Proper Heat Research Articles

Li2TiSiO5 Glass Ceramic as Anode Materials for High-Performance Lithium-Ion Batteries

We report a cost-effective way to synthesize the lithium silicate nano-glass ceramics for high-performance Li-ion batteries (LIBs). By proper heat treatment on the precursor glass, we succeeded in ...

Analysis of the non-isothermal resin impregnation process of carbon fibre reinforced composite wing spar structure

This paper presents non-isothermal resin impregnation process of high-performance light weight composite wing spar structure for trainer aircrafts. The manufacturing process of the spar is simulated in PAM-RTM software. In this research developed a reliable model of resin impregnation process simulation to determine the exact infusion time and optimize the resin inlet ports for large scale aircraft structure without using the expensive trial and error experimental approches. The work reported the use of different heating temperature processes to manufacture wing spar from carbon fibre-reinforced epoxy resin matrix composite laminates by using VARI. The influence of heating temperature during the infusion stage on the resin viscosity and impregnation time was analyzed. These results indicate that a proper heating temperature during the infusion process is necessary for quality control and manufacturing time reduction. The error between theoretical simulation and experimental studies is no more than 10%.

Combined cooling, heating, and power generation performance of pumped thermal electricity storage system based on Brayton cycle

Pumped thermal electricity storage (PTES) is considered as a promising mechanical energy storage technology owing to the advantages of high energy density, high efficiency, and no geographical restrictions. PTES system has great potential as a primary mover of the combined cooling, heating, and power (CCHP) system since energy is stored in the form of heat and cold energy which can be effectively delivered and converted to electricity. In this study, a novel CCHP system based on Brayton-based PTES system is proposed. An unsteady model was established to simulate the system and explore its potential of energy storage and delivery. The characteristics of system operating under different modes have been explored to obtain a complete map of system coefficient of performance (COP) under the cyclic stable states. Performance of the system is evaluated for energy requirements of an office building located in Norway. The obtained results showed that the COPs of the electrical storage, combined heating and power, and CCHP modes achieved 63.5%, 137.9%, and 188.1%, respectively, and the exergetic efficiency increased by 1.4% compared with the situation of electricity storage. Proper active heat and cold delivery from hot and cold reservoirs can improve the electrical efficiency and discharge stability. This system is therefore very worthy of being practical applied and popularized.

Microstructure and Mechanical Properties of Friction Stir Welded Austenitic-Ferritic Stainless Steels Using Staggered Joint Configuration

Dissimilar friction stir welding of 304 austenitic stainless steel and 430 ferritic stainless steel was performed by using staggered butt joint configuration. Under proper heat input, welding experiments were carried out to study the effect of tooth dimension on material flow, microstructure evolution and mechanical properties of the joint. The results indicate that the material flow tends to improve with reduced the tooth width. However, when the tooth width is reduced to 1 mm, the mixing degree of base metals in stir zone becomes worse due to the lack of softened metal. It is noted that joint 2 with a tooth width of 2 mm is characterized by river pattern and shows various flow directions in different regions of the stir zone. This pattern is formed by the mixed structure of austenite and ferrite with various grain sizes. Joint 2 presents the maximum tensile strength in all specimens and failed in the ferritic base metal.

Monitoring and analysis of the effects of atmospheric temperature and heat extreme of the environment on human health in Central Iran, located in southwest Asia

