structure. Upon raising the preparation temperature, the lattice parameter decreases and the anisotropic nature of the crystallite size of the samples is changed into isotropic nature. Rietveld analysis discloses that cobalt (Co) could be incorporated substitutionally for zinc (Zn) ions with occupancies in good agreement with the value intended for preparation. The major characteristic vibration bands of zinc sulfide (ZnS) were determined using Fourier transforms infrared and slightly increased in the wavenumber upon raising the temperature. Ultraviolet–visible spectroscopy technique reveals an increase in the optical band gap upon increasing temperature from 300 to 400 °C, and then it reduces at 500 °C. Different defects in the different samples are concluded using the emission colors obtained from the photoluminescence technique. Density function theory calculation was applied to investigate the different electronic and optical parameters of ZnS and Co-doped ZnS with and without oxygen.

Effects of preparation temperature on production of graphene oxide by novel chemical processing

The effect of preparation temperature on the synthesis of high quality graphene oxide (GO) by a chemical oxidation method has been studied. GO samples have been produced from graphite using a blend of sulfuric and phosphoric acids with a volume ratio of 4:1, where potassium permanganate and hydrogen peroxide were selected as oxidizing agents. The temperature for GO preparation was changed over a range of 20–85 °C. The synthesized GO samples have been characterized by X-ray diffraction, scanning electron microscopy, electron dispersive spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible spectroscopy methods. It was shown that high quality GO can be synthesized at 20 °C but the purity of GO increased with the increase of the preparation temperature. The atomistic models of GO sheets prepared at different temperatures and according to the stoichiometric ratio of the functional groups found by XPS have been developed. Based on the developed models it was found that GO prepared at higher temperatures had more holes in the sheets supported with experimental images.

Tungsten-decorated MoP nanobelts for boosted hydrogen production

To further improve the electrochemical catalytic performance of MoP for hydrogen generation, a tungsten decoration strategy is proposed in this work, and the effect of preparation temperature was also investigated. It is found that the decoration of W can significantly enhance the electron transfer ability and increase the amount of active sites, and the optimized catalyst can be obtained at 700 °C over the Mo-W-P-700 catalyst, which exhibits the best catalytic performance with a small Tafel slope of 53 mV dec-1. This decoration strategy can be widely applied in other transition metal compounds to achieve further performance improvements.

Synthesis and characterization of Cu-BTC metal–organic frameworks onto lignocellulosic fibers by layer-by-layer method in aqueous solution

In the present study, lignin-contained cellulosic fiber material as a substrate was used for immobilizing Cu-BTC metal–organic framework, the composite was strategically synthesized using trimesic salts as linker sources. The growth of Cu-BTC onto lignocellulosic fiber was conducted in aqueous solution by a layer-by-layer method, and the effect of preparation temperature, time, and number of layers of Cu-BTC deposition was also investigated. The products were characterized by ATR FT-IR, XRD, and SEM. The results showed that the as-prepared Cu-BTC in water was partially hydrolyzed phase of Cu-BTC prepared in organic solvents. Cu-BTC metal–organic frameworks were homogeneously immobilized on carboxymethylated high yield pulp fibers (CHFs). Increasing the growth temperature and time would enhance the deposit of Cu-BTC onto fiber surface slightly, however increasing the growth layers would promote the deposit ratio significantly (from 26.17 to 68.59%, 2 layers to 6 layers). The specific surface area of synthesized Cu-BTC@CHFs had a distinct promotion compared with unmodified fibers, showing a certain gas adsorption capacity.

Component controlled synthesis of bimetallic PdCu nanoparticles supported on reduced graphene oxide for dehydrogenation of dodecahydro-N-ethylcarbazole

The unsatisfactory performance with high precious metal dosage of dehydrogenation catalysts has been the bottleneck for the development of liquid organic hydrogen carrier (LOHC). The most representative dodecahydro-N-ethylcarbazole in LOHC also faces the same problem. Here, we report a series of bimetallic PdCu catalysts with different ratios supported on reduced graphene oxide prepared by a facile one-pot synthesis method. The most cost-effective Pd1.2Cu/rGO catalyst with the lowest amount of precious metals in the catalysts reported for dehydrogenation of dodecahydro-N-ethylcarbazole was selected from a series of samples, while maintaining the catalytic activity and selectivity to the final product of N-ethylcarbazole as the Pd/rGO catalyst with the highest activity in recently reported studies. At the same time, the change of Pd and Cu content and the effect of preparation temperature on dehydrogenation performance were also studied, and the corresponding reaction kinetics were revealed. In combination with various characterization methods of catalyst, the relationship between structure and properties of PdCu NPs was explored in depth. The average particle size and electron transfer between Pd and Cu were identified as the key factors affecting the catalytic activity.

