scholarly journals Synthesis of Hierarchical Zeolites with Morphology Control: Plain and Hollow Spherical Beads of Silicalite-1 Nanosheets

Molecules ◽  
2020 ◽  
Vol 25 (11) ◽  
pp. 2563 ◽  
Author(s):  
Kassem Moukahhal ◽  
Bénédicte Lebeau ◽  
Ludovic Josien ◽  
Anne Galarneau ◽  
Joumana Toufaily ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Hollow Spheres ◽  
Crystallization Rate ◽  
Treatment Temperature ◽  
Pure Silica ◽  
Spherical Silica ◽  
Silica Beads ◽  
Different Temperatures ◽  
Local Dissolution ◽  
Amorphous Part

Binderless pure silica zeolites (zeosils) spheres and hollow spheres with a diameter of 20 µm composed of silicalite-1 nanosheets particles were prepared by pseudomorphic transformation of spherical silica beads using different temperatures (110, 130, and 150 °C) and treatment times (1–5 days) in order to adapt the local dissolution rate of silica to the crystallization rate of silicalite-1 nanosheets allowing to preserve the initial morphology of the silica beads. Fully crystalline beads of 20 µm were obtained at 110 °C for 5 days, whereas hollow spheres similar in size were synthesized at higher temperatures. The crystallization process seems to begin at the outer surface of the amorphous silica beads and spreads with the time in the interior of the beads leading to a dissolution of the inner amorphous part of the beads to create zeosil hollow spheres for the highest treatment temperatures (130 and 150 °C). The dissolution rate of the inner amorphous part of the beads increases by increasing the hydrothermal treatment temperature from 130 to 150 °C. The silicalite-1 beads synthesized at 110 °C for 5 days showed to be promising for rapid molecular decontamination by adsorbing n-hexane in larger amount than the silicalite-1 conventional big crystals in powder forms.

Application of MeV Ion Implantation in the Formation of Nano-Metallic Clusters in Silica

1996 ◽  
Vol 457 ◽  
Author(s):  
D. Ila ◽  
Z. Wu ◽  
R. L. Zimmerman ◽  
S. Sarkisov ◽  
C. C. Smith ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Optical Absorption ◽  
Rutherford Backscattering Spectrometry ◽  
Treatment Temperature ◽  
Gold Clusters ◽  
Third Order ◽  
The Third ◽  
Pure Silica ◽  
Photorefractive Materials ◽  
Electric Susceptibility

ABSTRACTThe implantation of metal ions into photorefractive materials followed by thermal annealing leads to an increase in resonance optical absorption as well as an enhancement of the nonlinear optical properties. We have implanted ions of Au (3.6 MeV), Ag (1.5 MeV) and Cu (2.0 MeV) into pure silica followed by careful heat treatment. Using optical absorption spectrophotometry and rutherford backscattering spectrometry we have measured the cluster size for each heat treatment temperature and determined the activation energies for their formation. The third order electric susceptibility for silica with 2 nm gold clusters has been determined by Z-scan to be 65×10−8 esu.

scholarly journals EFFECTS OF ADMIXTURES ON THE CRYSTALLISATION RATE OF GYPSUM A BATCH CRYSTALLISATION STUDY

REAKTOR ◽  
2017 ◽  
Vol 8 (2) ◽  
pp. 85
Author(s):  
S. Muryanto ◽  
H. M. Ang
Keyword(s):  
Equilibrium Concentration ◽  
Crystallization Rate ◽  
Supersaturated Solution ◽  
Different Types ◽  
Different Temperatures ◽  
Copper Zinc ◽  
Time Required ◽  
Crystallisation Rate ◽  
Zinc Concentrate ◽  
Concentrate Production

This paper descripbes a study on the effects of admixtures on the crystallization rate of gypsum. Two different types of biodegradable admixtures commonly used as flotation agent in copper/zinc concentrate production, namely, sodium isopropyl xanthate (=SIPX) and isopropyl thionocarbamate were investigated in this study. A laboratory batch crystallizer was used in this study, and the experiments were run using seeded method. The rate of desupersaturation or the time required to reach the equilibrium concentration was  compared for varying admixture oncentrations. It was discovered that the added seed crystals started growing imediately upon addition into the supersaturated solution, i.e. there  was no induction time.Results of this batch crystallizationstudy suggest that addition of admixtures individually or in combination, significantly affects the crystallization kinetics and in particular, reduces the rate of crystallization of gypsum. Activation energies were determined using three different temperatures, and the values obtained  mostly agreed with other published values, i.e. 60.00 ± 3.00, 57.39 ± 2.87, and 37.65 ±1.88 kj/mol, for pure gypsum, isopropyl yhionocarbamate, and SIPX, respectively.Keywords : activation energy; admixtures; CaSO4.2H2O; crystallization, gypsum; reaction rate

scholarly journals A Comparison of the Ballistic Performances of Various Microstructures in MIL-A-12560 Armor Steel

