Processing Temperature Research Articles

Evolution of Cu-rich particles and Laves phases in a novel Cu-alloyed martensitic heat-resistant steel during interrupted creep and the corresponding effects on microstructural recovery

Cu-alloyed martensitic heat-resistant steels are considered promising structural materials in advanced ultra-supercritical (USC) plants. In this work, the evolution of Cu-rich particles (CRPs) and Laves phases (LPs) in the G115 steel and the corresponding effects on microstructure recovery were systematically studied via interrupted creep. Most CRPs precipitated within the lath interior during tempering process and started to precipitate along the lath boundaries during creep. The interior-precipitated CRPs were gradually decomposed due to dislocation cutting effect, resulting in the decrease of their number density. The precipitation of CRPs along the lath boundaries could induce the heterogeneous precipitation of LPs owing to the decrease of nucleation barrier. The number density of LPs rapidly increased during the transient stage but started to decrease during the steady-stage stage due to the coarsening behaviors of Ostwald ripening and swallowing adjacent M23C6 particles. The larger size and decreased number density of LPs and CRPs considerably weakened their pinning force for dislocations and boundaries, leading to an intense microstructure recovery during the accelerated stage. Eventually, the large area of recrystallized grains and subgrains with low hardness and the accumulation of cavities resulted in the creep fracture.

Możliwość produkcji materiałów wtórnych z odpadów węglowodorowych

The utilisation and processing of crude oil sludge is one of the major global challenges. Therefore, it is necessary to justify the following scientific solutions in the field of oil sludge utilisation and processing worldwide: the study of the physicochemical properties of oil sludge in order to obtain construction grade bitumen; detection of dispersion of solid particles in the composition of oil sludge; development of the optimal technological parameters for the process of obtaining construction grade bitumen from oil sludge; establishing a correlation dependence between process efficiency and the environment, the content of light fractions in the sludge composition, the process temperature. In this work, oil sludge was diluted with a solvent in a ratio of 70:30, with light naphtha used as a solvent. A laboratory distillation column was used to separate the sludge into fractions, and the chemical composition of the oil sludge was investigated. Oil sludge consists of asphaltenes up to 4.2–4.5%, resins up to 21.0%; paraffin-naphthenic hydrocarbons up to 41.2%; monocyclic aromatic hydrocarbons up to 4.6%; bi- and tricyclic aromatic hydrocarbons up to 5.8%; polycyclic aromatic hydrocarbons up to 9.7%. The paper also presents the results of the change in the viscosity and density of the distillate fractions separated during the distillation of diluted oil sludge. Density and viscosity were measured using an areometer and a VPZh-4, respectively. One of the main components of the oil sludge is water. A series of experiments were conducted to determine the water content using the Dean and Stark method. In addition, the sulphur content in oil sludge diluted with solvents – light and heavy naphtha, heavy gas oil – was determined.

The influence of V microalloying on the hot deformation behavior and microstructure evolution of high-manganese steel for LNG storage tanks.

Herein, the high-temperature hot deformation and dynamic recrystallization (DRX) behavior of high-manganese steel were investigated through the measurement of true stress-strain curves, the establishment of constitutive equations, the construction of recrystallization and hot processing maps, and the characterization of microstructure evolution. Furthermore, the influence of V on the DRX behavior of high-manganese steel during the hot deformation process, particularly for LNG storage tanks, was systematically evaluated. The results indicate that both the critical stress (σc) and peak stress (σp) of the tested steels increase as the deformation temperature decreases and the strain rate increases. Additionally, a higher V content leads to an increase in σc and σp, thereby suppressing the occurrence of DRX. Compared to 0.1V steel, 0.2V steel precipitates a greater quantity of carbides at the grain boundaries (GBs), which effectively stabilizes the GBs and inhibits the growth of DRX grains. In contrast, 0.1V steel achieves DRX over a wider range of Z parameters (at lower temperatures and higher strain rates). The activation energies for hot deformation (Q) of the two tested steels are 479.100 kJ/mol and 438.274 kJ/mol, respectively. The hot processing maps indicate that an increase in V content reduces the hot workability of high-manganese steel. The optimal temperature and strain rate for hot processing of 0.1V steel are 1035–1095°C and 0.01–0.0451 s⁻1, respectively. For 0.2V steel, the optimal hot processing parameters are a temperature of 1065–1100°C and a strain rate of 0.01–0.07 s⁻1.

