Rapid Cooling Research Articles

Effect of Rapid Cooling on Microstructure and Mechanical Properties in Friction Stir Welded Twin-Induced Plasticity Steel

Effect of Rapid Cooling on Microstructure and Mechanical Properties in Friction Stir Welded Twin-Induced Plasticity Steel

Case Study of Severe Accidental Hypothermia with Rapid Cooling, Preserved Shivering, and Consciousness with a Summary of Similar Case Reports.

We describe a case of severe accidental hypothermia of a kayaker with preserved consciousness and shivering despite a rectal temperature of 22.9°C following a 50-min immersion in 3°C water with an estimated core temperature cooling rate of 10.6°C/h. Based on survival at sea prediction curves and cooling rates from physiology studies, cold water (eg, 0-5°C) immersion is expected to drop core temperature by 2 to 4°C/h. Furthermore, accidental hypothermia classification systems predict that severely hypothermic patients are usually unconscious and not shivering. The patient in this report rewarmed rapidly at 3.6°C/h with only minimally invasive measures and was discharged fully neurologically intact. In 41 similar cases of survival in moderate to severe hypothermia with core temperatures <32°C due to cold water immersion, cold air exposure, or avalanche burial, mean cooling rates were 4.3±3.3°C/h (range 0.4-10.6°C/h). Including the current patient, shivering was reported in only four cases. We found several other cases of rewarming from moderate to severe hypothermia with only minimally invasive measures. The current and summarized cases lead us to conclude that patients may be at risk of severe hypothermia in <60 min of cold water immersion and that it is possible for severely hypothermic patients to have preserved consciousness, close to normal vital signs, and shivering. Minimally invasive or noninvasive rewarming of patients with severe hypothermia is also possible, especially in those who continue to shiver. Hypothermia management should not necessarily be guided by classification systems or core temperature alone but rather by a careful consideration of the entire clinical picture.

Impact of Rapid Cooling and Depressurization on Limestone Compressive Strength: Implications for CO2 Injection in Carbonate Reservoirs

Impact of Rapid Cooling and Depressurization on Limestone Compressive Strength: Implications for CO2 Injection in Carbonate Reservoirs

Experimental Investigation on the Damage Evolution of Thermally Treated Granodiorite Subjected to Rapid Cooling with Liquid Nitrogen

In many thermal geotechnical applications, liquid nitrogen (LN2) utilization leads to damage and cracks in the host rock. This phenomenon and associated microcracking are a hot topic that must be thoroughly researched. A series of physical and mechanical experiments were conducted on Egyptian granodiorite samples to investigate the effects of liquid nitrogen cooling on the preheated rock. Before quenching in LN2, the granodiorite was gradually heated to 600 °C for two hours. Microscopical evolution was linked to macroscopic properties like porosity, mass, volume, density, P-wave velocity, uniaxial compressive strength, and elastic modulus. According to the experiment results, the thermal damage, crack density, porosity, and density reduction ratio increased gradually to 300 °C before severely degrading beyond this temperature. The uniaxial compressive strength declined marginally to 200 °C, then increased to 300 °C before monotonically decreasing as the temperature rose. On the other hand, at 200 °C, the elastic modulus and P-wave velocity started to decline significantly. Thus, 200 and 300 °C were noted in this study as two mutation temperatures in the evolution of granodiorite mechanical and physical properties, after which all parameters deteriorated. Moreover, LN2 cooling causes more remarkable physical and mechanical modifications at the same target temperature than air cooling. Through a deeper comprehension of how rocks behave in high-temperature conditions, this research seeks to avoid and limit future geological risks while promoting sustainability and understanding the processes underlying rock failure.

Analyzing the Effects of Rapid and Natural Cooling Techniques on the Quality of Hand-Shaken Green Tea Beverages.

