Solidification Properties Research Articles

A Review of Viscosity Measurement Techniques for Semi-Solid Metal Fluids in Thixoforming Processes

This paper critically reviews two viscometry techniques: capillary viscometers and parallel plate compression (PPC) viscometers, which are used in the viscosity measurement of semi-solid metal (SSM) fluids for thixo routes. Capillary and PPC viscometers have emerged as valuable viscometers in the study of thixo routes of SSM, with insights into their unique flow behavior being explored. Thixoprocessing of SSM is particularly suitable for specific alloys, especially those with specific solidification properties such as eutectics. It is a method of thixoforming that uses a material's non-dendritic microstructure. The thixo method's viscosity measurement is challenging, requiring sample preparation, sophisticated equipment, precise temperature, and pressure control. Previous studies have lacked sufficient information on measurement methods, viscometers, and limitations to measuring viscosity for the thixo route of SSM. Hence, this study thoroughly examines the principles, advantages, limitations, and application areas of viscometry methods. Several factors influencing viscosity measurements, such as temperature, shear rate, and sample preparation, are discussed in detail. A comparative analysis is conducted to evaluate the performance and accuracy of capillary viscometers and parallel plate compression viscometers. This review will provide a comprehensive understanding of SSM's viscometry techniques and assist researchers and practitioners in selecting the most appropriate method for their specific applications in semi-solid metal processing and characterization.

Solidification process of ABO3-type perovskites: Kinetic two-phase growth method with optimized potential

The functional properties of ABO3-type perovskite materials have garnered extensive attention, yet their solidification properties have remained challenging to investigate due to high-temperature environments and characterization limitations. In this study, molecular dynamics simulations are employed to comprehensively explore the melting, quenching, and crystal growth processes of SrTiO3 (STO) structural evolution. Through iterative fitting and optimization of ion effective charge, a set of potential functions capable of accurately simulating the high-temperature melting of STO are derived. The melting point obtained for STO (2403 K) using the two-phase coexistence method closely corresponds to the empirical value (2333 K), affirming the precision of the optimized potential. Quenching the molten STO yields an amorphous structure characterized primarily by Ti-O six-fold coordination, which increased by 13.09% when reduced to 300 K at a cooling rate of 0.1 K/ps. Notably, the results for different cooling rates revealed that slower cooling rates and lower temperatures yielded more ordered amorphous structures. To circumvent the formation of amorphous states during crystal growth of perovskite materials, we have developed a kinetic two-phase growth (KTPG) method. This approach regulates the cooling rate within a solid-liquid two-phase system, maintaining constant low supercooling at the interface to mimic STO crystal growth kinetics. Cooling at 0.01 K/ps to 1760 K leads to a notable transformation, with the percentage of Ti-O six-fold coordination reaching 90%. This signifies substantial progress in achieving crystal growth through this method, highlighting its efficacy in facilitating crystal formation from the melt phase.

The direct experimental observation and solidification mechanism of heavy metals in blast furnace slag glass‐ceramics

AbstractGlass‐ceramics with high performance and high crystallinity was produced using rare earth blast furnace slag (REBFS) as the primary raw material, along with composite nucleating agents Fe2O3 and Cr2O3. The migration pattern, distribution characteristics, and solidification properties of heavy metals in glass‐ceramics were investigated by the controlled heat treatment. The findings indicated that the heat treatment temperature has a significant effect on the distribution and color of heavy metals in glass‐ceramic. In the crystallized glass‐ceramic, spinel acts as the crystal core for heavy metal solidification, Cr, Cu, and Mn can exist stably in the spinel by the solid solution. The glass‐ceramic was expected to be used as a decorative building material.