Innovative design and process simulation of aviation bracket based on topology optimization and additive manufacturing

Abstract In this paper, topology optimization(TO) and laser powder bed fusion (LPBF) technology were combined to explore the key technology of parts integration design and manufacturing oriented to performance, structure and manufacturing process. With the help of topology optimization(TO), the lightweight design of the aviation bracket achieved the weight loss goal of 87.69% in this work. The thermophysical properties of TC4 were calculated by thermodynamic calculation, and the temperatue interval of Laser Powder Bed Fusion for TC4 is 1800 °C−3000 °C was determined . Additionally, the LPBF macro-scale simulation was carried out. The results showed that the maximum temperature in the printing process is lower than 2500 °C, and the maximum displacement is 4.87 mm, which only appears in the non-design space. Finally, the safety factor and maximum displacement of aviation bracket are 1.2 and 0.8 mm, and the maximum Mises stress is 685 MPa, all of which meet the design requirements.

Comparison of measured and calculated high-viscosity crude oil temperature values in a pipeline during continuous pumping and shutdown modes

The paper investigates the stationary and non-stationary cooling processes of high-viscosity crude oil temperature in the Severnye Buzachi – Karazhanbas pipeline during both pump operations and pump shutdowns. To transport high-viscosity crude oil through pipelines, the hot pumping method is employed. During oil transportation and pump shutdowns, the oil temperature decreases due to heat exchange with the environment, leading to an increase in oil viscosity. As viscosity rises, more power is required from the pumps to move the thickened oil, resulting in higher electricity consumption. To avoid increased operational costs after pump shutdowns, it is crucial to accurately calculate the oil cooling temperature in order to determine the safe shutdown duration and a critical temperature threshold. The Shukhov formula is used to calculate oil temperature during transportation, while a modified version is applied during pump shutdowns. To verify the accuracy of the obtained oil temperature results, the calculated values were compared with the measured values from pipeline sensors in both stationary and non-stationary cases. The novelty of the work is in determining the methodology for calculating the safe shutdown time of a pipeline for high-viscosity oil. The proposed formula was validated using experimental data from SCADA system sensors in real-time.

Zn-phosphate conversion coatings developed on high-strength steels at reduced processing temperature

The effect of process time, ultrasonic stirring, and the addition of H2PO4- on the morphology and corrosion resistance of phosphate conversion coatings was investigated by Scanning Electron Microscopy and electrochemical tests. The phosphating treatments were performed at 50 °C, lower than traditional processes, and pH 2.9 and 2.4. An enhanced film of bigger mass and reduced corrosion rate was produced when the processing time was extended from 6 to 30 min. at pH 2.9. No important changes were identified in the appearance other than a slight crystal coarsening and Zn enrichment. Both the ultrasonic stirring and the addition of H2PO4- (pH 2.9, 6 min.) accelerate the coating formation rate and assist in the formation of more uniform layers with a greater Zn concentration. An important crystal refinement was also obtained in the ultrasound-induced treatment, whereas no relevant changes were found for the corrosion behaviour. The addition of H2PO4- in the amount of 10 g/L (pH 2.9, 6 min.) facilitates the formation of a layer with a quality like that found in the longest treatment (30 min.). None of the tested variables provided an effective modification to improve the performance of the conversion layers developed for the baths considered in this study at pH 2.4.

Hypoeutectic Liquid Metal Printing of 2D Indium Gallium Oxide Transistors.

