Critical Nucleation Research Articles

Biological Condensate Growth: Examining the Impact of Solute Crowder on Size Expansion.

Biological condensation refers to the formation of micrometer-sized or smaller condensates by biological macromolecules, a process often influenced by the crowded cellular environment. Poly(ethylene glycol) (PEG) is commonly used to mimic cellular crowding, and its ability to reduce the critical nucleation concentration has been well established. However, its impact on condensate size has been less explored. This study investigates how PEG affects the size of condensates formed between protein TNP1 and DNA. Our experimental findings show that PEG molecules increase condensate size. Notably, at equal mass concentrations of PEG400, PEG3350, and PEG10000, longer PEG molecules have a much greater effect on condensate expansion. Computational simulations further reveal that longer PEG molecules enhance protein-DNA condensation more effectively and contribute to shaping the condensates into regular forms. Overall, our study provides key insights into how crowding factors influence the size and shape of colloidal growth.

Edge Electron Effect Induced High-Entropy SEI for Durable Anode-Free Sodium Batteries.

Anode-free sodium metal batteries represent great promising as high-energy-density and resource-rich electrochemical energy storage systems. However, the savage growth of sodium metal and continuous consumption hinder its stable capacity output. Herein, ordered flower-edges of zinc on Al substrate can induce high-entropy solid electrolyte interphase (SEI) to adjust sodium uniform deposition and extremely reduce electrolyte consumption with ultrahigh initial Coulombic efficiency (97.05%) for prolong batteries cycling life. Theoretical and experimental studies have demonstrated that the electron-donating property and exposed edge sites between (100) and (101) facets in zinc flower enhance anion adsorption onto the inner Helmholtz plane accelerating its interface decomposition. Additionally, the ordered zinc edges serve as homogeneous-nucleating template, leading to thin and inorganic-rich SEI layer (18 nm, ZnF2, NaZn13, NaF, and Na2CO3) with high-entropy discrete multicomponent distribution, so that fast and high-flux Na ions transport field, thereby reducing the critical nucleation barrier and promoting sodium high density nucleation (7.36 × 1013 N cm-2) and pyknotic growth (3 mAh cm-2, 22µm). The assembled anode-free sodium batteries exhibit high stability (86%, 90 cycles) under ultrahigh cathode loading (32 mg cm-2). Moreover, the anode-less single-layer pouch batteries exhibit a durable capacity retention of 99% after 600 cycles.

The Effect of Process Parameters on the Pore Structure of Lotus-Type Porous Copper Fabricated via Continuous Casting

The pores in lotus-type porous copper are formed due to the difference in hydrogen solubility between the liquid and solid phases of copper. In a pressurized hydrogen atmosphere, hydrogen gas is released at the gas release and crystallization temperature, which is the melting point of copper. This study systematically analyzes the effects of process parameters, including hydrogen ratio, total pressure, and continuous casting speed, on the pore structure of lotus-type porous copper, with the aim of identifying the most critical process parameters for controlling pore diameter and density. Within the hydrogen ratio up to 50%, it was observed that as the hydrogen ratio increases, the pores tend to increase in porosity, and the pore diameter increases. As the hydrogen ratio increased from 25% to 50%, the pore diameter increased from 300 μm to 400 μm, while the pore density decreased from 3.3 N·mm−2 to 2.8 N·mm−2. As the total pressure increased, the pore diameter tended to decrease, and the pore density increased. Specifically, when the total pressure increased from 0.2 MPa to 0.4 MPa, the pore diameter decreased from 1100 μm to 400 μm, while the pore density increased significantly from 0.5 N·mm−2 to 2.8 N·mm−2. In addition, as the continuous casting speed increased, 30 to 90 mm·min−1, the pore diameter decreased from 850 μm to 400 μm, and the pore density increased from 0.7 N·mm−2 to 2.8. N·mm−2. Specifically, the increase in total pressure led to a decrease in Gibbs free energy and a reduction in the critical pore nucleation radius, which promoted pore formation and resulted in the creation of more, smaller pores. These results suggest that total pressure is the primary factor influencing both pore diameter and density in lotus-type porous copper.