Natural bentonite as an internal curing agent in the production of eco-friendly ultra-high performance concrete with low autogenous shrinkage

This study investigated the use of natural bentonite as a green internal curing agent to prepare eco-friendly ultra-high performance concrete (UHPC) with low autogenous shrinkage and excellent heavy metal ions solidification properties. A method based on the pore fractal dimension analysis was used for assessing the performance of UHPC. Results showed the use of bentonite as a replacement of cement could effectively reduce the autogenous shrinkage through its internal curing effect without compromising the compressive strength and workability of UHPC. The UHPC containing 4% bentonite showed the best volume stability and durability, with a 26.9% reduction in the autogenous shrinking compared to the control UHPC. The addition of bentonite further improved ion penetration resistance and solidification of heavy metal ion owing to its ion exchange capacity. However, the enhancement effect decreased when the bentonite content was too high due to the volume change of bentonite. Two kinds of pore classification dimensions, Dmin and Dmax, were obtained from NMR results to build good correlations with the autogenous shrinkage and durability, respectively. Finally, the ecological evaluation demonstrated that the designed UHPC with bentonite had relatively low environmental impact compared to other internal curing material, which was promising to generate a cleaner product in the near future.

Parameter optimization of unevenly spiderweb-shaped fin for enhanced solidification performance of shell and tube latent-heat thermal energy storage units

This paper investigates the solidification process of fin-strengthened shell and tube latent-heat thermal energy storage unit (LTESU). An unevenly spiderweb-shaped fin is proposed to fit better with shell and tube structures. This new type of fin is connected to the radial fins by annular fins. The uneven arrangement is achieved by varying the distance between the annular fins and the width ratio of the annular fin to the radial fin. Numerical simulation is used to investigate the strengthening effect of the novel fin on the solidification performance of LTESU. Moreover, to achieve better solidification properties, three parameters of the spiderweb-shaped fin are optimized for an equal share of metal fins (the position of the outermost annular fin γ, decreasing common difference of distance between annular fins ψ, and width ratio δ). The results show that there are optimum values for all three parameters to enable LTESU to achieve the shortest complete solidification time and the highest thermal energy release rate (TERR). The optimized spiderweb-shaped fin has a structure with larger annular fin spacing close to the inner tube, smaller annular fin spacing away from the inner tube, and thicker radial fins, thinner ring fins. It is recommended that the configuration parameters for the spiderweb-shaped fin are γ = 0.94, ψ = 0.05, and δ = 0.10. Compared to conventional rectangular fins, it ultimately reduces the complete solidification time by 88.9 % and increases the TERR by 7.8 times.

Depth optimization of solidification properties of a latent heat energy storage unit under constant rotation mechanism

Depth optimization of solidification properties of a latent heat energy storage unit under constant rotation mechanism

Injectable Lyophilized Chitosan-Thrombin-Platelet-Rich Plasma (CS-FIIa-PRP) Implant to Promote Tissue Regeneration: In Vitro and Ex Vivo Solidification Properties.

Freeze-dried chitosan formulations solubilized in platelet-rich plasma (PRP) are currently evaluated as injectable implants with the potential for augmenting the standard of care for tissue repair in different orthopedic conditions. The present study aimed to shorten the solidification time of such implants, leading to an easier application and a facilitated solidification in a wet environment, which were direct demands from orthopedic surgeons. The addition of thrombin to the formulation before lyophilization was explored. The challenge was to find a formulation that coagulated fast enough to be applied in a wet environment but not too fast, which would make handling/injection difficult. Four thrombin concentrations were analyzed (0.0, 0.25, 0.5, and 1.0 NIH/mL) in vitro (using thromboelastography, rheology, indentation, syringe injectability, and thrombin activity tests) as well as ex vivo (by assessing the implant's adherence to tendon tissue in a wet environment). The biomaterial containing 0.5 NIH/mL of thrombin significantly increased the coagulation speed while being easy to handle up to 6 min after solubilization. Furthermore, the adherence of the biomaterial to tendon tissues was impacted by the biomaterial-tendon contact duration and increased faster when thrombin was present. These results suggest that our biomaterial has great potential for use in regenerative medicine applications.

