Effect Of Heating Rate Research Articles

The roles of heating rate, intensity, and duration on the response of corals and their endosymbiotic algae to thermal stress

Anthropogenic ocean warming is one of the biggest threats to marine organisms worldwide. However, it remains unclear how the duration and intensity of thermal anomalies affect organismal stress responses and thermal thresholds. We used detailed tracking of coral endosymbiont and host physiology and dose-response analyses to compare the effects of multiple heating rates, intensities, and exposure durations on two reef-building corals, Acropora hemprichii and Porites lobata, from adjacent sides of a reef (protected vs. exposed) in the Central Red Sea known to differ in high-frequency (< 24 h) temperature variability. Corals were exposed to acute heat exposures (18 h) with four target temperatures (32 °C, 35 °C, 36.5 °C, and 38 °C), versus prolonged heat exposures lasting 7–15 days where temperatures were raised 0.5 and 1.5 °C day−1 to four target temperatures (32 °C, 33.5 °C, 35 °C, and 36.5 °C). In the prolonged experiment, dose-response curves assessing algal endosymbiont Fv/Fm revealed little initial effect of temperature, before an exponential decline above 34 °C for both species. Temperature at time of measurement and degree heating hours above 34 °C (DHH34) were the variables most strongly associated with declines in Fv/Fm. The Fv/Fm thermal thresholds for P. lobata from the high-variability protected site were higher than the exposed site in the faster heating, prolonged heat stress experiment despite minimal differences in endosymbiont density, chlorophyll-a, and host protein between sites. Together, our dose-response analysis revealed complex effects of DHH34, heating rate, and species-specific differences in the influence of local thermal histories shaping thermotolerance limits for these corals.

Study on the mechanical strength and iodine adsorption behavior of coal-based activated carbon based on orthogonal experiments

To prepare coal-based activated carbon with high mechanical strength and adsorption performance for the removal of iodine from wastewater, the effects of carbonization temperature, heating rate, activation time and activator on the mechanical strength of activated carbon were studied; the optimal production conditions were determined by comprehensively considering the specific surface area, iodine value, compressive strength and wear resistance based on previous studies. Iodine adsorption kinetics and equilibrium adsorption experiments were carried out on activated carbon prepared under the optimum conditions. The results showed that the increase in mechanical strength was caused by the release of volatile matter and secondary reactions, which formed the carbon skeleton, while the decrease in mechanical strength was due to the intervention of the activator, which destroyed the carbon skeleton. The adsorption kinetics showed that a pseudo-second order kinetic model was more suitable for the adsorption behavior of iodine on activated carbon. The equilibrium adsorption experiment results showed that iodine was evenly adsorbed on the surface of activated carbon, and with increasing temperature, the affinity of the active sites of activated carbon to iodine also increased.

Fast co-pyrolysis behaviors and synergistic effects of corn stover and polyethylene via rapid infrared heating

Rapid infrared heating with fast heating rates and the capacity to load materials on the gram scale help investigate the co-pyrolysis behaviors, minimizing the gap of materials’ pyrolysis temperature and volatile release during the co-pyrolysis. This work explored the effects of temperature and heating rate on the co-pyrolysis product s behaviors and synergistic interactions of corn stove and polyethylene. Initial increases in oil yield were followed by decreases when the heating rate rose, and when the temperature increased from 500 °C to 600 °C, the oil yield rose from 17.91 wt% to 20.58 wt% before falling to 14.75 wt% at 800 °C. High heating rate promoted the oil generation, and the maximum oil yield was at 25 °C/s with varying heating rates from 15 °C/s to 35 °C/s. The pyrolysis gas produced at 25 °C/s exhibited the highest LHV (Low heating value) and lowest CO2 yield, which were 17.23 MJ/nm3 and 39.29 vol%, respectively. The suitability of heating rate and temperature may improve the interaction between H-radicals of PE and oxygenated groups of CS to generate stable macromolecular compound and enhance oil production. GC–MS studies of the oil products demonstrated that oxygenated compounds such as furans, phenols and acids from lignocellulosic depolymerization had been converted to high molecular weight long chain alcohols (mostly C26, C20 and C14 alcohols) via stronger interactions during fast infrared-heated co-pyrolysis. The alcohols increased from 32.29 % to 65.06 % as temperatures rose from 500 °C to 800 °C. Few furan heterocycles, acids and phenols were detected, suggesting that the oil presented higher quality and stronger synergistic effects. Rapid infrared heating accelerated the synergistic effects between volatile-volatile interactions during co-pyrolysis of corn stover and polyethylene, and the increases in temperature and heating rates further enhanced the release of many volatile substances and the formation of fine pores. Raman results showed char of 600 °C deposited more pure aromatic structures, the influence of temperature on aromatization was stronger than that of heating rate.

