Journal of Thermal Analysis and Calorimetry最新文献

The thermal performance of natural-based composites remains a significant challenge in their industrial applications, especially in plat heat exchanger (PHE). This study aims to address this challenge by developing a bio-composite material using Green-epoxy biodegradable resin reinforced with banana fibre (Bn-GBC) and silicon carbide (SiC) as a filler, with the goal of improving its thermal conductivity and for fabrication PHE polymer biocomposite based. The study explores the effects of adding 2 mass% and 8 mass% SiC to the Bn-GBC, and an intumescent fire retardant (IFR) coating consisting of 29 mass% ammonium polyphosphate (APP) and 1 mass% boric acid was applied to the Bn-GBC/SiC samples. The manufacturing process involved the use of vacuum bag resin transfer moulding (VBRTM) technique. The study conducted Thermogravimetric analysis (TGA) tests under an O₂ atmosphere, with processing parameters such as temperature and variation in heating rates set at 303–1173 K and 5, 10, and 15 °C min⁻¹, respectively. The kinetic mechanism in the material was examined by calculating the kinetic parameters. The activation energy (E_a) was evaluated using model-free (the Friedman and KAS approaches) and fitting model of the Expanded Prout-Tompkins (Bna). In conclusion, all samples defined their kinetic parameter, the use of IFR reveals that increases E_a value by approximately 10–14%. TGA and cone calorimeter results indicated that the use of 8 mass% SiC improved the thermal stability of the composite compared to 2 mass% SiC. Moreover, from both thermal tests indicate that the application of a 16 mass% IFR (29Exolit/1BA) coating helped maintain the thermal stability and delay decomposition process. Thus, the PHE prototype was developed with 8 mass% SiC addition and without SiC addition. The Experimental and numerical heat assessment analysis was performed, it is proven that PHE/8SiC has a higher heat transfer compared to PHE/0SiC.

This study aims to investigative the relationship between the pore pressure and the explosive spalling of polypropylene (PP) fiber reinforced concrete when subjected to high temperature. Using the vapor pressure gauge, the moisture measuring sensor, and the thermocouple to measure the vapor pressure, moisture content, temperature, and the temperature on the heated surface of slab specimen, and observing the explosive spalling for the specimens of cylinder and slab made of PP fiber concrete. Test results showed that only the cylindrical specimen without PP fiber and 100% moisture content was apparently subjected to explosive spalling. Comparing with the test results of the slab specimen, the moisture content of the cylinder specimen had a significant effect on the occurring of explosive spalling. On the other hand, the effect of PP fiber on explosive spalling was obviously improved. The control slab specimen without fiber presented explosive spalling on the fire-exposed surface, causing the steel bar to be exposed to air, while the internal temperature rose faster than the PP fiber slab specimen without explosive spalling. The non- PP fiber slab specimen is affected by explosive spalling, the heat trend effect of temperature showed more obvious, and its moisture movement was more rapid than the slab specimen with PP fiber. Under similar moisture content, the slab specimen without PP fiber started sooner to explosive spalling with a serious explosive failure, on the contrary, the slab specimen with 0.1% PP fiber was completely without explosive spalling, indicating the significant effect of anti-explosive spalling by adding PP fiber in concrete.

This review discusses the development of the Derivatograph in the 1950s and the history of thermal analysis in Hungary. This device was the first commercial simultaneous thermogravimetry and differential thermal analysis (TG/DTA) instrument of the world. It initiated the development of thermal analysis and its application possibilities in a wide range during the second half of the last century. As a result, very strong thermoanalytical schools were established in Hungary, and the first thermoanalytical journal in the world, i.e., the Journal of Thermal Analysis was started in 1969, which is still a leading journal in the field, now under the title of Journal of Thermal Analysis and Calorimetry. In addition, several periodicals and books were published in thermal analysis in Hungary. In the paper, the most important Hungarian thermal analysis-related associations, events, acknowledgements and awards are also mentioned, together with names of major Hungarian researchers in this field. Presently, beside the internationally acknowledged research groups and the JTAC, the flagship of the Hungarian thermal analysis is the Journal of Thermal Analysis and Calorimetry Conference (JTACC) series.

The properties of coal fly ash vary significantly depending on factors such as coal type, combustion conditions, and flue gas emission reduction methods. This study investigates the influence of particle size fractionation on the chemical composition, mineralogical structure, and thermal behaviour of two types of fly ash: high calcium ash derived from lignite (S1) and silica-rich ash from bituminous coal (S2). Dry aerodynamic separation was used to obtain distinct size fractions, which were then subjected to a comprehensive characterisation including X-ray fluorescence, X-ray diffraction, scanning electron microscopy, and thermal analysis. The results reveal notable differences between the S1 and S2 ashes and between their size fractions. The finer fractions (< 20 μm) of S1 showed an increased calcium and sulphur content, while the coarser fractions (> 100 μm) contained more silica and alumina. The S2 ash exhibited a higher overall silica content, with alkali metals concentrated in finer fractions. Thermal analysis demonstrated distinct behaviours for each type and fraction of ash. Fine fractions of S1 ash showed SO₂ emission at elevated temperatures, while S2 ash exhibited greater CO₂ gas emission. After thermal treatment, the recrystallisation of the glassy phase was observed for S1, while the S2 ashes were more prone to melting and agglomeration. The study highlights the potential for the customised utilisation of specific ash fractions in various applications, such as geopolymer synthesis, adsorbent materials, and refractory products. This comprehensive characterisation contributes to a better understanding of fly ash properties and their dependence on particle size, providing valuable insights to optimise fly ash utilisation in various industries. The findings suggest strategies for a more efficient use of fly ash resources, particularly relevant in the context of decreasing fly ash availability due to the phase-out of coal power plants.

Five types of glass microspheres with alumina and 40–80 mol.% Y₃Al₅O₁₂ were prepared using solgel Pechini and flame synthesis techniques. Glass thermal behavior was analyzed using DSC/TG, XRD and SEM, and the JMAK model was applied to study crystallization kinetics and determine prevailing mechanisms. All samples, except the one with 80 mol.% YAG, had two exothermic effects in their DSC curves. The first appeared between 937 and 950 °C, while the second was observed between 958 and 1102 °C. XRD analysis of crystallized microspheres confirmed the presence of YAG and various forms of alumina phases in the samples with lower YAG/higher Al₂O₃ content (40 and 50 mol.%). The sample with the highest YAG content showed the strongest tendency to crystallize in the kinetics study. The value of apparent activation energy (E_app) of this sample was 987.3 ± 13.0 kJ mol⁻¹. For the remaining samples, the values of E_app were higher and ranged from 1215.1 ± 10.6 to 1847.5 ± 9.3 kJ mol⁻¹, indicating the lowest ability of these compositions to crystallization. The growth of three-dimensional (3-D) YAG crystals was predominant in glasses with the highest (80 mol.%) YAG content. One-dimensional (1-D) growth of γ-Al₂O₃ crystals and 3-D growth of YAG crystals was predominant in glasses with the lowest (40 mol.%) YAG content.