In the present paper, the complete ternary Al–Mo–Ti system is thermodynamically modelled based on novel experimental information reported in the literature within the past few years. A series of key ...experiments were performed in addition with selected alloys in order to complement the available data on phase transformation temperatures. Eighteen alloys were prepared and analysed in as-cast and annealed conditions by means of SEM/EDS, XRD and DTA/DSC techniques. The elaborated thermodynamic description was applied to calculate selected phase equilibria as to provide a comparison between calculated and experimental results. The calculations are shown to reproduce the main experimental data reasonably.
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•Investigations of 18 alloys by SEM, XRD and DTA/DSC techniques.•Thermodynamic re-modelling of the complete Al-Mo-Ti system.•Comparison of calculated and experimental results.
In this study, structural, thermal, and hydrogen (H
) adsorption properties of natural analcime-rich zeolite tuff (A) from Trakya (Turkey) and that of acid-treated forms investigated. Analcime ...mineral was treated with 0.1, 0.5, 1, 2, and 3 M HCl solutions at 80 °C for 5 h. Differences in structural and thermal behaviors of the analcime samples before and after acid-treatment were examined by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy with detector x-ray energy dispersive (SEM-EDX), thermal analysis (TG-DTG-DTA) and nitrogen adsorption methods. Micropore volume, micropore area, and specific surface area values of the acid-treated analcimes were very high compared to the natural analcime sample. It was found that the acid-treated analcime zeolites with a high SiO
/Al
O
ratio exhibited higher H
adsorption capacity and thermal stability. H
adsorption capacities of natural and acid-treated analcimes at 77 K up to 100 kPa were found between 0.255 and 0.632 mmol/g. The hydrogen adsorption capacities of analcime samples increases in the order A < 05HA < 01HA < 1HA < 2HA < 3HA. Additionally, it was determined that the hydrogen adsorption capacity of analcime samples had an almost linear connection to the BET surface areas.
Single crystal of ammonium potassium zinc sulfate hexahydrate hereafter (AKZSH) was successfully grown by the slow evaporation technique. The crystal structure was calculated for the as-grown crystal ...using single crystal diffraction, yet the crystal structure was confirmed by X-ray powder diffraction and the pattern was found to be an intermediate phase between ammonium zinc sulfate hexahydrate and potassium zinc sulfate hexahydrate single crystals. The UV–vis study shows that the crystal has good transparency in the visible light region. Optical energy gap was deduced from Tauc’s plot and it was found to be 4.657 eV. The dispersion of the refractive index is analyzed using Cauchy’s and Wemple-DiDomenico models. Various optical constants were calculated for the grown crystal. Spectral analysis was performed using FTIR and Raman spectroscopy to study the vibrational bands of AKZSH crystal. The confirmation of the exact chemical formula for the single crystal was checked by thermal analysis and atomic absorption spectroscopy to calculate the substitution ratio of ions and the ratio of water molecules in the structure.
Cellulose was extracted from wood dust waste samples of Daniella oliveri and corn cobs by acetic acid and alkaline pretreatment methods, while microcrystalline cellulose (MCC) derivative was produced ...by acid hydrolysis in 2 M HCl. The samples were tested for pH, moisture content, swelling capacities and ash contents. The data obtained were compared with those of commercial MCCs found in the literature. The functional groups in the microcrystalline cellulose derivatives was confirmed by the Fourier transform infrared (FTIR) spectroscopic method with characteristic absorption bands of;–OH stretching at 3416 cm-1; C-H stretching at 2918 cm-1; -OH bending at 1377 cm-1; 1159 cm-1; and C-O-C pyranose ring skeletal vibrations at 1026-1033 cm-1. The crystallinity absorption bands appeared at 1436 and 850 cm-1. The characteristic morphological features were established by scanning electron microscopy (SEM). Furthermore, the crystallinity of the microcrystalline cellulose was further confirmed using the X-ray powder diffraction (X-RD) technique, which showed three main reflections at 2θ=14.70°, 22.09°, and 34.24°.These results supported that microcrystalline cellulose derivative as cellulose I type and the acid pretreatment did not affect the structure of the MCC. The crystallinity indices were 69.3 and 73.2%, respectively. Daniella Oliveri and corn cob microcrystalline cellulose are, therefore, potential materials for further processing.
► Aging and thermal behavior of a slurry containing Al microparticles characterized. ► Stablity and decomposition phenomena underlined by FTIR, DSC and DTA/TGA. ► No effect of Al particle size on the ...stability of the slurry with time/temperature. ► Properties of the slurry adequate for aluminizing purposes.
The aging and thermal behavior of an environmentally friendly slurry composed of water, polyvinylalcohol (PVA) and aluminum microspheres for aluminizing superalloy substrates is studied in this work. Different ratios of the slurry components were characterized at room temperature by Fourier-Transformed Infrared Spectroscopy (FTIR), while for the intermediate (<550°C) and high (<1100°C) temperatures differential scanning calorimetry (DSC) and coupled thermo-gravimetric analysis (TGA)/differential thermal analysis (DTA) techniques were respectively employed.
Aging the slurry with time at room temperature confirmed the stability of the solutions up to five days (FTIR). DSC and coupled TGA–DTA allowed to characterize the specific temperature of the organic binder (melting at 220°C and PVA decomposition from 275°C), as well as the deshydroxylation (460°C), melting (660°C) and oxidation reactions associated with the metallic Al in the slurry. Bonding of Al to PVA was confirmed from the broad temperature intervals at which PVA decomposed when compared to pure PVA. The energetic evolutions with temperature for aged and unaged slurries also seemed to be similar regardless of the Al particle size. It is therefore concluded that the slurries remained very stable with time and their evolution with temperature could allow successful application to aluminize superalloy substrates.