Dependence of CZTS thin film properties and photovoltaic performance on heating rate and sulfurization time

In this study, effect of heating rate and sulfurization time on the properties of CZTS thin films and their photovoltaic performances was investigated. CZTS layers were prepared by a two-stage technique comprising deposition of precursor films by sputtering on Mo-foil substrates (Mo-foil/ZnS/CuSn/Cu) and a sulfurization process utilizing Rapid Thermal Annealing (RTA) approach. Heating rates and sulfurization times at 550 °C were changed to determine the best conditions. CZTS films were characterized by several techniques. All samples showed Cu-poor and Zn-rich chemical composition regardless of the heating rate and annealing time of the sulfurization process. XRD diffraction patterns showed that only kesterite CZTS phase was formed in all samples. Although Raman spectroscopy measurements confirmed formation of kesterite CZTS phase in all samples, forming of Cu2SnS3 (CTS) secondary phase was detected in all films except for the sample prepared utilizing a relatively low heating rate of 1 °C/s and 60 s sulfurization time (CZTS-I-60). The largest crystallite size and the less micro strain and dislocation density were also found in this sample. All CZTS thin films displayed dense and compact polycrystalline surface microstructure. Optical characterizations showed that the optical band gaps of the films were in the range of 1.48–1.58 eV. PL emission spectra of the films exhibited transition from conduction band to acceptor/defect levels instead of band-to-band transition. Solar cells were fabricated and the highest Voc and conversion efficiency (4.39%) were achieved employing the film obtained with ramp rate of 1 °C/s and the sulfurization time of 60 s, because of better structural properties and purer crystal structure determined for this sample.

The orientation dependence of stored energy and the evolution of texture of through-thickness tantalum targets during heating

In semiconductor integrated circuits, the orientation dependence of the stored energy and texture distribution uniformity of sputtering tantalum targets are critical to the properties of the deposited films which block the diffusion of Cu atoms into the storage cell Si. In this paper, the effect of heating rate on the recrystallization behavior was investigated with the aid of a differential scanning calorimeter (DSC). In addition, the texture and stored energy of deformed tantalum targets with different heat treatments along the thickness direction were characterized using electron backscatter diffraction (EBSD). The results show that the initial temperature of recrystallization rises but the temperature range reduces with the increase of the heating rates. The stored energy of deformed tantalum targets presents various orientation dependencies in different thickness layers. During the heating process, the stored energy difference among the grains with different orientations decreases, but the maximum difference of stored energy in different thicknesses increases inversely. The content of {101} oriented grains increases as the temperature increases, while the content changes of {111} and {001} present a waveform with an opposite trend.

Microscale failure analysis of the ultra-high-performance polypropylene fibre reinforced concrete panel subjected to high thermal loading induced by fire exposure

To date, many buildings are prone to fire from non-structure systems like high-pressure laminates and insulated cladding systems. Ultra-high-performance concrete (UHPC) has been applied to the cladding systems due to its excellent mechanical properties at room temperature and non-flammable characteristic. To improve its mechanical properties under fire condition, different fibres like PP fibre have been employed to reinforce UHPC. The tensile strengths of these ultra-high-performance PP fibre reinforced concrete (UHPPFRC) panels vary due to the different orientations of internal PP fibres. However, few studies have been carried out on the internal stress and fire resistance of these claddings. Study on understanding the fire behaviours and failure process of the UHPPFRC panel is essential for developing claddings with better fire resistance and durability. In this study, a coupled hygro-thermal–mechanical model is developed to predict the internal stress and temperature distribution within the UHPPFRC panel. The microscopic failure process of PP fibre and porosity change within the panel during heating are all embodied in the model, and its accuracy has been validated. The initial and the residual tensile strengths of the UHPPFRC panel are considered to fluctuate between two extrema due to the random fiber orientation. Based on this, Program Evaluation and Review Technique (PERT) is applied to investigate the effects of fibre dosage and heating rate on retarding crack propagation and failure of the UHPPFRC panel under high temperature. Results from the numerical investigation indicate that 0.55% dosage of PP fibre can effectively postpone crack occurrence and propagation within the UHPPFRC panel at linear elastic phase, and faster heating rate can accelerate the pore pressure generation process. Also, internal fibre orientation is a significant factor affecting the fire endurance of the UHPPFRC panel subjected to elevated temperature, which should be considered for safety and reliability evaluation of the structure.