Vapor Nucleation on Hybrid-Wetting Nanoconvex Surfaces: The Competition between Intrinsic Wettability and Topography.

Hybrid-wetting surfaces with hydrophilic spots reduced from the micrometer to nanometer scale have been confirmed to enhance vapor nucleation while simultaneously minimizing droplet pinning. Given that surface topography also plays a critical role in influencing nucleation characteristics, the effect of competition between intrinsic wettability and topography on nucleation remains unclear when both surface topography and hydrophilic regions approach the critical nucleation size. This work investigated vapor nucleation on two types of hybrid-wetting nanoconvex surfaces. On random hybrid-wetting convex surfaces, the most negative potential energy sites were located at the sides of the convex structures, leading vapor to preferentially nucleate at these locations, consistent with observations on homogeneous surfaces. Despite similar average potential energy values across the surface, wettability variations in hydrophilic and hydrophobic atoms significantly alter the surface energy distribution. As the wettability difference between hydrophilic and hydrophobic atoms increases, stronger hydrophilic atoms generate relatively higher local energy regions, promoting vapor rapid nucleation. The edge effect still exists at a hydrophilic atom ratio of 10%, and competition among hydrophilic spots impedes vapor nucleation and growth. However, when the ratio increases to 40%, the increased surface average potential energy promotes the probability of vapor contacting the surface, leading to rapid vapor nucleation on the sides of the convex structures. In addition, surface potential energy analysis and the Monte Carlo method revealed that nucleation locations on nanoconvex surfaces are governed by the competition between intrinsic wettability and topography. When the magnitude of the potential energy generated by the hydrophilic atoms exceeds that from the topography, stronger solid-liquid interactions at the top of the convex structure increase the likelihood of vapor contacting the surface, resulting in nucleation at the top. Conversely, when the magnitude of the potential energy generated by hydrophilic atoms is lower than that from topography, nucleation preferentially still occurs on the sides.

A data-driven strategy for phase field nucleation modeling

We propose a data-driven strategy for parameter selection in phase field nucleation models using machine learning and apply it to oxide nucleation in Fe-Cr alloys. A grand potential-based phase field model, incorporating Langevin noise, is employed to simulate oxide nucleation and benchmarked against the Johnson-Mehl-Avrami-Kolmogorov model. Three independent parameters in the phase field simulations (Langevin noise strength, numerical grid discretization and critical nucleation radius) are identified as essential for accurately modeling the nucleation behavior. These parameters serve as input features for machine learning classification and regression models. The classification model categorizes nucleation behavior into three nucleation density regimes, preventing invalid nucleation attempts in simulations, while the regression model estimates the appropriate Langevin noise strength, significantly reducing the need for time-consuming trial-and-error simulations. This data-driven approach improves the efficiency of parameter selection in phase field models and provides a generalizable method for simulating nucleation-driven microstructural evolution processes in various materials.

Atomic scale in-situ observation of gas-solid interaction regulating the pre-nucleation process of Pd atomic clusters

Advancements in nanotechnology have propelled the understanding of atomic-scale nucleation processes, essential for the evolution of atomic manufacturing. The process of amorphous precursors nucleation showcases a complex transition influenced by various factors. Utilizing aberration-corrected ETEM and theoretical calculation, we explore the nucleation of amorphous Pd atomic clusters. This study examines the nucleation dynamics and gas-solid interaction regulating of Pd clusters on ultrathin carbon films, prepared via electron beam evaporation. HRTEM observation and FFT analysis reveal that, in the early stage of nucleation, Pd cluster growth predominantly follows an Ostwald ripening-like mechanism. Atoms from smaller clusters migrate and attach to larger ones, facilitating their progression to critical nucleation size. Environmental conditions significantly influence this process; hydrogen atmospheres lower the surface energy of Pd clusters, reducing the critical nucleation size, while argon atmospheres impede growth of Pd clusters by occupying migration sites on the carbon surface. These insights into atomic cluster behavior and environmental interactions are crucial for understanding the early stages of nucleation from amorphous to crystalline and can help opens new avenues for the controlled fabrication of materials with optimized functionalities.