Analysis of melting and solidification performance of bionic snowflake fin horizontal Triplex-tube latent heat storage system based on response surface method

For the low thermal conductivity of phase change materials and other characteristics, a crossed snowflake fin Triplex-tube thermal energy storage (TTES) is proposed, and the analysis of melting and solidification of phase change material (PCM) by applying the numerical simulation method in the comprehensive thermal performance study. The three-casing phase change heat storage unit filled with RT55 is the object of this paper, and firstly, the cross distribution of snowflake fins into 8 fins is studied, and in the analysis of the thermal performance of TTES, the integrated heat storage (release) time, heat storage (release) and heat storage (release) temperature are used as evaluation indicators. By investigating the melting and solidification properties of PCM, the bifurcation angle of the best thermal performance is 60°, and the best fin profile is obtained by reasonable simplification for the purpose of maximum heat storage. The response surface method (RSM) is then used to optimize the size structure of the fins for the purpose of maximum melting heat storage and maximum solidification heat release of TTES, and the heat function equations of the melting and solidification processes of PCM are fitted, and the optimal regions of the melting and solidification processes of TTES are obtained. Finally, the optimization results show that when the length of the fin is 11 mm and the width of the fin is 0.8 mm, TTES has the best overall thermal performance. Compared with before optimization, the heat of PCM melting accumulation increased by 3.92 kJ and the heat of PCM solidification exotherm increased by 5.773 kJ.

Coupling effects of SiC and TiB2 particles on crack inhibition in Al-Zn-Mg-Cu alloy produced by laser powder bed fusion

A novel Al-Zn-Mg-Cu alloy free of cracks was produced utilizing laser powder bed fusion (LPBF) and modified with SiC and TiB2 particles. The interdependent effects of SiC and TiB2 particles on morphology, microstructure, and crystallographic texture were examined. The mechanisms behind phase evolution and crack inhibition were elucidated. The results show that a nearly dense Al-Zn-Mg-Cu alloy could be obtained when the mass fraction of SiC and TiB2 particles was 4%. TiB2 particles remained stable and acted as nucleation agents in the molten pool. Partial SiC particles reacted with the Al matrix to form rod-like Al4C3, lamellate Al4SiC4, and flocculent Si phases, which provided nucleation agents and liquid replenishment for matrix grains. The columnar grains of the matrix were refined into equiaxed grains, and the average size decreased from 37.15 μm to 7.54 μm. The preferential growth of grains along the (001) 〈001〉 direction was suppressed and transformed into a disordered random growth. The innovative Al-Zn-Mg-Cu alloy demonstrated an ultimate tensile strength of 492±12 MPa and an elongation of 7.2%±0.7%. The microhardness was enhanced, and the microhardness heterogeneity was reduced. The solidification properties were regulated, the temperature interval between solidus and liquidus was narrowed, and the liquidity of the molten pool was improved. The hot cracking of Al-Zn-Mg-Cu alloy was inhibited due to the interdependent effects of grain refinement by TiB2 particles and sufficient liquid metal replenishment by SiC particles.

Characterization of precipitation, evolution, and growth of MnS inclusions in medium/high manganese steel during solidification process

MnS as a main manganese-containing inclusion in medium/high manganese steel, which can be determined to the mechanical properties of steel. However, the precipitation and evolution mechanism of MnS in medium/high manganese steel is still unclear due to the special solidification properties and element segregation behavior. Hence, the effects of sulfur content, manganese content and cooling rate on the precipitation, evolution, and growth behavior of MnS inclusions in medium/high manganese are various experimentally characterized and thermodynamically elucidated in the present work. The results of 2D and 3D observation indicated that the morphology of MnS in medium manganese steel were transformed from globular and spindle-like (type I MnS) into large-sized rods (type II MnS) and dendritic (type D MnS), when sulfur content was increased from 78 ppm to 1578 ppm. Particularly, the spatial distribution and structure of MnS inclusions are elaborated in detail through X-ray micro-CT observations, which are discussed by defining the quantitative topography parameters and statistical analysis. Based on in situ CSLM observations, MnS precipitation path in high sulfur medium manganese steel was monitored as L → (L + δ + MnS) → (δ + MnS) → (δ + γ + MnS) → (γ + MnS) → (α + γ + MnS) → (α+MnS). Simultaneously, the Scheil-solidification calculations demonstrated that MnS is precipitated at the interdendritic region where the solid-liquid states are coexisted, which is caused by the segregation of sulfur and manganese. Moreover, increasing sulfur content generates the earlier precipitation, and leads to the significant increase in the number and size of MnS inclusions. Besides, the increase of manganese content promotes the transition of MnS from globular to polyhedral shape, which is attributed to the dissociative eutectic reaction of MnS formation preferentially takes place earlier in case of high manganese steel. It is also found that the decreasing of cooling rate and increasing the manganese content tends to increase the number and size of MnS inclusions, which is resulted from the long growth times of high manganese steel induced by large solid-liquid temperature differences. This work provides a systematic understanding of the precipitation and evolution of MnS inclusions in medium/high manganese steel.