Heating rate and ZSM-5 catalyst effects on date palm (Phœnix dactylifera L.) stones pyrolysis: Thermogravimetric analysis, production and characterization of syngases and bio-oils

In the present investigation, Date palm stones (DPS) were pyrolyzed under Nitrogen atmosphere in a laboratory scale fixed-bed reactor. Pyrolysis experiments were carried out at different heating rates (5 and 10 °C/min), both in absence and presence of ZSM-5 catalyst (20 wt%). The effects of heating rate and ZSM-5 catalyst on DPS thermal behavior, pyrolysis products yields, syngases and bio-oils proprieties were investigated. TGA results showed that adding ZSM-5 revealed no significant impact on DPS thermal behavior. However, increasing the heating rate was followed by an increase in degradation peaks temperatures and maximum mass-loss rates (in absolute terms). These same effects were found when proceeding in presence of ZSM-5. Micro-GC results showed that the heating rate rise led to a thermal shift of pyrolytic gases (CO2, CO, C2H6, CH4 and H2) release towards higher temperatures. However, the ZSM-5 addition had accelerated their release and enhanced their quality by essentially reducing CO2 contents by about 13%, for both heating rates. The produced syngases from DPS pyrolysis have proven good biofuels proprieties thanks to their important proportions of CH4 (17.19–21.74%) and H2 (12.54–18.51%). DPS pyrolysis at a heating rate of 5 °C/min and in presence of ZSM-5 (20 wt%) can be defined as the optimum operational conditions that lead to maximum production of bio-oil (43.48%) with better quality. Under these conditions, DPS bio-oil presented the highest Carbon (73.58%) and Hydrogen (10.63%) contents and the lowest Oxygen (14.89%) and Nitrogen (0.9%) contents. Moreover, it had the highest HHV of 34.37 MJ/kg and the lowest viscosity of 8.54 mPa s, comparing to other bio-oils produced at 10 °C/min with and without ZSM-5 and to the bio-oil produced at 5 °C/min without ZSM-5. GC-MS analysis revealed that Dodecanoic acid and Oleic acid were the predominant components in DPS bio-oil with the respective percentages of 17.83 and 16.49%. This experimental investigation proved the potential use of date palm stones as renewable feedstocks for bio-oil production by pyrolysis. Furthermore, the low pyrolysis gradient (5 °C/min) and the use of ZSM-5 catalyst have shown interesting results in enhancing the bio-oil quantity and quality.

Slow heating rates increase thermal tolerance and alter mRNA HSP expression in juvenile white sturgeon (Acipenser transmontanus)

Freshwater fish such as white sturgeon (Acipenser transmontanus) are particularly vulnerable to the effects of anthropogenically induced global warming. Critical thermal maximum tests (CTmax) are often conducted to provide insight into the impacts of changing temperatures; however, little is known about how the rate of temperature increase in these assays affects thermal tolerance. To assess the effect of heating rate (0.3 °C/min, 0.03 °C/min, 0.003 °C/min) we measured thermal tolerance, somatic indices, and gill Hsp mRNA expression. Contrary to what has been observed in most other fish species, white sturgeon thermal tolerance was highest at the slowest heating rate of 0.003 °C/min (34.2 °C, and CTmax of 31.3 and 29.2 °C, for rates 0.03 and 0.3 °C/min, respectively) suggesting an ability to rapidly acclimate to slowly increasing temperatures. Hepatosomatic index decreased in all heating rates relative to control fish, indicative of the metabolic costs of thermal stress. At the transcriptional level, slower heating rates resulted in higher gill mRNA expression of Hsp90a, Hsp90b, and Hsp70. Hsp70 mRNA expression was increased in all heating rates relative to controls, whereas expression of Hsp90a and Hsp90b mRNA only increased in the two slower trials. Together these data indicate that white sturgeon have a very plastic thermal response, which is likely energetically costly to induce. Acute temperature changes may be more detrimental to sturgeon as they struggle to acclimate to rapid changes in their environment, however under slower warming rates they demonstrate strong thermal plasticity to warming.