Investigation of temperature extremes is very important as one of the most important climate parameters in different parts. If exposed to enough heat, humans will suffer from extreme heat. Maximum temperature and heat can adversely affect many living organisms. The effects of extreme heat on people with chronic lung disease, including asthma and emphysema, are greater; even for people with healthy lungs, outdoor activities are not recommended during high ozone levels. The purpose of this study is to monitor and analyze the effects of atmospheric temperature extreme and extreme heat on human health in Central Iran. Therefore, the minimum and maximum data of 15 synoptic stations in the study area for the period (1988–2018) using hybrid artificial neural network (HANN) and adaptive neuro-fuzzy inference system (ANFIS) models were used. Finally, multi-criteria decision-making (MCDM) models TOSIS and SAW were used to prioritize the areas exposed to rising temperature. The results showed that according to ANFIS modelling for predicting extreme temperatures, the lowest mean training error and the mean error of validation for the minimum temperature were equal to 0.10 for the Yazd Station and 1.66% for the Damghan station. The lowest mean training error and the mean error of validation for the maximum extreme temperature obtained 0.016 for the Garmsar station and 9.39% for the Shahroud station. The maximum extreme temperature of two stations of Garmsar and Bafgh (1 and 0.9689, respectively) was more exposed to extreme temperatures based on the TOPSIS model. Garmsar and Salafchegan Stations (1 and 0.9873, respectively) were more exposed to extreme temperatures based on the SAW model. Climate change is fundamentally changing the Earth’s climate system in a way that directly and indirectly endangers human physical and mental health. Severe increase in temperature is directly associated with death from cardiovascular and respiratory diseases, especially in the elderly. Also in the study area, the house is a place for peace and comfort for every human being. Climatic and weather conditions have a direct impact on creating a sense of comfort in any architectural space. Proper heating and air conditioning in the interior of the building is another case of architecture that will not be easy because this architectural issue is related to the comfort or non-comfort of man, and the concepts of heat or cold are mostly due to the natural feeling of man and his physiological conditions. The rising trend of thermal stresses in the studied stations increases the need to pay attention to the issue of thermal stresses and the spread of diseases (heat attack, syncope, and muscle cramps) in terms of crisis planning and management.

Effect of heating rate during solution treatment on microstructure, mechanical property and corrosion resistance of high-strength AA 7075 alloy

The heating rate during solution treatment exerted great influence on the final grain structure of AA 7075 alloy processed by thermo-mechanical treatment (TMT). In case of rapid heating rate, particle-stimulated nucleation (PSN) of recrystallization occurred and fine equi-axed structure with an average grain size of ~9 μm was obtained. On the contrary, when a slow heating rate was adopted, the resulting recrystallized grains were rather coarse and elongated (average grain length > 100 μm). After peak-ageing treatment, the mechanical property and corrosion resistance of 7075 sheets were closely associated with those grain structures. Specifically, two kinds of sheets exhibited equivalent strength while the ductility of fine-grained sample is considerably increased to 18.5%, 49% higher than that (12.4%) of coarse-grained sheet. Meanwhile, inter-granular corrosion (IGC) and exfoliation corrosion (EXCO) tests certify that the fine-grained sheet exhibited significantly enhanced corrosion resistance. Effective grain refinement induced by rapid solution treatment accounts for the notable increment in both ductility and corrosion resistance. Our results demonstrate that the comprehensive properties of 7000 alloys might be tailored by adopting proper heating rate when the alloys are subjected to solution treatment.

Influence of Particle Reinforcement and Heat Treatment on the Wear Resistance of Inductively Melted Hardpaint Coatings

Wear-resistant coatings can reduce the high economic damage caused by wear processes. In this study, various protective layers based on the alloy X400CrVMo17-15-2 were investigated. Commonly, the prealloyed metal powder is used for plasma transferred arc powder surfacing. However, in this work, the cost-efficient hardpaint technology was used to produce particle-reinforced (fused tungsten carbides) and non-reinforced coatings. To analyze the wear behavior, the coatings were subjected to abrasion wear and scratch tests. For the abrasion wear test, a grinding pin (Al2O3) is pressed with a defined force against the surface of the rotating sample for 6 h. For the scratch test, a loaded diamond pyramid indenter was employed to create a circular groove on the coatings at a predefined speed. The wear grooves were analyzed with the aid of laser scanning microscopy. In comparison to the coatings in the as-processed condition, the non-reinforced protective layers were investigated after quenching, with and without deep cryogenic treatment, and tempering. The determination of proper heat treatment parameters was supported by computational thermodynamics. It has been confirmed that it is possible to improve the wear resistance of the unreinforced coatings by heat treatment. However, the reinforced layers showed the highest resistance against abrasion.