2D native surface oxides formed on low melting temperature metals such as indium and gallium offer unique opportunities for fabricating high-performance flexible electronics and optoelectronics based on a new class of liquid metal printing (LMP). An inherent property of these Cabrera-Mott 2D oxides is their suboxide nature (e.g., In2O3-x), which leads high mobility LMP semiconductors to exhibit high electron concentrations (ne >1019cm-3) limiting electrostatic control. Binary alloying of the molten precursor can produce doped, ternary metal oxides such as In-X-O with enhanced electronic performance and greater bias-stress stability, though this approach demands a deeper understanding of the native oxides of alloys. This work presents an approach for hypoeutectic rapid LMP of crystalline InGaOx (IGO) at ultralow process temperatures (180°C) beyond the state of the art to fabricate transistors with 10X steeper subthreshold slope and high mobility (≈18cm2Vs-1). Detailed characterization of IGO crystallinity, composition, and morphology, as well as measurements of its electronic density of states (DOS), show the impact of Ga-doping and reveal the limits of doping induced amorphization from hypoeutectic precursors. The ultralow process temperatures and compatibility with high-k Al2O3 dielectrics shown here indicate potential for 2D IGO to drive low-power flexible transparent electronics.

Co-calcination to produce a synergistic blend of bauxite residue and low-grade kaolinitic clay for use as a supplementary cementitious material

New sources of reactive supplementary cementitious materials (SCMs) are essential to help the cement industry to further lower CO2 emissions. A co-calcination process in which bauxite residue (BR) is mixed with kaolinitic clay before calcination can deliver such SCM. The main novelty of the work discussed here is that acceptable reactivity as a SCM can be reached when co-calcining the BR with clays having only 40 wt% of kaolinite. The use of such low-grade kaolinitic clay greater increases the process economics and therefore likely increases overall feasibility. A high inherent reactivity of the desilication products present in the BR is the cause of this ability of using low-grade kaolinitic clays. Cement mortars were made with 30 wt% replacement of CEM I, which showed adequate strength at 28 days and increased strength in comparison with calcined clays or other SCMs in the literature at early age (2–7 days). A wide process temperature window with relatively constant reactivity was observed, but a range of 700–750 °C is recommended for process stability. In addition, a life-cycle assessment underlines that at these conditions a sufficiently low embodied CO2 relative to Portland clinker production is obtained.

Optimizing Glass Foam Production from Recycled Sources: Influence of Variation in Cullet Color and Spent Alkaline Battery Components

Glass foams present a compelling opportunity for upcycling glass waste, offering a favorable combination of low weight, thermal insulation, and mechanical strength. Prior works demonstrated the feasibility of producing glass foams from glass waste and foaming agents sourced from synthetic textile waste, manganese oxides, and spent alkaline battery cathodes. This work explores the optimization of the process, investigating the impact of glass composition of differently colored glasses on final properties and incorporating entire alkaline batteries, encompassing both cathode and anode components. By carefully adjusting the composition, foaming agent content, and process temperature, customizable properties are achieved. Increasing foaming agent content or utilizing transparent glass improves insulation but lowers density and mechanical properties. Lowering foaming agent content or using brown/green glass enhances density and strength at the expense of insulation. Temperatures beyond 900 °C increase crystalline content, boosting mechanical performance without affecting density. This innovative approach not only offers a pathway to sustainable insulation materials but also underscores the potential for minimizing environmental impact through the efficient upcycling of glass waste.

A Cross-Scale Electrothermal Co-Simulation Approach for Power MOSFETs at Device-Package-Heatsink-Board Levels.

This paper proposes a cross-scale simulation approach for evaluating the steady-state electrothermal performance of power MOSFETs at the device-package-heatsink-board (DPHB) level. A co-simulation framework is designed by employing the iterative process of power loss and chip temperature to bridge the device and package-heatsink-board (PHB) level simulators. As a result, the cross-scale electrothermal coupling effect within multilevel settings is considered. Correspondingly, variation values in chip temperature and temperature-dependent drain current can be obtained at various voltage biases, level settings, and DPHB structural parameters, incorporating cross-level physical insights. The simulation results are compared with existing methods, and their features and limitations are discussed. Additionally, this paper also derives an empirical equation from the co-simulations to characterize the relationship between the drain current and the chip temperature under different operations exactly. A commercial MOSFET with TO-220F packaging is implemented in experiments to extract the chip temperature and drain current in electrothermal equilibrium. The method comparisons and fair agreement among simulations, equations, and measurements presents the proposed approach as generalized and powerful for describing variations in chip temperature and drain current considering from micrometer devices to millimeter packages-heatsinks-PCB boards, thus providing effective support for DPHB-level co-design.