Thermogravimetry coupled with thermal analysis and quadrupole mass spectroscopy TGA/DTA-QMS were primarily used to assess the oxidation susceptibility of a pool of nanocrystalline powders of the ...semiconductor kesterite Cu2ZnSnS4 for prospective photovoltaic applications, which were prepared via the mechanochemically assisted synthesis route from two different precursor systems. Each system, as confirmed by XRD patterns, yielded first the cubic polytype of kesterite with defunct semiconductor properties, which, after thermal annealing at 500 °C under neutral gas atmosphere, was converted to the tetragonal semiconductor polytype. The TGA/DTA-QMS determinations up to 1000 °C were carried out under a neutral argon Ar atmosphere and under a dry, oxygen-containing gas mixture of O2:Ar = 1:4 (vol.). The mass spectroscopy data confirmed that under each of the gas atmospheres, a distinctly different, multistep evolution of such oxygen-bearing gaseous compounds as sulfur oxides SO2/SO3, carbon dioxide CO2, and water vapor H2O was taking place. The TGA/DTA changes in correlation with the nature of evolving gases helped in the elucidation of the plausible chemistry linked to kesterite oxidation, both in the stage of nanopowder synthesis/storage at ambient air conditions and during forced oxidation up to 1000 °C in the dry, oxygen-containing gas mixture.
•Almost fully dense HDPE-TiO2 composites could be produced by compression molding.•The hardness of the HDPE increased to 69 MPa with TiO2.•Improvement in thermal stability of HDPE with TiO2 ...reinforcement .•The dielectric constant of HDPE significantly increased from 5.31 to 20.02 with TiO2 addition.•TiO2 is an effective additive in improving dielectric properties and thermal stability of HDPE.
For the first time, the dielectric and thermal behavior of TiO2 (up to 40 vol%) reinforced HDPE was investigated. TGA-DTA analysis shows improvement in thermal stability of HDPE with the addition of TiO2. The dielectric constant (κ) of HDPE and HDPE-10TiO2 slightly increased with increasing frequency and it decreased for other HDPE composites. On the other hand, the dielectric loss of HDPE samples significantly lowered and is stable with increasing frequency. More importantly, the dielectric constant of HDPE increased from 5.31 to 20.02 (at 1 κHZ) with TiO2 filler, and is the highest ever achieved for HDPE materials.
A new organic optical limiting material, ethylenediaminium picrate (EDAPA) was synthesized through acid base reaction and grown as single crystals by solvent evaporation method. Single crystal XRD ...analysis showed that EDAPA crystallizes in orthorhombic system with Cmca as space group. The formation of charge transfer complex during the reaction of ethylenediamine and picric acid was strongly evident through the recorded Fourier Transform Infra Red (FTIR), Raman and Nuclear Magnetic Resonance (NMR) spectrum. Thermal (TG–DTA and DSC) curves indicated that the material possesses high thermal stability with decomposition temperature at 243°C. Optical (UV–Visible-NIR) analysis showed that the grown crystal was found to be transparent in the entire visible and NIR region. Z-scan studies with intense short pulse (532nm, 5ns, 100µJ) excitations, revealed that EDAPA exhibited two photon absorption behaviour and the nonlinear absorption coefficient was found to be two orders of magnitude higher than some of the known optical limiter like Cu nano glasses. EDAPA exhibited a strong optical limiting action with low limiting threshold which make them a potential candidate for eye and photosensitive component protection against intense short pulse lasers.
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•Ethylenediaminium picrate (EDAPA) was synthesized and grown as single crystals by solvent evaporation.•EDAPA crystallizes in orthorhombic system with Cmca as space group.•The formation of charge transfer complex and molecular arrangement was studied by vibrational spectroscopy.•EDAPA exhibits two photon absorption action under short pulse laser excitation (532nm, 5ns, 10Hz, 100µJ).•EDAPA possess high nonlinear absorption co-efficient of 1.80×10−10m/W and low limiting threshold of 2.5×1012W/m2.
The thermal behaviour of astrakanite was investigated by conventional thermal analysis techniques in air and by constant rate thermal analysis (CRTA) under residual water vapour pressure above the ...sample
P
H
2
O
=
5
hPa. It has been shown that the pathway of the thermal dehydration depends strongly on the nature of atmosphere above the sample. A correlation between structure evolution and thermal behaviour was developed. The apparent activation energies corresponding to the two dehydration steps of Na
2
Mg(SO
4
)
2
·4H
2
O were also measured experimentally by means of two CRTA curves and were found equal to 83 ± 7 and 111 ± 8 kJ mol
−1
, respectively.
Some new polythiols were derived from aromatic aldehyde (2-hydroxy benzaldehyde) and different diamines (semicarbazide, 4-phenyl, 3-thiosemicarbazide, 4-4'-oxydianiline and N, N'-dimethyl ...p-phenylenediamine), in the presence of elemental sulphur. The process of condensation is carried out by the Willgerodt Kindler (WK) reaction of azomethine donor or derivatives with elemental sulphur in the presence of a strong base as a catalyst. The polythiols (polythioamides) were characterized by different techniques like elemental micro analysis, FTIR, UV-Vis spectroscopies, thermal analysis and viscosity measurement. The FT-IR showed the main hand around 1235-1265/cm.sup.-1 because of the formation of thiol groups in respected polythiols to vC=S vibrations. The polythiols indicated improved thermal solidity up to 600 degreesC. These polythiols were soluable in highly polar organic solvents due to their complex structures. The intrinsic visco-metrical data of these polythiols reached about 0.393-0.5201 dL/g in THF. Keyword: polythiols, synthesis, Willgerodt Kindler (WK) reaction, FT-IR, TG/DTA, enthalpy