Improving mechanical properties of selective laser melted Co29Cr9W3Cu alloy by eliminating mesh-like random high-angle grain boundary

Selective laser melting (SLM) has been attracting increasing attention as a suitable route for fabricating personalized orthopedic implants to address patient–prosthesis mismatches and has been used for producing Co29Cr9W3Cu alloys in our previous study. However, SLM technology can result in the formation of mesh-like random high-angle grain boundaries (indicated as molten pool boundaries) and accumulation of residual stress in the microstructure, possibly causing an unstable mechanical property. In this study, the research on the relationship between microstructural evolution and mechanical properties was performed on the SLM-produced Co29Cr9W3Cu alloys with different heat treatments to improve the reliable mechanical property of the SLM-produced Co29Cr9W3Cu orthopedic implants. It was found that the microstrucutre with mesh-like random high-angle grain boundaries could be eliminated during recrystallization, replaced by the one with equiaxial structure containing the Σ3 grain boundaries (annealing twin). Most importantly, the combined effect of eliminating the mesh-like random high-angle grain boundaries and residual stress and generating the Σ3 grain boundary contributed to an increase in elongation from 12.49% of the as-SLM-produced one to 23.38%. Proper heat treatment is considered to be an efficient strategy to improve the mechanical properties of the SLM-produced Co29Cr9W3Cu alloy with a desired tensile ductility.

The Experimental Study of the Utilization of Recycling Aggregate from the Demolition of Elements of a Reinforced Concrete Hall

The article shows a case study as to whether the thermal and mechanical recycling of concrete is suitable for concrete debris from the demolition of structural elements of a 30-year-old industrial hall. The experiment included 10 series of new composites made from heated recycled concrete aggregate (HRCA) subjected to different variants of heat treatment and one additional control series with only natural aggregate (NA). The compressive strength of the new concretes has been determined. The microscopic observations of HRCA have also been made. The test results revealed that proper heat treatment of concrete rubble makes it possible to obtain a high-quality recycled coarse aggregate, which can be used as a 100% replacement for natural coarse aggregates in new concretes.

Nanostructured Carbide-Free Bainite Formation in Low Carbon Steel

It is an important challenge to reduce the carbon content in nanostructured bainitic steels for commercialization purposes while still being able to gain the desired microstructural characteristics in nanoscale and not to deteriorate the strength–ductility combinations. That is the point at which an appropriate heat treatment procedure design would be an important parameter. This article aims to investigate how to obtain nanostructured bainite in steel with 0.26 wt% carbon content by applying multi-step austempering procedures. One-, two- and three-step austempering processes have been implemented, and proper heat treatment temperatures and approaches were selected based on dilatometry tests. Results indicated that it has become possible to achieve bainitic ferrites and austenite films with overall thicknesses of 164, 145 and 132 nm and 134, 105 and 90 nm at the end of one-, two- and three-step austempering heat treatments, respectively. Meanwhile, microstructural characteristics resulted in enhanced mechanical properties with ultimate tensile strength (UTS) of 1435, 1455 and 1428 MPa in combination with elongation levels of 15.4, 13.6 and 11.4% after implementing those heat treatments. Finally, it has been shown that applying the multi-step austempering heat treatments resulted in enhanced yield strength and impact toughness values due to the microstructural characteristics and proper heat treatment procedure design.

CANNING FOOD IN SEMI-RIGID POLYMERIC AND COMPOSITE CONTAINERS

For thermal preservation of food, various types of retail polymeric packaging can be used: rigid, semi-rigid, flexible, and other kinds of containers. To make polymeric (plastic) containers usable for thermal sterilisation, and to ensure long storage of food, they should have a barrier layer that will make them heat-resistant, prevent oxygen ingress, and preserve the product’s quality and nutritive value. Every polymer material has its individual heat resistance characteristics. This paper considers such retail containers for food packaging as a composite can made of metal with a plastic lid and a semi-rigid heat-resistant polymer container with a foil cover. When using different container types for heat sterilisation and prevention of physical defects in cans, the following technological characteristics of cans should be taken into account: closure strength, depressurisation pressure, method of closure, diameter of a container’s opening, absence or presence of a stiffness relief on the cover, temperature of packaging, and other factors. The research includes analysis of existing types of retail composite and polymeric containers for canning food using different heat sterilisation methods. The theoretical and experimental research conducted has resulted in obtaining the values of the closure strength of the containers, an important parameter without which proper heat sterilisation of a product would be impossible. Developing scientifically proved parameters and modes of high-temperature sterilisation of meat and fish products in semi-rigid heat-resistant composite metal-plastic containers will allow enterprises to manufacture high-quality and safe canned food with high nutritive value.