A facile preparation of WS2 nanosheets as a highly effective HER catalyst

Tungsten disulfide (WS2) has been considered as a promising hydrogen evolution reaction (HER) candidate due to its high activity, robust chemical stability, and earth-abundant resources. However, the inert basal planes and low electrical conductivity greatly hinder its development in HER. Increasingly, the density of active sites through the structural designing is one of the most effective strategies to enhance the HER performance. Herein, we report a facile one-step hydrothermal method for synthesizing flower-like WS2 nanosheets for highly efficient HER. Besides, the effect of preparation temperature is also been discussed. The optimized WS2 nanosheets exhibit the enhanced HER activity in strong acidic solutions with a low Tafel slope and a good stability. The improvement of the HER performance can be attributed to sheet-like nanostructures, which greatly increase the edge sites and defects, resulting in a high density of exposed active sites. Besides, these sheet-like nanostructures also can make the acidic electrolyte easily accessible to the surface of WS2 and accelerate the electron transfer rate.

Effect of preparation temperature on the structures and hydrodeoxygenation performance of Ni2P/C catalysts prepared by decomposition of hypophosphites

A novel method for preparing Ni2P/C-x catalysts was proposed. The structure and hydrodeoxygenation performance of Ni2P/C-x catalysts were investigated.

Preparation and service performance characterization of Ni/PMN-PT: Effect of preparation temperature

Ni/PMN-PT thin films were prepared by DC megnetron sputtering, and different sputtering temperatures were applied. The crystalline micro-structure and morphology were characterized by XRD, EDS, VSM and SEM. The magneto-electric properties and adhesion strength were measured by force-magneto-electric measurement system and Nano Test Vantage system. The magnetic hystersis loops indicated that the thin film expressed obvious electric-field modulation effect on magnetic properties. By adjusting the sputtering temperature, the crystalline and magnetic properties in Ni/PMN-PT thin film can be improved significantly. In addition, the scratch behavior showed that the critical load values for cracking and failure were significantly related with the sputtering temperature.

Sol–gel solvothermal route to synthesize anatase/brookite/rutile TiO2 nanocomposites with highly photocatalytic activity

In this study, an attempt is done to synthesize anatase/brookite/rutile TiO2 nanocomposites via a simple solvothermal method with hydrochloric acid, dehydrated ethanol, and titanium butoxide in a sol−gel environment. The effect of preparation temperature on the content of each phase, crystallite size, morphology, and photocatalytic activity was systemically studied. The structures of the products prepared under different temperatures were characterized using X-ray diffraction analysis, transmission electron microscopy, Raman spectra, and BET surface area. The optical properties were measured by UV–vis diffuse reflectance spectra. Besides, the photocatalytic activities were evaluated by performing the degradation of rhodamine B azo dye under UV−vis radiation. The results reveal that the content of different phases and crystallite size can be tailored via tuning the solvothermal condition. In addition, the obtained TiO2 nanocomposites are a kind of mesoporous materials and have large BET surface area, narrow pore size distribution, and low band gap, which exhibit excellent photocatalytic performance (of activity about 4.40 times that of Degussa TiO2 P25). Through examining the photocatalytic stability, the obtained TiO2 nanocomposites exhibit a very stable photocatalytic performance. Therefore, the current method to TiO2 preparation could provide a simple and reliable route for developing photocatalytic materials with high photocatalytic activity.