INFLUENCE OF HEATING RATE ON THE STRUCTURAL AND OPTICAL PROPERTIES OF SILVER AND GERMANIUM CO-DOPED CZTS THIN FILM

The effect of heating rate on the structural and optical properties of Ag+Ge co-doped CZTS thin film were investigated and compared with the undoped CZTS sample. The undoped and Ag+Ge co-doped CZTS samples obtained by two-stage technique consisting of the sequential deposition of the precursor stacks by sputtering systemand sulfurization of these layers at elevated temperature in the RTP system by employing heating rate of 1°C/s, 2°C/s and 3°C/s. Ag and Ge co-doped precursor stack as well as undoped stack demonstrated Cu-poor, Zn-rich composition. In addition, the dopant ratio of the Ag+Ge co-doped stack was close to the targeted content considering to EDS measurement. Regardless of the employed heating rate or the doping process, all of the samples crystallized in a kesterite structure. However, it was confirmed by XRD measurements that high heating rates caused phase separation in kesterite phase formation. On the other hand, The Raman peaks assigned to Cu-vacancy and CuZn antisite defects formation inhibited with incorporating Ag and Ge into the CZTS structure. Ag and Ge co-doped CZTS sample produced with a heating ramp rate of 1°C/s showed better structural and optical results among them.

Investigation of intumescent coating on the fire endurance of concrete-filled steel columns with varied characteristics

Concrete-filled steel columns (CFSC) are becoming increasingly popular in contemporary construction, particularly for the construction of tall buildings and structures with large spans. These columns offer superior fire protection compared to concrete or steel-only columns. Furthermore, CFSCs offer significant structural benefits by enhancing properties such as high tensile and compressive strength, ductility, capacity for energy absorption, improved fire resistance, and thermal insulation. However, there remains a notable research gap pertaining to the comprehensive analysis of the temperature distribution in CFSC sections that are protected by intumescent fire coating (IFC). Particularly, there is a need to investigate the specific effects of various heating rates, intumescent coating thickness, and steel thickness on the temperature distribution within these sections. The current research involved the creation of a finite element model for analyzing heat transfer and fire resistance in columns. This model was used to examine how the columns would perform under different fire conditions, including Standard (ISO-834), Fast, Slow, and Smouldering fires. The model has been verified with the available literature. Core concrete, dry film thickness (DFT) of intumescent coating, and steel section thickness are the primary determinants of the temperature rise of the protected CFSC section under fire considered in the developed models. This study adds large-scale column specimens to the corresponding numerical database. The numerical results provide additional proof that a CFSCs coated with an intumescent fire coating can achieve high fire resistance. With efficient IFC insulation and core concrete heat absorption, the temperature increase of a CFSC can be greatly retarded.

Effects of heating rate and shell colour on the cardiac thermal performance in a polymorphic gastropod Batillaria attramentaria

Heating rate has gained extensive attention in mechanistic understanding of physiological responses to changing thermal conditions in the context of climate change. In polymorphic gastropods, differences in the absorption of solar energy between dark- and light-coloured individuals lead to supposable differences in their heating rates and body temperatures in sunshine. In the present study, we examined the effect of heating rate on heart rate (HR) in a polymorphic gastropod Batillaria attramentaria. By using biomimetic models, we found that daily maximum temperature of snails with a dark unbanded shell (D-type morph) was higher than snails with a white line on the upper side of each whorl (UL-type morph) by 0.6 °C when exposed to sunlight, but there was no apparent difference in heating rates between D- and UL-type models. We measured HR of snails at various heating rates from 3.0 to 9.0 °C h−1. Faster heating rates significantly increased maximum thermal tolerance in both D- and UL-type snails, highlighting the importance to have thorough knowledge on the heating rate in the field to obtain accurate maximum thermal limit of gastropods. Critical temperature at which HR precipitously declines was higher in D-type snails than UL-type snails. Our results suggested that the impacts of heating rate as well as the shell colour should be considered to gain a mechanistic understanding of the population dynamics of polymorphic gastropods.