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 446
Author(s):  
Erkan Konca
Keyword(s):  
Treatment Temperature ◽  
Energy Losses ◽  
Tempered Martensite ◽  
Ballistic Protection ◽  
Different Temperatures ◽  
Armor Steel ◽  
Isothermal Heat Treatments ◽  
Bainite Microstructure ◽  
Impact Energies ◽  
Martensite Microstructure

Due to their advantageous properties, there is a growing interest in developing armor steels containing fully or partially bainitic microstructures. In this study, bainitic and martensitic microstructures were obtained in rolled homogeneous armor (RHA) steel samples and their ballistic protection performances were investigated. RHA (MIL-A-12560) steel samples were subjected to isothermal heat treatments at three different temperatures, where one temperature (360 °C) was above the martensite formation start (Ms) temperature of 336 °C while the other two (320 °C and 270 °C) were below. For the assessment of the ballistic protection performance, the kinetic energy losses of the 12.7 mm bullets fired at the test samples were determined. The promising nature of the bainite microstructure was confirmed as the sample isothermally treated at 360 °C provided approximately 10% higher ballistic protection as compared to the regular RHA sample of tempered martensite microstructure. However, the ballistic performances of the isothermally treated samples decreased as the treatment temperature went below the Ms temperature. Following the ballistic tests, hardness measurements, impact tests at −40 °C, and macro- and microstructural examinations of the samples were performed. No correlation was found between the hardness and impact energies of the samples and their ballistic performances.

scholarly journals Effect of Heat Treatment Temperature on Martensitic Transformation and Superelasticity of the Ti49Ni51 Shape Memory Alloy

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2539 ◽  
Author(s):  
Peiyou Li ◽  
Yongshan Wang ◽  
Fanying Meng ◽  
Le Cao ◽  
Zhirong He
Keyword(s):  
Heat Treatment ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Thermal Hysteresis ◽  
Treatment Temperature ◽  
Heat Treated ◽  
Different Temperatures ◽  
Tini Phase ◽  
Rapidly Solidified

The martensitic transformation and superelasticity of Ti49Ni51 shape memory alloy heat-treatment at different temperatures were investigated. The experimental results show that the microstructures of as-cast and heat-treated (723 K) Ni-rich Ti49Ni51 samples prepared by rapidly-solidified technology are composed of B2 TiNi phase, and Ti3Ni4 and Ti2Ni phases; the microstructures of heat-treated Ti49Ni51 samples at 773 and 823 K are composed of B2 TiNi phase, and of B2 TiNi and Ti2Ni phases, respectively. The martensitic transformation of as-cast Ti49Ni51 alloy is three-stage, A→R→M1 and R→M2 transformation during cooling, and two-stage, M→R→A transformation during heating. The transformations of the heat-treated Ti49Ni51 samples at 723 and 823 K are the A↔R↔M/A↔M transformation during cooling/heating, respectively. For the heat-treated alloy at 773 K, the transformations are the A→R/M→R→A during cooling/heating, respectively. For the heat-treated alloy at 773 K, only a small thermal hysteresis is suitable for sensor devices. The stable σmax values of 723 and 773 K heat-treated samples with a large Wd value exhibit high safety in application. The 773 and 823 K heat-treated samples have large stable strain–energy densities, and are a good superelastic alloy. The experimental data obtained provide a valuable reference for the industrial application of rapidly-solidified casting and heat-treated Ti49Ni51 alloy.

Synthesis and Characterization of Multi-Angular Branched ZnO Microstructures and Peculiar Nanopushpins Obtained by Thermal Treatment from Compacted ZnS Powder

2019 ◽  
Vol 286 ◽  
pp. 23-30
Author(s):  
J.R. Mora ◽  
Gregorio Flores-Carrasco ◽  
Mauricio Pacio ◽  
T.G. Díaz-Rodríguez ◽  
Hector Juárez
Keyword(s):  
Thermal Treatment ◽  
Treatment Process ◽  
Treatment Temperature ◽  
Complex Structures ◽  
Wurtzite Phase ◽  
Free Process ◽  
Different Temperatures ◽  
Short Time ◽  
Hexagonal Wurtzite Phase

Multi-angular branched ZnO microstructures with rods-shaped tips and nanopushpins with hexagonal cap on top have been synthesized by a simple thermal treatment process of compacted ZnS powder used as starting material and substrate. The structures have been grown at different temperatures (800, 900 and 1000 °C) for 60 min, in a constant nitrogen environment at atmospheric pressure via a catalyst-free process. XRD results of the as-grown products from ZnS powder show a significant reduction in the cubic zincblende phase to the hexagonal wurtzite phase with the increase of treatment temperature, as compared to the bulk value. Post-anneal analyses indicated that the transformation of morphologies of the as-grown structures also depends strongly on the treatment temperature. The proposed method represents an easy and economical way to grow complex structures of ZnO, with a relatively short time, furthermore, without the neediness of use an external substrate to grow. These new and interesting nanostructures have potential in applications such as optoelectronics.