Coupling effect of gas solubility in a solvent and substrate structure on performance in nanobubble morphological changes

The distribution morphologies of nanobubbles on Highly Oriented Pyrolytic Graphite (HOPG) surfaces prepared using the alcohol-water exchange test method were observed using atomic force microscopy. In situ observation revealed the distinct growth evolution behavior of nanobubble morphology. Molecular dynamics simulation was employed to replicate the experimental test and investigate the influence of the coupling effect of gas solubility and substrate structure on the morphological features of nanobubble distribution in alcohol-water exchange experiments. The results demonstrate that gas solubility plays a pivotal role in the nucleation of surface nanobubbles during alcohol-water exchange. Specifically, stable surface nanobubbles form only when the solubility exceeds 0.02535. Furthermore, under conditions where gas solubility satisfies the nucleation criteria, the surface potential energy of concave and defective structures exhibits concave characteristics, giving rise to the nucleation of cap-shaped nanobubbles. In contrast, the step structure, characterized by the smallest average surface potential energy, results in relatively flat properties in the lowest area, with nanobubble nucleation taking the form of layer-shaped features. yields relatively uniform characteristics at the lowest level, where nanobubble nucleation manifests in the form of layered features. As time progresses, cap-shaped nanobubbles coalesce, leading to the escape of gas molecules and subsequent dissipation, whereas the layer-shaped nanobubbles adsorb gas molecules from the solution, prompting their expansion.

Uncovering the combining V with Ni micro-addition alloying on the mechanical properties and multiphase transformation during solidification and homogenization of Al–Zn–Mg–Cu–Sc alloy

The ultimate tensile strength of the T6-aged Al–Zn–Mg–Cu–Sc alloy is improved by 24 MPa reached 667 MPa with the addition of 0.10 % V, 0.20 %Ni and decrease 0.1 %Sc. The thermodynamic and microalloying mechanisms of phase transformation during solidification and homogenization of Al–Zn–Mg–Cu–Sc–V–Ni alloy were clarified. The phase transformation model of Al3Sc (V, Ni) structure induced by V and Ni addition during homogenization was established. The calculation radius showed that coherent L12-ordered Al3Sc(V, Ni) nanoparticles were formed in the Al–Zn–Mg–Cu–Sc–V–Ni alloy, which had a small critical nucleation radius (22.0 nm). The large thermodynamic driving force and the high kinetic energy migration energy barrier of γ-Al7Cu4Ni and Al3Sc (V, Ni) phases led to the finer microstructure of grain. V element not only promoted the formation of Al21V2 phase containing Sc but also hindered the mutual diffusion of Al and (Sc, Ni) elements in the eutectic system via segregation at the α-Al/Al3Sc (V, Ni) interface, which improved the stability of the whole alloy. The edge nucleation of γ-Al7Cu4Ni phase upon its diffusion into a Sc-containing Al21V2 phase induced the formation of Al3Sc (V, Ni) structure, whereas the segregation of V and Ni further strengthened the alloy matrix.

Grain size dependence of twin nucleation in magnesium alloys

Twinning plays a prominent role in the plastic deformation of low-symmetry crystals such as magnesium alloys. However, the capture of twin nucleation has been challenging since the process is rapid and difficult to predict, making it impossible to observe directly. Because of this, the understanding of the fundamental twinning mechanism through experiments and simulation techniques incorporating twinning has progressed slowly. In this study, a quantitative analysis integrating an in-situ three-point bending experiment and crystal plasticity modeling was conducted on the twin nucleation in AZ31 magnesium alloys with different grain sizes. The threshold for triggering twin nucleation has been quantified. The prediction ability of three widely used criteria for twin nucleation, i.e., geometrically necessary dislocation (GND) density, von Mises stress, and stored energy density, is evaluated. The results suggest that only the stored energy density is able to capture the twin nucleation location accurately in all the considered grain sizes. The critical value exhibits an exponential reduction with the increase in grain size. Based on the quantitative analysis, the mechanism of the grain size effect on twin nucleation is proposed.