Influence of Recycled Fine Aggregate Content on Properties of Soft Soil Solidified by Industrial Waste Residue.

The influence of recycled fine aggregate content on the properties of soft soil solidified by industrial waste residue was systematically studied. First, the addition of recycled fine aggregate may provide skeleton support, which was conducive to improving the solidification properties. Comparing the addition of recycled fine aggregate content and a composite solidification agent separately, the compressive strength increased 48.01 times and 1.32 times, respectively. Second, the composition and quantity of the hydration products were analyzed by X-ray diffraction (XRD) and thermal gravity analysis (TG/DTG). In addition to silicon dioxide and aluminum oxide, a number of new minerals, including hydrated calcium silicate, calcium hydroxide and ettringite, were produced under different recycled fine aggregate contents. The diffraction peak of hydrated calcium hydroxide was weak, which indicated that the crystallinity and relative content was low. The main reason for this was that it was consumed as the activator of the secondary hydration reaction of blast furnace slag. With the increase in recycled fine aggregate content, the total weight loss (hydration products, crystal water, impurities) increased significantly, at rates of 6.9%, 7.0%, 7.2%, 8.8% and 9.7%. The addition of recycled fine aggregate does not change the composition and quantity of the hydration products, and the increased weight loss in this part might be caused by the cement paste attached to the surface of the recycled fine aggregate. Finally, their microstructure was analyzed by scanning electron microscopy (SEM). Larger and more pores appeared in the solidification system with the increase in recycled fine aggregate, and a large amount of ettringite was prepared. An excess in recycled fine aggregate caused more pores, and the negative impact of too many pores exceeded the lifting effect of the aggregate, resulting in the decline of its mechanical properties. Therefore, there was a suitable range for the use of recycled fine aggregate, which was not more than 40%. In conclusion, recycled fine aggregate not only acts as a skeleton to improve solidification strength, but could also realize the comprehensive utilization of waste, which provided a new scheme for solid waste utilization and soft soil solidification.

Analysis of scale and frame interface effects on the solidification properties of solar salt in mesopores

The intermittency and instability of solar irradiation can be effectively overcome by using medium- and high-temperature composite phase change materials (PCMs) for latent heat storage. Studies using metals and organics as phase change materials show that the phase change behavior of mesoporous composite phase change materials is affected by the constraint effect, and its thermophysical parameters (such as phase change point and phase change latent heat) are significantly different from those of macro volume. However, at present, research on molten salt phase change materials, which are widely used in the field of medium- and high-temperature research, is insufficient. Molecular dynamics simulations combined with experimental methods were used to analyze the changes in the freezing point, supercooling degree and enthalpy of solidification of solar salt in mesoporous composite phase change materials, which were based on the self-diffusion coefficient and the potential energy-temperature curve. The results show that a larger mesoporous size leads to a higher freezing point of the solar salt. At the same scale, with the increase in Al2O3 content in the framework, the freezing point of the solar salt first decreases and then increases. The supercooling degree of solar salt decreases with increasing scale. When the mass content of Al2O3 in the framework is in the range of 25 wt%-40 wt%, the supercooling degree of solar salt increases gradually; in contrast, it decreases in the range of 40 wt%-50 wt%, and finally, it increases again in the range of 50 wt%-75 wt%. The latent heat of phase transition increases with increasing scale. With the increase in Al2O3 content in the framework, the latent heat of phase transformation first decreases, then increases, and finally stabilizes. Al2O3 and SiO2 in the interface of the frame can promote heterogeneous nucleation and provide a substrate for the nucleation of molten solar salt. They also reduce the degree of supercooling. It is found that the effect of Al2O3 on nucleation is more significant.