Effect of manufacturing parameters and thermal treatment on the properties of tubular braids and tubular knits

2016 ◽  
Vol 36 (4) ◽  
pp. 421-430
Author(s):  
Ching-Wen Lou ◽  
Po-Ching Lu ◽  
Jin-Jia Hu ◽  
Jia-Horng Lin
Keyword(s):  
Thermal Treatment ◽  
Three Dimensional ◽  
Textile Composites ◽  
Treatment Temperature ◽  
Test Results ◽  
Thermal Treatment Temperature ◽  
Medical Textiles ◽  
Different Temperatures ◽  
Conductive Textile ◽  
Manufacturing Parameters

Abstract Textile techniques can be applied to create two-dimensional or three-dimensional tubular fabrics. Three-dimensional tubular knits can be used in many fields, such as for medical textiles, conductive textile, composites, and tissue engineering. This study aimed to examine the effects of different yarn types on various fabrics and of different temperatures on the variations in the properties of textiles. Four types of wrapped yarn (P150, P75, S140, and S70) were made into tubular braids and knits, after which the products were thermally treated at various temperatures (120°C, 140°C, and 160°C). A shrinkage measurement, a porosity test, a braid angle test, and a tensile test were performed to evaluate the tubular braids and knits. The test results indicated that the thermal treatment temperature did not affect the porosity of the tubular braids and tubular knits. The porosity of the tubular braids was between 40.32% and 48.27%, while that of the tubular knits was between 10.15% and 35.57%. In addition, the tensile strength of both fabric types increased by 40–50%, while their displacement increased by 200–250%. In the future, the efficacy of tubular braids and tubular knits for use as vascular grafts will be examined.

Structural and Photoluminescent Properties of Li-Doped ZnO Film Prepared by Sol-Gel Technique

2010 ◽  
Vol 663-665 ◽  
pp. 397-400 ◽  
Author(s):  
Peng Fei Cheng ◽  
Sheng Tao Li ◽  
Han Chen Liu ◽  
Li Xun Song ◽  
Bin Gao ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Sol Gel ◽  
Treatment Temperature ◽  
Zno Films ◽  
Zno Film ◽  
Substitutional Defect ◽  
Different Temperatures ◽  
Abnormal Phenomenon ◽  
Doped Zno ◽  
Li Content

The effect of an impurity as a donor or an acceptor in ZnO film is determined by its distribution in ZnO lattice. In this paper the distribution of Li is investigated by X-ray diffraction (XRD) and photoluminescence (PL). It is found that Li-doped ZnO films own different dependence on heat treatment temperature by contrast with pure ZnO films. For Li-doped ZnO films, although the crystallinity is promoted after heat treatment at 500oC, it is impeded effectively after heat treatment at 600oC. The abnormal phenomenon implies that Li preferential inhabits at Zn-sublattice to form a substitutional defect as an acceptor unless Li content exceeds its solubility in Zn-sublattice. The change of the PL spectra of pure ZnO films after heat treatment at different temperatures reveals that the PL peak at 650nm origins from interstitial defects. Moreover, with the increase of Li content, the intensity of the peak at 650nm decreases firstly and then increases again. This interesting changing trend further reveals that superfluous Li will enter into the octahedral interspaces as donors. As a conclusion it is proposed that it is difficult to obtain high conductive p-ZnO by monodoping of Li.

Investigation on the Influence of Precipitated Phase on Corrosion Resistance of the Ni-Based Alloys

2012 ◽  
Vol 184-185 ◽  
pp. 1038-1043
Author(s):  
Xue Hui Zhao ◽  
Zhen Quan Bai ◽  
Yao Rong Feng ◽  
An Qing Fu
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Corrosion Resistance ◽  
Electron Microscope ◽  
Grain Boundaries ◽  
Aging Treatment ◽  
Treatment Temperature ◽  
Different Temperatures ◽  
Metallographic Observation ◽  
Precipitated Phases