Study on the mechanism of catalytic fast co-pyrolysis of biomass and coal tar asphaltenes: Gas-liquid-solid products' optimization

It is very important to evaluate how coal tar asphaltenes (CTA) and corn cob (CB) could be used comprehensively in order to achieve zero waste. Catalytic co-pyrolysis is a feasible method to reduce CO2 emissions, realizing the development and utilization of biomass energy, and the recycling of asphaltenes. In this study, the catalytic effect of K on co-pyrolysis was more obvious than that of Ca, Co, Ni, Cu and Zn based on the analysis of TG/DTG, FTIR and Py-GC/MS. The response surface design method and artificial neural network were introduced to comprehensively investigate the effects of mixing ratios, metal loads and heating rates on the catalytic co-pyrolysis. The results showed that K-catalysis co-pyrolysis effectively improved the yield of gas and char, and increased the content of phenolics. In particular, when the load of K was 5.3 wt%, the heating rate was 476 °C/min, and the proportion of CB was 38 wt%, the maximum solid yield was 35.16 wt%, and the solid product had good catalytic ability. Based on the above analysis, the mechanism of K-catalysis co-pyrolysis was proposed.

Investigation of stress relief crack susceptibility of CrMoV steels coarse grain HAZ via simulation of uniaxial stress conditions during PWHT

Creep-resistant steels such as the 13CrMoV9-10, used in the construction of thick-walled pressure vessels, are most commonly submerged arc welded (SAW). These steels can develop stress relief cracks (SRC) if the mandatory post weld heat treatment (PWHT) is performed improperly. Current PWHT parameters, such as heating rate and holding time at a specific holding temperature, are based on both empirical experience and conventional free shrinking welding experiments to characterize the SRC-susceptibility of the weld. These cannot adequately depict the higher residual stresses caused by the structurally induced stiffness of the surrounding construction.This study discusses the development of a repeatable, precise, and time-efficient methodology to study the effects of different stress levels and heating rates on the SRC susceptibility of the coarse grain heat-affected zone (CGHAZ). For that purpose, samples were thermically treated to simulate a coarse grain heat-affected zone (CGHAZ) and subsequently exposed to representative levels of stress during the heating phase of a PWHT. The recorded stress and heating rate–dependent strains were mathematically analyzed via curve tracing/calculus to identify interdependent effects. This procedure facilitates the measurement of material characteristics such as carbide growth on grain boundaries at the µm-scale via an integrated value over the entire sample volume. The first and second derivatives show a slight, precipitate-dependent, increase in hardness of the sample, depending on the heating rate and applied stress. This new methodology generates an improved assessment of the SRC susceptibility of SAW microstructures of creep-resistant CrMoV steels.

Mechanism of sulfur migration and conversion in pyrolysis/combustion staged conversion process of high sulfur coal

To investigate the effects of circulating ash heat carriers and dolomite catalysts on sulfur migration in the coal pyrolysis/circulating fluidized bed combustion staged conversion process, five experiments of coal pyrolysis, ash/coal co-pyrolysis, coal pyrolysis catalyzed by dolomite, ash/coal co-pyrolysis catalyzed by dolomite and combustion of pyrolysis solid products were designed and carried out. By examining the effects of pyrolysis temperature, heating rate, coal-ash ratio and dolomite species on sulfur migration, the final distribution of sulfur-containing pollutants throughout the staged conversion process was systematically analyzed. The results showed that the separate mixing of ash heat carrier at final pyrolysis temperature of 600 °C increased the residual sulfur in solid phase from 79.29 % of raw coal pyrolysis to 90.00 %. When dolomite catalyst was added individually, the sulfur released into gas phase and tar was reduced from 18.28 % and 2.43 % of the raw coal to 13.14 % and 1.94 %, respectively. And Fe additive significantly improved sulfur resistance of the dolomite catalyst. The regeneration process has little effect on the sulfur fixation capacity of natural dolomite. When ash heat carrier and dolomite catalyst were simultaneously added to the system, the sulfur fixed in ash increased from 79.29 % of the raw coal to 91.27 %, and the sulfur fixed in natural dolomite and modified dolomite accounted for 4.32 % and 4.46 % of the total sulfur, respectively. In the combustion experiments of pyrolysis solid phase products, 43.57 %, 65.57 % and 61.44 % of sulfur was retained in the solid phase residue after combustion with circulating ash, circulating ash/natural dolomite and circulating ash/modified dolomite were added, respectively. Compared with direct combustion of coal, the staged conversion process resulted in a 55 % reduction of sulfur in the boiler flue gas. This study provides a theoretical basis for the purification of sulfur-containing pollutants in the staged conversion process.