This study compared the quality of hand-shaken green tea prepared through rapid and natural cooling methods. Cooling is crucial in preserving green tea's flavor, aroma, and nutritional components. In the rapid cooling method, green tea is freshly brewed at an initial temperature of 95 °C for 25 min, and then rapidly cooled to 18 °C for 25 min. Conversely, the natural cooling method involves brewing tea at the same initial temperature and time, but allowing it to cool gradually to 30 °C over approximately 4-5 h at room temperature. This study's findings indicate that the rapid cooling method produced green tea with a more vibrant color and improved clarity versus the natural cooling method. Sensory analysis revealed that the taste and aroma of the hand-shaken green tea prepared using rapid cooling were perceived to be more refreshing and invigorating. However, the natural cooling method preserved a higher level of chemical components, including individual catechin caffeine, total polyphenol, soluble solids, reducing sugar, and total tannins. The essential amino acid content of the rapidly and naturally cooled green tea infusions was 6.85 and 13.55 μg/mL, respectively. The γ-Aminobutyric acid (GABA) content was 439.82 and 457.31 μg/mL, respectively. This study's findings suggest that rapid cooling during the preparation of hand-shaken green tea enhances its overall quality. The vibrant color, improved clarity, refreshing taste, and invigorating aroma make it a preferable choice for tea enthusiasts who seek an enhanced sensory experience and excellent quality.

Optimizing Advanced High‐Strength Steel Joints via Regional Rapid Cooling in Resistance Spot Welding

During resistance spot welding (RSW), the thermal cycles that occur cause microstructural differentiations in the heat‐affected zones of martensitic steels, leading to internal stresses. In this context, a new and innovative methodology has been developed to minimize the adverse effects of heterogeneous hardness changes in the welding area on joint durability. This methodology utilizes a unique prototype setup based on the regional rapid cooling (RRC) process, which is integrated into the welding machine and operates in synchronization with the machine during the process. Through this setup, the aim is to effectively control the microstructure and hardness values in the welding area. This innovative approach presents potential improvements in the field of welding technology by aiming to optimize material performance during the welding process. According to microstructure results, the RRC process has narrowed the heat‐affected zone to 1.27 mm, increased the hardness values by 9.2%, showed a 3% increase in tensile‐shear strength, a 9% increase in cross‐tension strength, and based on fatigue strength results, no fractures occurred in all specimens subjected to a force of 0.3 kN.

Influence of Residual Stress on Mechanical and Tribology Behaviors of Calcium-Phosphate Coating on Commercially Pure Titanium via Integrated Electrospinning and Rapid Heating and Cooling Process

Influence of Residual Stress on Mechanical and Tribology Behaviors of Calcium-Phosphate Coating on Commercially Pure Titanium via Integrated Electrospinning and Rapid Heating and Cooling Process

Effect of Local Rapid Cooling Heat Treatment on Residual Stress of Pressure Vessel Inner Wall Welding Layer

Effect of Local Rapid Cooling Heat Treatment on Residual Stress of Pressure Vessel Inner Wall Welding Layer

Development of new β Ti and Zr-based alloys in the Ta-(75-x)Ti-xZr system

The main objective of this study was to produce two new biomedical alloys, Ta-(75-x)Ti-xZr (x = 25, 50 wt%), and to carry out a detailed analysis of the crystal structures, phase composition, lattice parameters, hardness, and elastic modulus of the alloys under the influence of heat treatments. After melting (as-cast condition), the two alloys were subjected to two heat treatments carried out at a temperature of 1000 °C: one with slow cooling in the oven (SC) and the other rapidly cooled with ice water (RC). From the structural and microstructural characterizations (XRD, SEM, and Rietveld), it was observed that the Ta-(75-x)Ti-xZr produced are α+β type alloys. However, the Ta–25Ti–50Zr alloy contains a more significant amount of β phase due to the β stabilizing action of Zr combined with Ta as a typical β stabilizing element. Regarding the cooling after heat treatments, rapid cooling (RC) promoted the formation of the metastable α" phase, and heat treatment followed by slow cooling (SC) promoted the formation of the α+β phases. The alloys’ hardness, elastic modulus, and atomic packing factor (APF) were affected by changes in the α and α" phases fraction. The SC treatment increased APF, hardness, and elastic modulus, while the RC treatment decreased elastic modulus, optimizing it for biomedical applications.