Разработка устройства для обеззараживания ИК-излучением почвосмеси в тонком слое на конвейере

Pest and disease control in the cultivation of greenery is an integral part of obtaining a high-quality and high yield. Heat treatment is one of the best ways to combat plant diseases and pests and allows you to quickly create the necessary sterile conditions without the use of chemicals. A device for disinfection of soil mixtures in a thin layer by IR radiation on a conveyor is being developed for heat treatment. The prepared soil mixture from the feed hopper enters the conveyor belt in a thin layer. An IR emitter with adjustable power is installed above the conveyor belt. The movement of the conveyor belt should ensure heating in the soil mixture layer up to 100 ± 5 ° C. This is controlled by a temperature sensor, which sends a signal via a programmable relay to the conveyor motor and regulates its movement. The disinfection process allows to achieve high energy efficiency due to software regulation, taking into account optimal modes and control of the processing temperature. Keywords: DISINFECTION, IR RADIATION, HEATING, SURFACE, SOIL MIXTURE, DISEASES, PESTS, CONVEYOR

Aspects Regarding FSW and SFSW Welding of Copper Cu99

Copper is used in various industrial fields due to its characteristics and properties. The very high thermal conductivity of copper makes it difficult to weld it using conventional fusion welding processes. Friction stir welding FSW is a solid-state joining process of metallic materials, which can be used to perform copper welded joints. Using a liquid working environment in FSW welding (submerged friction stir welding SFSW) causes the decrease of the process temperature, which can be beneficial for copper. The paper presents aspects and results obtained by ISIM Timisoara regarding FSW and SFSW butt welding of copper Cu99 2.5 mm thick, using the same type of the welding tool. The obtained results will be useful for the start of the experimental researches of processing in air and in liquid environment FSP and SFSP of copper Cu99, which will be performed in the Nucleu PN 23 37 01 02 project underway at ISIM Timisoara.

Mathematical model for heat transfer during underground coal gasification process

Purpose. To develop a mathematical model of the “coal-gas” medium heat transfer during underground coal gasification to predict the combustion face advance velocity and the duration of gasification column mining. Methodology. To detect the temperature fields in the coal seam and gas, depending on the displacement length of the phase transition boundary, a boundary-value problem of mathematical physics has been developed. To solve this boundary-value problem, Boltzmann transformations, as well as methods for solving ordinary differential equations, are used. Newton-Raphson method, which has quadratic convergence, is used to find the roots of the transcendental equation. Findings. Tendencies in the formation of mathematical models when studying temperature fields around an underground gasifier have been analyzed, with highlighting their disadvantages. A mathematical model of heat transfer during underground gasification has been developed, taking into account the phase transition boundaries of the “coal-gas” medium. A computational experiment was conducted to determine the temperature of the phase transition boundary based on the length of the gasification column and the duration of the process. Originality. A mathematical model for heat transfer during coal gasification in the form of a boundary-value problem of mathematical physics, which consists of parabolic heat-transfer equations, the Stefan condition at the phase transition boundary, and the Dirichlet boundary conditions, has been constructed. As a result of solving the boundary-value problem, a self-similar solution has been obtained for the distribution of the coal seam and gas temperature fields, as well as the position of the phase transition boundary depending on the gasification duration and on the medium density, thermal conductivity coefficients, specific heat capacity of gas and coal, specific calorific value and temperature of coal combustion, initial coal temperature and constant temperature of the gasification process. The conducted analysis of numerical calculations provides a deeper understanding of the dynamics of underground coal gasification process and makes necessary corrections to achieve the maximum process efficiency. Practical value. A methodology for determining the displacement length of the phase transition boundary of the “coal-gas” medium has been developed, taking into account the change in the combustion face temperature along the gasification zone length depending on the duration of this process. Application of the methodology makes it possible to predict the time of mining the gasified coal column for drawing up a calendar plan for mining operations.

