Papers by Keyword: Thermal Treatment

Abstract: Solution quenching and aging are used to thermally treat Ti-6Al-4V, an α+β titanium alloy. Three Ti-6Al-4V alloy plates were subjected to high temperatures and quenched in water, 5% HCL, and 15% HCl in this investigation. As a comparison, a fourth untreated sample was employed. When compared to the untreated samples, the microstructure and strength of the quenched plates revealed an increase in elongation and a decrease in yield strength. An equiaxed increase of α+β was recorded in all post-quenched samples.

Abstract: Lithium metal batteries (LMBs) are promising candidates for next-generation energy storage devices because of their high energy density. However, the formation of dendritic lithium during charge-discharge cycles poses significant safety risks. This study investigates the effects of thermal treatment on the surface morphology and Solid Electrolyte Interphase (SEI) formation of lithium metal anodes using Atomic Force Microscopy (AFM). Lithium metal samples were heat-treated at 100°C for 24 hours and then immersed in an electrolyte solution for different durations. AFM analysis revealed that thermal treatment increases the size and uniformity of nucleation sites. This results in a thicker and more stable native oxide layer. This enhanced layer promotes a more uniform and densely packed SEI, which remains stable over long-term immersion. The findings highlight the potential of thermal treatment to improve the performance and safety of lithium metal anodes by stabilizing the SEI and preventing dendritic growth. This advancement could significantly enhance the practical application of LMBs.

Abstract: The study investigated the effect of iodine-doped pentacene film as a buffer layer in an organic light-emitting diode (OLED). In this study, an ITO (indium tin oxide)-based sample is used as a reference device for comparative purposes. In OLED devices, the buffer layers were deposited using the doping of iodine vapor with the pentacene materials under proper conditions. The thermal treatment of the doped pentacene film results in increasing the conductivity of the buffer layer. Surface morphology for the bilayer anode was carried out by FESEM (Field Emission Scanning Electron Microscope) analysis. In our work, maximum luminance of 2345 cd/m² and current efficiency of 5.4 cd/A are obtained, along with more stability performance under annealing treatment in the device structure of FTO/iodine-doped pentacene (30 nm)/TPD [N, N′-Bis(3-methyl phenyl)-N, N′-diphenylbenzidine] (44 nm)/Alq3 [Tris(8-hydroxyquinoline)aluminum(III)] (52 nm)/LiF (lithium fluoride) (5 nm)/Al (aluminum) (110 nm).

Abstract: In this work the intrinsic and induced defects related to the mechanical strength of 4H-SiC wafer have been investigated by considering substrates having different dislocation density and subjected to different treatments such as thinning process and high temperature bulk and laser annealing. Three point bending test has been performed on die extracted from the substrates in order to calculate the stress σ the die can withstand at breakage (flexural strength). The variation of intrinsic defect density seems does not act to modify the material flexural strength. Conversely, a considerable correlation between the induced defect density and flexural strength has been found.

Abstract: TiO₂ nanofibers were synthesised by means of the electrospun technique, which were annealed at high temperatures to achieve the crystalline phase transformation from amorphous to rutile through anatase and the phase mixture. The chemical stoichiometry of electrospun TiO₂ nanofibers was estimated by EDS, finding that at low annealing temperatures excess of oxygen was detected and at high temperatures excess of titanium that originates oxygen vacancies. The TEM images showed clearly the formation of TiO₂ nanofibers (NF’s) that exhibit a homogeneous and continuous aspect without the presence of crystalline defects, whose surface morphology depends strongly on the annealing temperature. The crystalline phase transformation was studied by Raman spectroscopy, which revealed that annealed TiO₂ NF’s showed a crystalline phase transformation from amorphous, pure anatase, anatase-rutile mixed, to pure rutile as the annealing temperature increased, which was corroborated by X-ray diffraction and high-resolution TEM. The average grain size, inside the NF´s, increased with the crystalline phase transformation from 10 to 24 nm for anatase-TiO₂ and from 30 to 47 nm for rutile-TiO₂, which were estimated by using the Scherrer-Debye equation. By absorbance measurements at room temperature the band gap energy (E_g) was obtained, which is ranged in 3.75-2.42 eV, caused by the amorphous → anatase → anatase-rutile mixed → rutile crystalline phase transformation.