Development of the molten pool and solidification characterization in single bead multilayer direct energy deposition

Although single-layer directed energy deposition has been extensively studied, an in-depth understanding of the cladding melting and solidification mechanism of single bead multilayer directed energy deposition is equally promising for industry, considering practical application scenarios. Based on the single-layer directed energy deposition, a numerical model of multilayer directed energy deposition was developed and validated to reveal the cladding forming process and solidification structure of multilayer directed energy deposition. The simulation results show the complex Marangoni convection pattern generated by the surface tension gradient in the melt pool. Moreover, the multilayer directed energy deposition enhances the penetration effect of the melt pool under the influence of the heat accumulation effect, resulting in a cross-layer mass transfer different from that of the single-layer directed energy deposition. The evolution of the multilayer cladding from columnar crystals at the bottom to equiaxed crystals at the top and the shift of its growth orientation were also analyzed based on the obtained solid-liquid interface temperature gradients and solidification velocities during the solidification of the melt pool. Finally, the relationship between cladding grain size and solidification properties was theoretically predicted by counting the grain size of different layers in the cladding, and the effect of grain growth on the mechanical properties was superficially discussed. • Penetration of multilayer deposition melt pools enhanced by heat accumulation effects. • Cross-layer mass transfer exists for multilayer deposition. • "C" or "U" type of grain growth orientation transition. • The recrystallization after solidification promotes the mechanical properties.

Preparation of ethyl cellulose particles with different morphologies through microfluidics.

The sizes and shapes of polymer particles determine their performance and application. In this paper, ethyl cellulose particles with different morphologies are generated through extraction and solidification in a microfluidic device with double T-junctions. Droplets of ethyl acetate containing ethyl cellulose are formed first, then, pure water is employed to extract the solvents in the droplets and the ethyl cellulose is solidified to form monodisperse particles. By changing the flow rates of the continuous phase and the dispersed phase and the concentration of ethyl cellulose, red-blood-cell-like, doughnut-like, dimpled and spherical particles are fabricated, and the regime of different particle morphologies is given. The more important is that the physical mechanisms and explanations of the formation of different particle morphologies are clearly disclosed by analyzing the circulation flows outside and inside the droplets. The flow patterns in the microchannel, and the diffusion and solidification properties of the molecules are the key factors that affect the final morphology of particles. Due to the circulation, there are two stagnation points at the front and rear of the droplet, and they are the approximate locations where the dimple in the dimpled particle, the hole in the doughnut-like particle and the two pits in the red-blood-cell-like particles are formed. These analysis and results are useful in flow chemistry, in the fabrication of particle materials, and so on.

Analysis of microstructure, kinetics of isothermal solidification and mechanical properties of IN718/MBF-20/SS316L TLP joints

ABSTRACT In this research, transient liquid phase (TLP) bonding of IN718 and SS316L dissimilar alloys was carried out using MBF-20 amorphous interlayer. The effects of bonding temperature and time ranging from 1030°C to 1110°C and 1–30 min on the microstructure and mechanical properties of the bonded samples were studied. The mechanism of the microstructure formation and the solidification sequence at the joint area were discussed. Two diffusion models assuming stationary and moving solid/liquid interface were used to study the isothermal solidification kinetics and the time required for the complete isothermal solidification (tf) at different temperatures was predicted. The results suggest that the tf values obtained by the moving interface approach are closer to those of the experiments. The minimum difference between the experimental value of tf and that calculated by the moving interface approach was about 26%, while it was about 106% by considering the stationary interface approach. A more uniform hardness distribution across the joint area and the highest shear strength values were observed in the samples with complete isothermal solidification. The maximum shear strength of 440 MPa was obtained for the sample bonded at 1030°C for 30 min. This was attributed to the formation of a eutectic-free joint in these samples.

Solidification, Microstructure, and Mechanical Properties of Mg-Nd-Gd-Zn-Zr Magnesium Alloy with 1.5 Samarium

The influence of samarium (Sm) content on the solidification characteristics, microstructure, and mechanical properties of Mg–2.8wt%Nd–1.5wt%Gd–0.5wt%Zn–0.5wt%Zr magnesium alloy was studied. The cooling curves and microstructure analysis results showed that Sm rare earth element refined the grains of the alloys, where the solidification time of α-Mg phase of decreased as addition of Sm, which reflected to the microstructure of alloy and the grains became refined, also Sm combined with the initial phase of the intermetallic base alloy and crystallized along the grain boundaries. In addition, Mg41Sm5, Mg3Zn6Sm and (Mg, Zn)3Sm new intermetallic phases were formed as addition of Sm. Both grain refinement and formed intermetallic phases led to the improvement in hardness and tensile strength.