Biological traits of a commercial mussel species Mytilus platensis from the South Atlantic Ocean: Environmental drivers affecting on its intertidal population

Population density, morphometric relationships, maximum age and shell growth rate were studied in an intertidal commercial mytilid species, the blue mussel Mytilus platensis d’Orbigny, 1842, at Villa Gesell (37° 15′S; 56° 57′W), Argentina, Southwest Atlantic Ocean. The population density and mean shell length showed variation across the year, i.e., the month with the highest density (December) was mostly characterized by smaller sized individuals, representing the newly settled recruits during the austral summer months. Shell cross sections and acetate peels of M. platensis revealed an internal shell growth pattern alternating broad opaque and narrow translucent bands, corresponding to fast and slow-growing periods, respectively. Translucent bands representing external rings were formed mostly during July, coinciding with a decrease in sea water temperature (austral winter) and gonadal maturation processes. Data confirmed the annual formation of translucent bands in this species, showing a maximum age of 8 years. The generalized von Bertalanffy growth curve showed values of SL∞ = 38.46 mm, k = 0.28 yr−1 and t0 = −0.57 yr−1 (R2 = 0.80). Compared to studies of subtidal populations, lower shell growth rate in this intertidal population were observed, which may be associated with the stressful environmental conditions in this habitat, such as desiccation, exposure to waves and fluctuating sea water temperature. The characteristics described throughout the study highlight that the variability associated with intertidal environments could limit the sustainability of commercial exploitation of M. platensis in these ecosystems compared with conspecific subtidal populations.

Effect of hydrogen sulfide concentration on two-dimensional SnS2 film by atomic layer deposition in annealing process

Two-dimensional materials are widely studied due to its unique physical, optical, electrical properties, and good compatibility with various synthesis methods. And among the many fabrication methods, tin disulfide (SnS2) material, a two-dimensional (2D) material that can be achieved with accurate thickness control using atomic layer deposition (ALD), high uniformity and conformality even at low process temperatures is attracting attention. However, since the crystallinity of the thin film is low at a low process temperature, various post-annealing methods are being studied to compensate for film quality. In this work, we compared the crystal structures, chemical binding energies, and electrical properties of the thin films by post-annealing SnS2thin films according to the hydrogen sulfide concentrations of 4.00% and 99.99% in the hydrogen sulfide atmospheres. The crystallinity, grain size, and carrier concentrations of the SnS2thin film were the highest at a post-annealing temperature of 350 °C at a hydrogen sulfide concentration of 99.99%, and the chemical binding energies also corresponded with the standard Sn4+states, forming a pure 2D-hexagonal SnS2phase. In addition, SnS2thin films deposited via ALD showed high uniformity and conformality in large-scale wafers and trench structure wafers.

Selective Synthesis of 3D Aligned VO2 and V2O5 Carbon Nanotube Hybrid Materials by Chemical Vapor Deposition.

3D carbon nanotube hybrid materials containing VO2 and V2O5 evenly distributed onto vertically aligned carbon nanotubes (VACNTs) is reported. Adjustable loading of particles in controllable sizes and shapes onto the VACNTs was developed via a stepwise chemical vapour deposition (CVD) approach. Solid VO(acac)2 is chosen as vanadium source. CO2 acts as reactive gas for the pre-functionalisation of the VACNTs. The process temperature was identified as key parameter to control the deposited vanadium oxide phase. A temperature of 550 °C results in monoclinic VO2, while 600 °C results in the deposition of V2O5 onto the VACNT support. The morphology and the amount of deposited material was found to be dependent on the reactor dimensions and the degree of functionalisation of the carbon support. An increase of the D/G ratio of the VACNT from 0.75 to 1.08 caused by a CO2 treatment step within the process led to an increase of the particle coverage from a scarce coverage without prior CO2 treatment to a dense coverage of the VACNT support after 15 min of CO2 exposure time. Size and crystallinity of the as deposited particles can be further adjusted by a controlled heat treatment after VO(acac)2 precursor deposition.