Design of a pilot-scale microwave heated chemical vapor infiltration plant: An innovative approach

A hybrid Microwave-assisted Chemical Vapor Infiltration (MW-CVI) pilot plant to produce silicon carbide-based Ceramic Matrix Composites was designed, built and setup, as a part of the European project HELM. Being different from the existing lab-scale MW-CVI equipment, this pilot plant was designed with the idea of a further industrial scale-up.In order to enable the infiltration of the large samples of interest in industrial applications, the reactor was designed with the internal microwave cavity acting as an overmoded resonator at the frequencies of interest. The designed pilot plant allowed proper microwave heating of cylindrical samples of diameter doubled with respect to typical lab-scale preforms, with reproducible operating conditions in terms of transmitted/reflected power. First infiltration trials resulted in an average reaction efficiency of 25 % with the desired inside-out silicon carbide infiltration. The main steps of the design and the results of the first infiltration tests are discussed in this paper.

Mechanical and Microstructural Characteristics of Conventional and Robotic Gas Metal Arc Welded Low Carbon Steel Joints: A Comparative Study

In the recent automobile era, SAE 1022, low carbon manganese steel is widely used in structural members of automobiles. These steels possess good weldability and need proper heating treatment conditions when high thickness sections are being used in the structural application. Mostly, gas metal arc welding (GMAW) is preferred in automobile industries to have which produces better penetration with some minor defects like improper fusion of sidewall, etc. The increasing demand in the field of the automobile led to the attention over automated GMAW is being preferred to reach better productivity with zero defects. The samples were welded by the conventional GMAW method and automated through a robot. From the experimental test results, welding current of 450A, welding speed of 350 mm/min and a land height of 4 mm yielded a maximum tensile strength of 647 MPa and hardness of 275 HV in the coarse-grained heat-affected zone region with a robotic mode of GMAW. The comparative study proved that automated process produced better mechanical properties and improved efficiency.

Self-heating effects and hot carrier degradation in In0.53Ga0.47As gate-all-around MOSFETs

In0.53Ga0.47As based gate-all-around (GAA) metal-oxide-semiconductor field-effect transistors (MOSFETs) are being pursued as a promising solution to high speed ultra-large-scale integration chip design because of improved gate-channel electrostatic, excellent immunity to short channel effects, high carrier mobility and increased drain current. However, the GAA devices are highly prone to self-heating, and hot carrier injection (HCI) induced effects because of the absence of a proper heat take out mechanism. In this paper, 3-D electrothermal simulations are performed on In0.53Ga0.47As GAA MOSFETs using the hydrodynamic model to access the impact of self-heating on the electrical characteristics of the device. The Fiegna hot-carrier injection model is used in simulations to estimate the HCI into the oxide region. A thorough understanding of dependencies of lattice temperature and carrier temperature on spacer length, drain voltage, gate voltage, and thermal contact resistance is acquired. HCI degradation dependence on thermal contact resistance is also extensively studied using the Sentauras based TCAD simulator.

Semi-Solid Precision Forming Process of High-Strength and Wear-Resistant Aluminum Matrix Composites

A layered composite structural model with an outer wear-resistant layer of high-silicon aluminum alloy and an inner layer of ultra-high strength aluminum alloy is designed. A scaling brake drum part with layered composite was prepared by semi-solid precision forming process. The effects of process parameters such as casting temperature, specific pressure, solid layer temperature and heattreatment system on the composite interface were investigated. The results show that the casting temperature and solid layer temperature had a great influence on the interface recombination. The high forming specific pressure could effectively restrain the growth of secondary dendritesof the composite, and the proper heat treatment process could improve the morphology of the composite interface. A scaling brake drum component with A390/7050 layered composite structure was well prepared under optimal conditions.

Investigation of the effect of low temperature aging on the mechanical properties and susceptibility to sulfide stress corrosion cracking of 22%Cr duplex stainless steel

Duplex stainless steels (DSS) are corrosion resistant alloys largely used in the oil and gas production industry. Optimum properties are usually obtained with equal fractions of ferrite (δ) and austenite (γ) in the microstructure, which can be obtained by a proper solution heat treatment. However, work hardening can be used for applications where mechanical resistance must be increased, such as in casing and tubulars for oil and gas production. These pipes operate under high pressure in a harsh environment, composed by oil and high chloride water, low pH and high H2S and CO2 partial pressures. Additional strengthening can also be provided by low temperature aging which promotes the fine precipitation of a Cr-rich α’ phase by spinodal decomposition of ferrite. In this work, a DSS with 22%Cr (UNS S31803) received with an un-balanced microstructure (64% of ferrite), was aged at 475 °C for 8 h. For comparison, the material was correctly solution treated to obtain a balanced microstructure, and aged in the same way of the as received one. The effects on tensile mechanical properties, hardness and impact toughness were determined. The sulfide stress corrosion (SSC) susceptibility was evaluated by slow strain rate tensile (SSRT) tests in low pH and high pH2S chloride solution.