A Review of SLMed Magnesium Alloys: Processing, Properties, Alloying Elements and Postprocessing

Selective laser melting (SLM) is an additive manufacturing method with rapid solidification properties, which is conducive to the preparation of alloys with fine microstructures and uniform chemical compositions. Magnesium alloys are lightweight materials that are widely used in the aerospace, biomedical and other fields due to their low density, high specific strength, and good biocompatibility. However, the poor laser formability of magnesium alloy restricts its application. This paper discusses the current research status both related to the theoretical understanding and technology applications. There are problems such as limited processable materials, immature process conditions and metallurgical defects on SLM processing magnesium alloys. Some efforts have been made to solve the above problems, such as adding alloy elements and applying postprocessing. However, the breakthroughs in these two areas are rarely reviewed. Due to the paucity of publications on postprocessing and alloy design of SLMed magnesium alloy powders, we review the current state of research and progress. Moreover, traditional preparation techniques of magnesium alloys are evaluated and related to the SLM process with a view to gaining useful insights, especially with respect to the postprocessing and alloy design of magnesium alloys. The paper also reviews the influence of process parameters on formability, densification and mechanical behavior of magnesium. In addition, the progress of microstructure and metallurgical defects encountered in the SLM processed parts is described. Finally, this article summarizes the research results, and with respect to materials and metallurgy, the new challenges and prospects in the SLM processing of magnesium alloy powders are proposed with respect to alloy design, base material purification, inclusion control and theoretical calculation, and the role of intermetallic compounds.

Preliminary 3D printing of large inclined-shaped alumina ceramic parts by direct ink writing

Three dimensional (3D) printing technology by direct ink writing (DIW) is an innovative complex shaping technology, possessing advantages of flexibility in fabrication, high efficiency, low cost, and environmental-friendliness. Herein, 3D printing of complex alumina ceramic parts via DIW using thermally induced solidification with carrageenan swelling was investigated. The rheological properties of the slurry under different thermally-induced modes were systematically studied. The solidification properties of thermally-induced pastes with varying contents of carrageenan were optimized. The experimental results showed that the optimized paste consisting of 0.4 wt% carrageenan could be rapidly solidified at about 55 °C, which could print inclined-plane more than 60° in vertical without support, resulting in better homogeneity of the green body. A nearly pore-free structure was obtained after sintering at 1600 °C for 2 h.

Bifunctional Additives To Improve the Cold Flow Properties and Oxidation Stability of Soybean Oil Biodiesel

Biodiesel is a well-established biofuel that contains unsaturated and saturated fatty esters, and their contents influence oxidation stability and solidification properties, respectively. Also, the...

Study on solidification properties of chemically bonded phosphate ceramics for cesium radionuclides

Chemically bonded phosphate ceramics (CBPC) are prepared by the acid-base neutralization reaction of MgO and KH2PO4, which has a wide application prospect in the field of solidifying high-level liquid wastes and heavy metals. Herein, the effect of Cs+ on the solidifying process of the CBPC matrix with different M/Ps is studied through the change in pH values of the hydration process, the microstructure, and the phase composition of hydration products, as well as the compressive strength and leaching rate of the solidified form. The results show that with the increase in the Cs+ content, although the initial compressive strength of the solidified form with the M/P ratio in the range of 6:1 to 10:1 decreases, the compressive strength of the specimens reached 7 MPa after curing for 6 h, which was suitable for the rapid emergency treatment of Cs-containing wastes. Cs+ participates in the hydration reaction of the CBPC matrix but does not change the type of hydration products. With the addition of Cs+, the microstructure of hydration products changes from dense prismatic crystals to loose and porous cluster-like materials. The existing forms of Cs+ in the CBPC matrix are MgCsxK1-xPO4·6H2O and Cs3PO4. Generally, CBPC solidified form has an excellent solidification performance on Cs+; the normalized leaching rate of Cs+ in CBPC solidified form is in the range of 1.3127·10−6 ~ 9.1362·10−6 g/(m2·d), and the effective solidification rate is more than 99.136%.