Effect of preparation temperature on the corrosion resistance of waterborne aluminum pigments

PurposeThe purpose of this paper is to evaluate the role of encapsulation temperature on the preparation of silica-encapsulated waterborne aluminium pigments.Design/methodology/approachThe waterborne aluminium pigments were prepared with H2O2 as anchoring agent and siloxane used as precursors in pH = 9.0 medium at different temperatures. The anchorage and compactness of silicon which on aluminium surface were characterized by optical microscopy, scanning electron microscopy and N2 adsorption-desorption. The anticorrosion property was characterized by the volume of produced hydrogen as a function of time.FindingsThe effect of encapsulation temperature on anticorrosion property of aluminium pigments is reflected from the anchorage and the compactness of silica on aluminium surface. Furthermore, when encapsulation temperature is 45-50°C, the silica platelets uniformly anchored on the aluminium surface as a dense film, which show the best anticorrosion property. Lower and higher encapsulation temperatures cause the silica platelets to agglomerate rather than anchor on the aluminium surface, which is unfavourable for the anchorage and the formation of compact silica film. The use of product in waterborne coatings gives a higher glossiness than that of raw material.Research limitations/implicationsOnly pH = 9.0 medium was explored, and the other pH medium could result in different optimum temperatures.Practical implicationsThe investigation results provide theoretical basis for obtaining excellent waterborne aluminium pigments.Originality/valueThe method of investigating corrosion resistance mechanism of aluminium pigments based on anchorage and compactness is novel.

Green synthesis of UV and visible light active TiO2/WO3 powders and films for malachite green and ethylene photodegradation

Powder nanocomposites of TiO2/WO3 are prepared by a simple solid-state thermal procedure from commercial oxide powders and cast thereafter as a film coating on TLC substrate. The WO3 content in the powder composites is varied from 0.5 to 50%. The phase composition and morphology of titania/tungsten composites and films is characterized by SEM and X-ray analysis. The photocatalytic activity of TiO2/WO3 powders is tested in the degradation of malachite green dye in aqueous solutions under UV and visible light irradiation. The effect of preparation temperature on the photocatalytic activity is also investigated. It is found out that the mixed powder of 5%WO3 manifests the best photocatalytic performance. The prepared powder photocatalyst is deposited as a film coating on TLC sheet for gas-phase application. The as-obtained composite coated photocatalysts with 5%WO3 are tested for air purification from ethylene contamination under UV and visible light illumination. The TiO2/WO3 coated photocatalysts show always a higher efficiency in comparison to that of the pure TiO2.

CoNi2S4 nanoparticles as highly efficient electrocatalysts for the hydrogen evolution reaction in alkaline media

The development of highly active non-Pt electrocatalysts with superior stability for the hydrogen evolution reaction (HER) remains a great challenge. Herein, we report CoNi2S4 nanoparticles synthesized by a facile one-pot hydrothermal method as highly efficient electrocatalysts for the HER in strongly alkaline electrolyte for the first time, and the effect of preparation temperature was also discussed systematically. These as-prepared catalysts exhibited superior HER activity compared to other non-noble metal catalysts and the catalyst obtained at 220 °C showed the best activity with the smallest Tafel slope of 85 mV dec−1 and good stability in 1.0 M KOH, making it a promising candidate to replace Pt-based catalysts.

The Effect of Preparation Temperature of Electrolytes on Undoped and Ag-Doped TiO<sub>2</sub> Nanotube Structures

In this work, we present the effect of preparation temperature of electrolytes for fabricating undoped and silver (Ag) doped titanium dioxide (TiO2) nanotubes by the electrochemical anodic oxidation of pure titanium sheets in electrolytes, mixtures of ethylene glycol (EG), ammonium fluoride (NH4F) and deionized water, that contain with different of silver ions. Heat treatment of electrolytes was carried out at 100 °C during preparation process. The morphology and structure of prepared nanotubes were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The structures of TiO2 nanotubes obtained from heat treatment and non-heat treatment of electrolyte solutions and adding silver ions in electrolyte solution are similar. The nanotubes appear in arrays and the diameters of nanotubes were about 92 nm for non-heat treatment electrolyte solution and undoped TiO2 and about 102 nm for heat treatment electrolyte solution and all Ag-doped TiO2 nanotube arrays. When the concentration of silver nitrate (AgNO3) increases, the TiO2 nanotube arrays cracked and are not well arranged.

Retraction Note to: The Effect of Preparation Temperature on the Superconducting Parameters of Cu1−xTlxBa2Ca2Cu3O10−δ Superconductor

Retraction Note to: The Effect of Preparation Temperature on the Superconducting Parameters of Cu1−xTlxBa2Ca2Cu3O10−δ Superconductor