Investigation on the mechanism of heating effect influencing emulsifying ability of crude oil: Experimental and molecular dynamics simulation

Water flooding can create a transient heating effect that causes oil and water to self-emulsify. This study sought to understand how this effect impacts crude oil's emulsifying properties by conducting oil-water emulsification experiments and investigating the effects of initial temperature, heating rate, and effective time. Additionally, asphaltene dispersion, adsorption behavior, and viscoelasticity of crude oil and its interfacial components were analyzed to unravel the mechanism behind the heating effect on crude oil's emulsifying capacity. The heating effect was observed to suppress interaction force dissipation between asphaltene molecules effectively from low to high temperatures. This increased both the interfacial film thickness and steric hindrance, improving crude oil's emulsifying ability. However, at high temperatures, the interfacial film became unstable, which led to the normalization of crude oil's emulsifying ability after the effective time. These findings provide insight into the emulsifying mechanisms of water-drive reservoirs and the in-situ emulsifying theory of underground crude oil.

Analysis of residual stress relief for Ti62A alloy welded joints by post weld heat treatment considering creep effect

In this paper, the Arrhenius-type constitutive equation based on strain compensation was developed, and the constants of the constitutive equation were determined by linear fitting to construct the material models of Ti62A alloy. Meanwhile, the creep parameters of Ti62A alloy at high temperature were corrected by existing experiments, and the Norton creep model during post weld heat treatment (PWHT) was established. The sequential coupling finite element method was used to calculate the residual stress distribution in the welding and PWHT processes of Ti62A alloy plates. The effects of PWHT parameters on the residual stress relief of welded joints were revealed, such as creep, heating rate, and heat treatment temperature. The results reveal that the creep has an important influence on residual stress relief during PWHT. Compared with longitudinal residual stress, the effects of heating rate and heat treatment temperature on transverse residual stress are more significant. A lower heating rate or higher heat treatment temperature will be beneficial for releasing residual stress. The results of this paper will contribute to a better understanding of PWHT mechanisms and provide a good theoretical guidance for optimizing process parameters.

Thermoluminescence properties of TiO2/Cu/TiO2 multilayer thin films fabricated by (RF/DC) sputtering for radiation dosimetry

The most popular TLDs are composed of phosphors, ceramics, and crystals. Despite having a high light output per unit of absorbed dose, they suffer from rapid signal fading, light scattering, saturation at higher doses, and difficulties annealing for re-use. Here, we report the characteristics of a novel TiO2/Cu/TiO2 multilayer thin film dosimeter fabricated using radio-frequency (RF) and direct current (DC) sputtering methods with a faster deposition rate, high purity, and uniformity. The multilayer sequence was set to TiO2 (150 nm)/Cu (x)/TiO2 (50 nm), at varying Cu thicknesses (x = 5, 10, 25, 40, and 50 nm). The structure, morphology, elemental composition, and optical properties of the films were characterized by the XRD, FESEM, EDX, and UV–Vis, respectively. Next, the best TiO2 multilayer films with 5 nm Cu were tested for morphological, structural, and optical properties at 600 and 1200 mGy of x-ray radiation. The dosimetric properties of samples irradiated with X-ray doses ranging from 100 to 1500 mGy were then investigated. The best annealing time, reproducibility, fading, low minimum detectable dose as well as the effect of different heating rates on the TL glow curve have all been studied. Our results indicate that the films are amorphous, porous with spherically shaped nanoparticles, have a uniform distribution of elements, and are transparent in the visible region. The optimum TL intensity was found at TiO2 (445 nm)/14.2 nm Cu/TiO2 (130 nm) sequence. The dose-response has a good linear correlation to x-ray radiation with a sensitivity that is 0.444 times less than that of TLD-100 sensitivity within the dose range 100–1500 mGy. Upon irradiation, the band gap decreases, crystallinity increases, pores increase, films become rougher, and the absorption band edge extends to higher wavelengths. The single and multilayer TiO2 films have high-intensity peaks at 270 and 274 ∘C, respectively, which is typical of TL glow curve peaks used in TLD applications. There were no significant changes in the TL reading after six times of reuse, and the fading was observed at 49.57% after 15 days of irradiation. The findings indicate that TiO2/Cu/TiO2 multilayer films are appropriate for thermoluminescence dosimetric applications.