Experimental study of vegetable oil droplets vaporization under low temperature conditions such as those found in diesel engine cold parts

This paper presents an analysis of three vegetable oil droplets vaporization process in the range temperature from 473 to 723 K corresponding to low temperature conditions found in diesel engine cold parts. This process is analyzed for a droplet evaporating in a hot environment at atmospheric pressure using the fiber-suspended droplet technique well used in the literature, and analyzing the droplet normalized square diameter and temperature evolution surrounding the droplet when vaporizing. The main difference between those already studied in literature is the range temperature which varies between 473 and 723 K in which vegetable oils vaporizing problems leading to deposits formation in the cold regions of diesel engines especially in direct injection. This presents a scientific challenge for resolving deposit formation. The findings reveal that vegetable oil droplets experience expansion and heating for temperatures below 623 K: no other changes are observed. Between temperatures of 623 and 683 K, an increase in temperature, expansion, and an inconsistent vaporization is observed. This is followed by a phase of low and constant vaporization. From 683 K, vegetable oils experience an initial stage of heating and expansion, which is accompanied by a phenomenon of puffing and bursting. Finally, in the last phase, residue formation occurs. Puffing and bursting phenomena manifest once the temperature reaches 683 K, indicating the emergence of substantial quantities of light compounds including carboxylic acids, aromatics, acrolein, ketene, and fatty acids. These compounds are formed through the thermal degradation and polymerization of vegetable oils. This process causes deposits to form in the colder areas of diesel engines.

Effect of High Processing Temperature on the Rheological and Morphological Properties of Recycled Polypropylene

Effect of High Processing Temperature on the Rheological and Morphological Properties of Recycled Polypropylene

Enhancing orthogonal finishing machining of Ti6Al4V with laser-ablated tool geometry modifications

Finishing machining of Ti6Al4V, known for its high strength and heat conduction resistance, demands optimisation to achieve high-quality end products. This study explores modifying the chip contact length on the rake face and altering the flank face with a cavity to minimise process forces and temperatures while maintaining cutting edge integrity. The research validates the manufacturability of ultra-short pulsed laser-ablated tool geometry modifications, indicating potential for industrial scale-up. Extensive experimental evaluations under dry conditions assess the impact of tool modifications at various feed rates for planing and turning. Significant reductions in process forces and temperatures were observed with rake face modifications, particularly at a cavity distance of approximately 34 µm. Ideal performance was noted for feed rates between 0.035 and 0.045 mm for planing and 0.040 to 0.045 mm/rev for turning. Smoothed Particle Hydrodynamics (SPH) simulations employing a Johnson-Cook material model were used to analyse chip formation and to predict the process forces. These simulations revealed a clear change in the chip formation and lower process forces and temperatures. The SPH results closely matched experimental outcomes, with a discrepancy of less than 7 % in cutting forces for both tool types, although feed forces were underestimated by about 50 %. The effect of the tool modification is reflected accurately at the respective feeds.

Design of Voltage–Current Reference Source in CMOS Technology

A design methodology for a resistorless low-power two-in-one voltage and current reference source working in subthreshold and moderate regions is described. The presented novel universal reference voltage–current source was implemented in ten different designs for seven different CMOS technologies. Six versions of these designs were silicon-proven using four different CMOS technologies. The example of implementation in 130 nm technology provides a reference current of 5 µA and reference voltage of 800 mV at supply voltages ranging from 0.9 V to 2.0 V with a total current consumption of 15 µA. The proposed circuit occupies a 1200 µm2 chip area and achieves 280 and 118 ppm/°C for all process corners and temperature variation from −40 °C to 125 °C. The power supply rejection ratio of output IREF without any filtering capacitor at 100 Hz and 10 MHz is 128 dB and 100 dB, respectively. The equivalent output current noise in the bandwidth from 1 Hz to 10 MHz reaches 9.1 nARMS.