Molecular Dynamics Research on Fe Precipitation Behavior of Cu95Fe5 Alloys during Rapid Cooling

To investigate structural changes, the Cu95Fe5 alloy system was subjected to cooling rates of 1 × 1013 K/s, 2 × 1012 K/s, 2 × 1011 K/s, and 2 × 1010 K/s using the molecular dynamics simulation method. The results revealed that decreasing the cooling rate caused an increase in the phase transition temperature. Further, the structure of the alloy system exhibited a tendency towards increased stability following cooling at lower cooling rates. The Fe precipitation behavior of the Cu95Fe5 alloys during cooling at the rate of 2 × 1010 K/s was further explored, with the results suggesting that the formation and growth of the Fe cluster is a continuous process governed by the nucleation and growth mechanism. The size and number of Fe clusters formed at different stages were found to be affected by three factors, namely, the interaction force between the Fe atoms, the diffusion ability of the Fe atoms, and the interfacial energy between the Fe cluster and Cu matrix. When the alloy temperature exceeded 1400 K, the accumulation of the Fe atoms was facilitated by their strong interaction. However, the high temperatures and the large diffusion coefficient of the Fe atoms acted as inhibitors to the growth of Fe clusters, despite the intense thermal activities. As the temperature was reduced from 1400 K to 1050 K, the Fe atoms moved with a reduced intensity in a narrower area, and both the number of Fe atoms in the largest cluster and the number of clusters increased due to the action of the interaction force between the Fe atoms. Upon lowering the temperature from 1050 K to 887 K, the size of the largest Fe cluster increased rapidly, while the number of clusters decreased gradually. The growth of the largest Fe cluster could be partly attributed to the diffusion of single Fe atoms into the cluster under the action of the interaction force between the Fe atoms, in addition to the gathering and combination of multiple clusters. When the temperature was lowered from 967 K to 887 K, the diffusion coefficient of the Fe atoms approached 0, indicating that the non-diffusive local structure rearrangements of atoms dominated in the system structure change process. The interface energy governed the combination of the Fe clusters in this stage. At a temperature below 887 K, the alloy crystallized, the activities of the Fe atoms were reduced due to a low temperature, and the movement range of the Fe atoms was small at a fast cooling rate. As such, both the size and number of Fe clusters showed no obvious changes.

Dental zirconia microwave-sintering followed by rapid cooling protocol

ObjectivesThis study aimed to evaluate the effect of microwave sintering temperature and cooling rate (MS) on 3Y-TZP ceramics and its influence on the ceramic microstructure and mechanical properties. Specifically, to optimize the sintering process, reducing the total sintering time compared to conventional sintering. Materials and methodsEighty-four pre-sintered Y-TZP discs (Vipi block Zirconn, VIPI) (ISO 6872) were divided into seven groups (n = 12) according to the sintering conditions: conventional sintering (CS) at 1530 °C for 120 min and microwave sintering at 1400 °C (MS1400) and 1450 °C (MS1450) for 15 min followed by different cooling conditions: rapid cooling (RC), cooling at 400 °C (C400) and 25 °C (C25). The specimens were submitted to apparent density measurements, X-ray diffraction analysis (XRD), scanning electron microscopy, and biaxial flexural strength test. Data was statistically analyzed through two-way ANOVA, Tukey, Sidak, Dunnett and Weibull (α = 0.05). ResultsAll MS1400 groups presented lower density values than the CS and MS1450 groups. Two-way ANOVA revealed that the MS temperature and cooling rate affected the biaxial flexural strength of the Y-TZP (p < 0.01). Group MS1400RC presented lower biaxial flexural strength values (681.9 MPa) than MS1450RC (824.7 MPa). The cooling rate did not statistically decrease the biaxial strength among the groups submitted to microwave sintering at 1450 °C. XRD analysis showed that the sintering and cooling temperature did not induce tetragonal to monoclinic phase transformation. ConclusionsMicrowave sintering at 1450 °C for 15 min followed by rapid cooling can be a viable fast alternative protocol for Y-TZP sintering, compared with the conventional sintering, reducing the total sintering time by 75% and reducing the energy used for the sintering process without affecting the Y-TZP biaxial flexural strength and relative density compared to the conventional sintering. Moreover, the microwave technique promoted smaller grains and did not induce monoclinic phase formation.