Abstract: Massive coal gangue waste delivers environmental disasters in China. Finding an effective, efficient, practical and value-added approach for large-scale disposal of coal gangue waste is very urgent. In this study, thermal treatment approach was conducted on coal gangue waster with the goal to improve its pozzolanic activity so that considerable replacement of Portland cement can be realized. XRD analysis, IR analysis as well as the evaluation on mechanical properties of mortar specimen were carried out to optimize thermal treatment program. The results indicate that coal gangue waste can be efficiently treated at 850°C in less than 30min to obtain pozzolanic activity of 108% at 7 days and 124% at 28 days. And an industrial product also shows similar improvement in pozzolanic activity to the lab results, and indicates the potential for producing eco-efficient cementitious materials.

Abstract: This study reports the preparation of white mineral trioxide aggregate (WMTA) using precipitate calcium carbonate (PCC) by sol-gel method at various thermal treatments 900, 1100, and 1300 °C. The composition of WMTA included PCC (55% CaO), C₆H₁₆O₃Si-TEOS (21% SiO₂), Al(NO₃)₃⋅9H₂O (2% Al₂O₃), and Bi₂O₃. WMTA 1100 with the highest purity was proven by the presence of C₃S, C₃A, and α-Bi₂O₃ phase in X-ray diffraction patterns. Results show that based on the SEM image WMTA 1100 formed a smaller crystal agglomeration (6-8 µm) and FTIR analysis found Bi-O (BiO₃) vibration in Bi₂O₃ at 1100 and 950 cm^-1, a characteristic of the β-C₂S phase. The radiopacity value of WMTA 1100 resembles ProRoot MTA, namely 6.86±0.36 millimeters of aluminum (mm Al). WMTA 1100 gives the highest compressive strength, smallest solubility, highest pH, and calcium levels in comparison to WMTA 900 and WMTA 1300.

Abstract: The article is devoted to studying the effect of liquid melt treatment with a substance having high affinity with hydrogen – lead-base silumin. Taking into account that gases (hydrogen, nitrogen and oxygen) are present everywhere, including alloys, a series of experiments was carried out on treating melt of blast furnace iron with substances having great affinity with hydrogen. It is established: when treating melt with lead-base silumin in the low-temperature test interval, there is a slight increase in the linear expansion coefficient (LEC) at 100°C, compared with the initial one, to 8.210^-6, deg^-1. In the temperature range of 100-150°C LEC decreases to a minimum value of 7.210^-6, deg^-1. In the average temperature range of 150-300°C, a sharp, anomalous increase is noticeable, compared with the initial one up to 15.5210^-6, deg^-1. When studying the microstructure of cast iron after processing the melt with lead silumin, the formation of ledeburite structure is stated. Samples treated with lead-base silumin were subjected to cementation by feeding water steam at 900°C for 1-5 hours. It should be noted that, in the temperature range of 50-150°C, the values of the linear expansion coefficient lie almost in a straight line in the entire field of study. The coefficient varies from 10.810^-6, deg^-1 at 50°C to 13.710^-6, deg^-1 at 450°C. Preliminary heat treatment of cast iron in the carburizer made by the Bondyuzhsky plant with water steam smoothes anomalies of LEC and increases its initial values, and grinds perlite and cementite as well. Subsequent quenching in water with a temperature of 1000°C significantly changes the linear expansion coefficient of cast iron. Hardening of samples after cementation sharply reduces the linear expansion coefficient in the test range of 150-200°C, and in the temperature range of 350-450°C negative values of LEC are observed. Thus, it can be concluded, that treating the melt with lead-base silumin, cementation in the medium of the carburizer made by the Bondyuzhsky plant and subsequent hardening leads to sharp changes of the linear expansion coefficient up to negative values. The identified properties suggest the possibility of using cast iron where it is necessary to constancy of LEC and there are no requirements for the weight of the product.

Abstract: Effects of extrusion temperature and heat treatment process on the microstructure and mechanical properties of Ti-1300 titanium alloy tube billets were studied by tensile testing and microstructure observation, and the relationship among the thermal processing technique and microscopic structure and mechanical properties of the billets were also investigated. The results showed that the transverse structure of Ti-1300 alloy after extrusion in the a+b two-phase region was uniform and fine. And the longitudinal structure could be seen that the extrusion processing streamline was broken uniformly. Ti-1300 alloy extruded at a+b two-phase has a good match of the strength and ductility, and the ductility of two-phase extrusion is obviously better than that of β single-phase extrusion, especially for the reduction of area.

Abstract: The method to determine thermal fields considering dependence of thermophysical and mechanical properties of coating materials and a base from the temperature, the running of plastic deformations and stresses relaxation at plasma spraying is suggested. The mathematical model of calculation of thermal field with moving boundary considering nonlinear feature of coating growth at layer-by-layer deposition and dependences from thermophysical properties of materials of the system «coating-base» is developed. The model application helps to estimate the effect of the parameters of plasma spraying process on the level of the residual stresses in the increased coatings.