Interfacial Zn2+-solvation regulator towards reversible and stable Zn anode

Aqueous zinc-ion batteries (AZIBs) are fundamentally challenged by the instability of the electrode/electrolyte interface, predominantly due to irreversible zinc (Zn) deposition and hydrogen evolution. Particularly, the intricate mechanisms behind the electrochemical discrepancies induced by interfacial Zn2+-solvation and deposition behavior demand comprehensive investigation. Organic molecules endowed with special functional groups (such as hydroxyl, carboxyl, etc.) have the potential to significantly optimize the solvation structure of Zn2+ and regulate the interfacial electric double layer (EDL). By increasing nucleation overpotential and decreasing interfacial free energy, these functional groups facilitate a lower critical nucleation radius, thereby forming an asymptotic nucleation model to promote uniform Zn deposition. Herein, this study presents a pioneering approach by introducing trace amounts of n-butanol as solvation regulators to engineer the homogenized Zn (H-Zn) anode with a uniform and dense structure. The interfacial reaction and structure evolution are explored by in/ex-situ experimental techniques, indicating that the H-Zn anode exhibits dendrite-free growth, no by-products, and weak hydrogen evolution, in sharp contrast to the bare Zn. Consequently, the H-Zn anode achieves a remarkable Zn utilization rate of approximately 20% and simultaneously sustains a prolonged cycle life exceeding 500 h. Moreover, the H-Zn//NH4V4O10 (NVO) full battery showcases exceptional cycle stability, retaining 95.04% capacity retention after 400 cycles at a large current density of 5 A g−1. This study enlightens solvation-regulated additives to develop Zn anode with superior utilization efficiency and extended operational lifespan.

Study on the evolution of multistage and multiscale Ti-bearing precipitation and microstructure in ultrahigh-strength titanium microalloyed weathering steels

In this study, 900 MPa ultrahigh-strength weathering steels were successfully developed through thermomechanical controlled processing (TMCP). Advanced microstructure characterization, combined with precipitation thermodynamics and kinetics models, elucidated the evolution of Ti-bearing precipitation and microstructure. The results showed that coiling temperature (CT) significantly impacts phase fractions, grain boundary density, and misorientation angles, while both CT and finishing rolling temperature (FRT) influence grain sizes in acicular ferrite (AF) and granular bainite. The lower coiling temperature resulted in a higher dislocation density of the test steel, which provided more nucleation sites for AF and TiC, favoring a higher number of TiC particles and a higher proportion of AF. Above 1050 °C, the addition of nitrogen changed the shape of the precipitation kinetics curve, reduced the nucleation energy barrier of TiC, decreased the critical nucleation size, and improved the nucleation rate. Meanwhile, the addition of nitrogen accelerated the precipitation transformation of TiC, which promoted the formation of Ti(C, N). Furthermore, increasing the deformation stored energy (DSE) further accelerated the precipitation of Ti(C, N) and significantly increased the nucleation rate. The formation mechanism of large-size Ti(C, N) and the transformation mechanism of Ti(C, N) to TiC are revealed by precipitation thermodynamics and kinetics. The completion time of TiC precipitation on dislocations is shorter than that on grain boundaries, which results in the TiC on dislocations being prone to coarsening during prolonged coiling. These findings provide crucial insights for optimizing the industrial production of ultrahigh-strength titanium microalloyed weathering steels.

Theoretical investigation of Cu influence on the stability characteristics of T-phase in crossover alloys

Abstract In crossover Al-Mg-Zn alloys, the T-phase (Mg32(Al, Zn)49) is crucial for reinforcement. The critical nucleation size of the precipitated T-phase is notably reduced by Cu addition, as well as the activation energy. There is a lack of theoretical research on the influence of Cu elements on the stability of T-phases and mechanical properties. In this work, we systematically investigate the influence of varying Cu concentration on the T-phases by examining their stability, mechanical properties, and electronic structure characteristics through first-principles calculations. The findings reveal that the T-phase maintains lattice stability within the 0 to 5% Cu content range, with a linear decrease in the lattice parameter and formation energy (–0.16 ~ –0.15 eV/atom). Additionally, there is an observable positive correlation trend between the elastic moduli (B, E, and G) of the T-type phase and the Cu content. It is shown that the T-phase exhibits inherent ductility. Analysis based on Pugh’s criterion and Poisson’s ratio indicates a reduction in the ductility with increasing Cu content in the T-phase. This work theoretically validates the previous experimental observations and reveals the impacts of Cu concentration on the T-phase.