Optimization of Heat Treatment Parameters of 25Cr–8Ni–4Mo–N Cast 5A Duplex Stainless Steel Using Thermodynamic Modelling and Taguchi Methodology

Duplex stainless steel (DSS) is having an equal fraction of ferrite and austenite. Chromium, Nickel, Molybdenum, and few minor alloying elements constitute a DSS system, which makes metallurgy of the system complex. Proper heat treatment is need of the hour when it comes to expecting desired properties from the material, subjected to a specific working environment. DSS is one of the favourite choices for oil and gas industries. This study focuses on optimizing the heat treatment parameters and heat treating the as-cast 5A DSS and investigating microstructural evolution of the material subjected to various quenchants such as brine, water, and polyethylene glycol. Heat treatment temperatures, quenching media, and the quenching time have been selected in accordance with ASTM standards. Thermocalc TCFE8 database is being used for understanding the material response to various heat treating temperatures.

Thermal state of transiently accreting neutron stars with additional heating beyond deep crustal heating

Abstract As some neutron star transients require an additional unknown heat source (referred to as “shallow heating”) to explain their high temperatures at the beginning of quiescence, we investigate the effect of shallow heating as well as compressional heating on the thermal state of transiently accreting neutron stars with the use of evolutionary calculations in the present work. Through comparing our theoretical predictions of the equilibrium redshifted luminosities $(L_{\gamma}^{\infty})$ produced by both deep crustal heating and shallow heating/compressional heating for different time-averaged mass-accretion rates $\langle\dot{M}\rangle$ with 35 updated observations of soft X-ray transients, the results show that both shallow heating and compressional heating make significant contributions to the equilibrium redshifted luminosity. The hotter sources (XTE J1701, MAXI J0556, EXO 0748, Aql X-1 etc.) with higher accretion rates are more likely to be explained with the effect of shallow heating or compressional heating. In addition, for a proper shallow heat $q_\mathrm{sh}$ and mass-accretion rate $\dot{M}$, the effect of shallow heating could be simulated by compressional heating.

New High-Hardness Low-Alloy Wear-Resistant Ledeburitic Steel and the Prospects of Its Application at Negative Temperatures

The structure, the mechanical properties, and the impact toughness in the temperature range from +20 to –70°C of a new low-alloy wear-resistant ledeburitic 220Kh2FYu steel are studied. After proper heat treatment, the steel is shown to have the structure of a natural precipitation-hardened composite material and a high hardness (68–70 HRC). The developed steel is compared with 12Kh2N4VA steel.

Optimization of liquid hot water pretreatment on Hybrid Pennisetum anaerobic digestion and its effect on energy efficiency

To overcome the inherent complexity of lignocellulosic biomass and improve its biological conversion efficiency, the central composite surface response methodology was used to optimize the process variables (temperature, reaction time and liquid-to-solid ratio) in liquid hot water pretreatment for biomethane production from the anaerobic digestion of Hybrid Pennisetum (a typical energy crop in southern China). Temperature, reaction time and water content were varied between 160–200 °C, 20–60 min and 60–90 mL respectively. The biomethane yields from pretreated material were considered as response variables to different processes conditions. Results showed untreated Hybrid Pennisetum had a biomethane potential of 218.6 L/kg volatile solid (VS) (corresponding to a biodegradability of 62.6%). The effect of liquid hot water pretreatment on the biomethane yield was distinct. Pretreatment severities less than 4.55 resulted in increased biomethane yields. However, further increasing the severity led to lower biomethane yields. The optimum biomethane yield (290.6 L/kg VS) was obtained from pretreated Hybrid Pennisetum at 175 °C for 35 min, with the highest biodegradability of 83.2%. Energy balance showed that, under the optimal pretreatment condition, the highest energy conversion efficiency of 76.1% was attained in theory. If the process energy inputs are included, a process energy efficiency of 51.7% could be realized with proper heat recovery.