The influence of precipitated phases in Ni-based alloys during solid solution aging treatment on the performance of Ni-based alloys was investigated by means of metallographic observation, scanning electron microscope (SEM), and transmission electron microscope (TEM). The variation of microstructure and resultant phases as a result of solid solution aging treatment at different temperatures was discussed. The results show that the heat treatment temperature has significant influences on the type as well as quantity of precipitation phases. Lots of phases precipitated at grain boundaries, the distribution of precipitated phases are characterized by mesh-like structure. The corrosion tests results indicate that there is a potential difference between grains and grain boundaries due to the precipitation of chrome carbide at grain boundaries, resulting in pitting corrosion occurred preferentially at grain boundaries, consequently, the corrosion resistance of Ni-based alloys is reduced. In order to enhance the corrosion resistance of Ni-based alloys, it is expected to control the carbon content in a lower range and proper heat treatment process to avoid large amount precipitation of chrome carbide.

Characteristics of 45S5 Bioglass-Ceramics Using Natural Raw Materials

2012 ◽  
Vol 506 ◽  
pp. 174-177
Author(s):  
W. Leenakul ◽  
N. Pisitpipathsin ◽  
P. Kantha ◽  
N. Tawichai ◽  
S. Tigunta ◽  
...  
Keyword(s):  
Raw Materials ◽  
Glass Ceramics ◽  
Treatment Temperature ◽  
Phase Identification ◽  
Bovine Bone ◽  
In Vitro Test ◽  
Phase Form ◽  
Different Temperatures ◽  
Optimum Heat

The aim of this work was to analyze the effect of using rice husk ash (RHA) and bovine bone as raw materials of glass-ceramics based on the SiO2-Na2O-CaO-P2O5system on their physical, mechanical properties and bioactivity. All of the investigated compositions were prepared by melting the glass mixtures at 1300°C for 3 h. The resulting glass samples were heated at different temperatures ranging from 600 to 1000°C with fixed dwell-time for 2 h for crystallization. Phase identification of the prepared glass ceramics was carried out by X-Ray diffraction (XRD) and scanning electron microscope (SEM) techniques. In addition, in vitro test was carried out in stimulated body fluid (SBF). Differential thermal analysis (DTA) showed that the glass transition occurred at 505°C and crystallization at 700°C. The main crystalline phase form in most glass ceramics is a sodium calcium silicate. The optimum heat treatment temperature, at which the maximum mechanical value (620 HV) could be obtained, is around 1000°C. After incubation in SBF for 7 days, all of the samples show good bioactivity in vitro, as evident by the formation of bone like apatite phase.

scholarly journals Determination of the effect of exposure conducted in KOH solutions at different temperatures on the properties of electrochromic Ni(OH)2-PVA films

2021 ◽  
Vol 4 (6(112)) ◽  
pp. 60-66
Author(s):  
Valerii Kotok ◽  
Vadym Kovalenko ◽  
Rovil Nafeev ◽  
Volodymyr Verbitskiy ◽  
Elena Lominoga ◽  
...  
Keyword(s):  
Treatment Temperature ◽  
Electrochemical Activity ◽  
Operating Conditions ◽  
Electrochromic Device ◽  
Electrochemical Characteristics ◽  
Composite Electrodes ◽  
Hot Climate ◽  
Different Temperatures ◽  
Temperature Ranges ◽  
Electrochemical Cycling

To determine the effect of exposure of film composite electrodes based on Ni(OH)2-polyvinyl alcohol to an alkaline solution at high temperatures on the electrochromic and electrochemical characteristics, a series of films was obtained. The films were obtained on a glass substrate coated with fluorine-doped tin oxide. The coating of the substrates was carried out by the cathodic template method under the same conditions. The resulting precipitates were treated by keeping them in an alkali solution at different temperatures: 30, 40, 50, 60, and 70 °C for 8 hours, thereby simulating the operating conditions of an electrochromic device in a hot climate. It was found that the exposure temperature directly affected the electrochemical and electrochromic properties of the treated films. In this case, the cyclic volt-ampere curves showed a decrease in the peak values of the current densities and a lower rate of establishment of characteristics with an increase in the treatment temperature. At a maximum treatment temperature of 70 °C, the properties of the film significantly changed towards deterioration. According to the results of the experiments, three temperature ranges of treatment were identified. The first one was in the range up to 40 °C, in which the films showed significant electrochromic and electrochemical activity after treatment. The second interval was between 40 and 60 °C, in which the coatings showed a reversible deterioration in electrochromic and electrochemical activity. After treatment in the second interval, the films gradually restored their performance during electrochemical cycling. The third interval was from 70 °C and above. The films treated in this temperature range irreversibly lost their electrochemical and electrochromic activity. The study also proposed mechanisms to explain changes in the characteristics of electrodes during treatment, as well as possible ways to combat temperature degradation.

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