The influence of heat rate and austenitization temperature on microstructure and hardness of Hadfield steel

The As-Cast condition of Hadfield alloy usually contains (Fe, Mn)3C carbides around the austenitic grains, which promote brittleness, making the steel impractical in industry. Heat treatment is normally applied to reduce carbide content, lower carbides, and improve toughness. However, a complete austenitic structure is not attainable during solution treatment. The dissolution temperature and dissolution time are critical to obtaining complete carbide content. Furthermore, heating must be done slowly, and the quenching speed must be fast enough. This study examines the effect of heat rate and austenitization temperatures in the solution treatment on the microstructure and hardness of Hadfield steel. The heat rate of 3, 6 and 10 oC/min is selected to determine whether there is a change in the microstructure of Hadfield steel. The four austenitization temperatures of 1000, 1100, 1150 and 1200 oC are used to ascertain carbide dissolution into the austenite matrix. Grain boundary, hardness, and phase transformation will confirm the microstructural change and hardness properties. The optical microscope shows carbide content is reduced as the austenitization temperature increases. The consequence of carbide dissolution affects the hardness. Its hardness decreases as temperature increase due to the loss of carbide. The as-Cast specimen has the highest hardness of 227.8 HV30, and the lowest hardness is 176.7 HV30 belongs to a specimen that is heated up to 1200 °C and quenched into water. Grain size is measured by the line intercept method, which shows its increase as temperatures increase. The result of grain measurement is as follows: As-Cast 224.6 mm, T 1000 °C 323.3 mm, T1100 °C 409.2 mm, T1150 °C 1014.4 mm, T1200 °C 881.6 mm. SEM-EDS confirms that the main phase is austenite, and a small amount of carbide is detected in the austenite matrix.

Fabrication of an atomically smooth Ge(111) surface by Au-induced crystallization at 170 °C

Crystalline Ge layer fabricated via layer-exchange metal-induced crystallization is a promising candidate as a seed layer for the epitaxial growth of III–V semiconductor thin films for multijunction solar cells. However, small crystalline islands that grow on top of the crystalline Ge layer are a problem, which roughens the surface and hinders subsequent epitaxial growth. Considering the effect of heating rate on the Au-induced crystallization behavior of Ge, it is found that the temperature required for the island growth in the top Ge layer was higher than that for the bottom layer. By carefully choosing the annealing conditions, the growth of the top Ge layer can be avoided resulting in an atomically smooth Ge(111) surface.

Study on the molecular structure model of tar-rich coal and its pyrolysis process

With the continuous consumption of medium/high-rank coal and increasing energy shortage, the conversion and utilization of low-rank coal is gaining attention. A rational molecular model of coal combined with reaction molecular dynamics (ReaxFF MD) is becoming a promising way to explore coal conversion processes at the molecular level. In this work, a molecular structure model of tar-rich coal from northern Shaanxi, China, with the molecular formula C355H332O57N4S was proposed by combining experimental characterization tests and theoretical computational analysis. In addition, the molecular model was validated by calculating FTIR and 13C NMR spectra with quantum chemistry. Furthermore, complex multi-molecule systems were constructed based on the single-molecule model, the effect of heating rates on the pyrolysis process was investigated by ReaxFF MD simulations, and the evolution of pyrolysis process and products were analyzed in detail. The results show that a slower heating rate helps to obtain more gas products, inhibit the condensation reaction between tar fragments, and promote their cracking, more light tars could be obtained. The combination of experimental characterization and theoretical calculations provides a comprehensive understanding of the molecular structure and pyrolysis processes of tar-rich coal, and provides a basis for an in-depth study of the structure of low-rank coal and its clean utilization technologies.