Effect of Fire Loading: Rapid Cooling on the Axial Response of Lightweight Geopolymer Concrete-Infilled Encased Circular Steel Columns

Effect of Fire Loading: Rapid Cooling on the Axial Response of Lightweight Geopolymer Concrete-Infilled Encased Circular Steel Columns

A New α + β Ti-15Nb Alloy with Low Elastic Modulus: Characterization and In Vitro Evaluation on Osteogenic Phenotype.

This study aimed to produce Ti-15Nb alloy with a low elastic modulus, verify its biocompatibility, and determine whether the alloy indirectly influences cellular viability and morphology, as well as the development of the osteogenic phenotype in cells cultured for 2, 3, and 7 days derived from rat calvarias. Two heat treatments were performed to modify the mechanical properties of the alloy where the Ti-15Nb alloy was heated to 1000 °C followed by slow (-5 °C/min) (SC) and rapid cooling (RC). The results of structural and microstructural characterization (XRD and optical images) showed that the Ti-15Nb alloy was of the α + β type, with slow cooling promoting the formation of the α phase and rapid cooling the formation of the β phase, altering the values for the hardness and elastic modulus. Generally, a more significant amount of the α phase in the Ti-15Nb alloy increased the elastic modulus value but decreased the microhardness value. After the RC treatment, the results demonstrated that the Ti-15Nb alloy did not present cytotoxic effects on the osteogenic cells. In addition, we did not find variations in the cell quantity in the microscopy results that could suggest cell adhesion or proliferation modification.

Lightweight and Flexible Phase Change Materials for Thermal Management with Integrated Rapid Heating and Cooling Functions

Lightweight and Flexible Phase Change Materials for Thermal Management with Integrated Rapid Heating and Cooling Functions

Study of Crystallization Kinetics of (Fe50Ni50)73.5Si13.5B9Nb3Cu1 Ribbons Prepared by Rapid Cooling Technique

Amorphous alloy ribbons of (Fe50Ni50)73.5Si13.5B9Nb3Cu1 were fabricated by rapid cooling technique on single copper wheel. After fabrication, the crystalline structure of the ribbons were examined by X-ray diffraction method. The results show that the samples possess a complete amorphous state. The crystallization process was studied by using a differential thermal analyzer (DSC). The DSC analysis show that there are two exothermic peaks corresponding to two crystalline phases appeared in the alloy ribbons. By changing the heating rate (i.e. 5, 10, 15, 20 and 25 oC/min) and by using the Kissinger method, The activation energy of crystallization of the crystalline phases determined for one phase was found to be E1 = 350 kJ/mol and for other one, E2 = 375 kJ/mol. Based on these results, we have chosen the appropriate annealing mode for the alloy ribbons. After annealing, the alloy ribbons were achieved nanocrystalline states of FeNi and α-Fe nano-particles with the grain size ranging from 5 to 15 nm and the fraction of crystallization between the crystalline and amorphous phases of 46, 67, 85 and 96 % respectively for the annealing regimes at 500 oC for 20, 30, 50 and 60 minutes.

Process Design for Manufacturing Fiber-Reinforced Plastic Helical Gears Using a Rapid Heating and Cooling System

In this study, a lightweight fiber-reinforced plastic (FRP) helical gear was fabricated to investigate the potential application of FRP in automobile parts that require high loads and reduced noise. High-performance aramid FRP processed using the wet-laid method was used in the tooth region, and SCR420 steel was used in the inner hub region. A hot-forming system that combines rapid induction heating and water channel cooling methods was developed to reduce the cycle time. The cooling water flow conditions were analyzed to precisely control the mold temperature. Additionally, a rotating extraction system was developed to mitigate the extraction difficulty owing to the helix angle to the extraction direction. Using the innovative hot-forming system developed in this study, a helical gear without any process-induced defects was fabricated with a significantly reduced cycle time. The performance of the gear was successfully estimated using gear durability, torsional strength, and motion noise tests. The use of FRP materials offers significant potential to realize lightweight components; however, certain challenges related to their properties that may limit their application must be addressed on a case-by-case basis.

Enhancement in Electrical Properties of Impact Polypropylene Copolymer for Cable Insulation Induced by Rapid Cooling

Impact polypropylene copolymer (IPC) is a promising eco-friendly power cable insulating material with great potential to replace the thermosetting cross-linked polyethylene (XLPE). This article compares the breakdown strength and water tree resistance of IPC and isotactic polypropylene (iPP) after different cooling rates. Unexpectedly, an abnormal enhancement of IPC’s insulating property is discovered. The breakdown strength and water tree resistance of IPC are both increased after rapid cooling, which is opposite to the electrical property deterioration generally found on iPP and XLPE with similar treatment. To reveal the mechanism of abnormal enhancement of IPC, the crystalline structure, phase morphology, and trap distribution are characterized. The results indicate that rapid cooling induces an abnormal increase in the crystallinity of IPC due to the formation of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> crystals, which in turn increases the deep trap level and density and leads to enhanced breakdown strength. Moreover, the formation of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> crystal can also enhance the inter-lamellar coupling and result in higher tensile yield strength, further, decreasing the water tree initiation probability. These results reveal that rapid cooling can significantly regulate the performance of IPC, which should be given serious consideration for the application of IPC in cable insulation.

Investigations on Temperatures of the Flat Insert Mold Cavity Using VCRHCS with CFD Simulation.

This paper adopted transient CFD (Computational Fluid Dynamics) simulation analysis with an experimental method for designing and surveying the quick and uniform rise in the temperature of the plastics into the insert mold cavity. Plastic injection molding utilizing VCRHCS (Vapor Chamber for Rapid Heating and Cooling System) favorably decreased the defects of crystalline plastic goods’ welding lines, enhancing the tensile intensity and lowering the weakness of welding lines of a plastic matter. The vapor chamber (VC) possessed a rapid uniform temperature identity, which was embedded between the heating unit and the mold cavity. The results show that the tensile strength of the plastic specimen increased above 8%, and the depths of the welding line (V-gap) decreased by 24 times (from 12 μm to 0.5 μm). The VCRHCS plastic injection molding procedure can constructively diminish the development time for novel related products, as described in this paper.

Variations in Stress Thresholds for Heated Granite Subjected to Rapid Cooling under Different Confining Pressures

Variations in Stress Thresholds for Heated Granite Subjected to Rapid Cooling under Different Confining Pressures

Research on Dynamic Compressive Performance and Failure Mechanism Analysis of Concrete after High Temperature and Rapid Cooling.

To investigate the dynamic compressive properties of concrete after high temperature and rapid cooling, an experimental study was carried out by considering five temperatures and four strain rates. The coupling effect of high temperature and strain rate on concrete damage morphology and mechanical parameters was comparatively analyzed. The main conclusions are as follows: the compressive damage morphology of concrete is affected by strain rate development trends of significant variability under different temperature conditions. As the strain rate increases, the compressive stress and elastic modulus of concrete are gradually increased. As the temperature increases, the increase in compressive stress is gradually reduced by the strain rate. For the temperatures of 20 °C and 800 °C, the increase in compressive stress by the strain rate is 38.69% and 7.78%, respectively. Meanwhile, SEM and CT scanning technology were applied to examine the mechanism of the effect of high temperature and strain rate on the mechanical properties of concrete from the microscopic perspective, and the corresponding constitutive model was proposed.