The rise and fall of adenine clusters in the gas phase: a glimpse into crystal growth and nucleation.

The emergence of a crystal nucleus from disordered states is a critical and challenging aspect of the crystallization process, primarily due to the extremely short length and timescales involved. Methods such as liquid-cell or low-dose focal-series transmission electron microscopy (TEM) are often employed to probe these events. In this study, we demonstrate that ion mobility spectrometry-mass spectrometry (IMS-MS) offers a complementary and insightful perspective on the nucleation process by examining the sizes and shapes of small clusters, specifically those ranging from n = 2 to 40. Our findings reveal the significant role of sulfate ions in the growth of adeninediium sulfate clusters, which are the precursors to the formation of single crystals. Specifically, sulfate ions stabilize adenine clusters at the 1:1 ratio. In contrast, guanine sulfate forms smaller clusters with varied ratios, which become stable as they approach the 1:2 ratio. The nucleation size is predicted to be between n = 8 and 14, correlating well with the unit cell dimensions of adenine crystals. This correlation suggests that IMS-MS can identify critical nucleation sizes and provide valuable structural information consistent with established crystallographic data. We also discuss the strengths and limitations of IMS-MS in this context. IMS-MS offers rapid and robust experimental protocols, making it a valuable tool for studying the effects of various additives on the assembly of small molecules. Additionally, it aids in elucidating nucleation processes and the growth of different crystal polymorphs.

Theoretical analysis of the initial nucleation characteristics of trace water vapor frosting on a cryogenic surface

In certain extreme conditions characterized by ultra-low water vapor content and ultra-low temperatures (e.g. cryogenic wind tunnel), trace water vapor frosting can also pose significant hazards. Considering the crucial role of initial nucleation on subsequent frosting processes, this study firstly investigated and compared the nucleation characteristics of frosting at different water vapor contents (0.1−1000 ppmv) from humid air to trace water vapor based on classical nucleation theory. The preferred nucleation phase diagrams and critical nucleation conditions were analyzed. Sensitivity of the nucleation mass transfer rate, as well as the frosting pathways were further identified. Results show that the nucleation characteristics of trace water vapor frosting (<100 ppmv) is significantly different from that of humid air frosting (>1000 ppmv). Trace water vapor frosting is more inclined towards desublimation nucleation due to its lower nucleation temperature and larger critical contact angle. The critical contact angles for 1000 ppmv, 100 ppmv and 0.1 ppmv are 49°, 75° and 120°, respectively. Furthermore, trace water vapor nucleation requires a greater subcooling degree, has a smaller critical nucleation radius, and is highly sensitive to surface contact angle and further-subcooling degree. At a surface contact angle of 120°, the nucleation subcooling degree of 0.1 ppmv is 2.9 K greater than that of 1000 ppmv. This study helps understanding the nucleation characteristics under different water vapor content conditions, which indicates that reducing subcooling degree and increasing contact angle are more effective anti-frosting methods than reducing water vapor content for trace water vapor frosting.

Bridging classical nucleation theory and molecular dynamics simulation for homogeneous ice nucleation.

Water freezing, initiated by ice nucleation, occurs widely in nature, ranging from cellular to global phenomena. Ice nucleation has been experimentally proven to require the formation of a critical ice nucleus, consistent with classical nucleation theory (CNT). However, the accuracy of CNT quantitative predictions of critical cluster sizes and nucleation rates has never been verified experimentally. In this study, we circumvent this difficulty by using molecular dynamics (MD) simulation. The physical properties of water/ice for CNT predictions, including density, chemical potential difference, and diffusion coefficient, are independently obtained using MD simulation, whereas the calculation of interfacial free energy is based on thermodynamic assumptions of CNT, including capillarity approximation among others. The CNT predictions are compared to the MD evaluations of brute-force simulations and forward flux sampling methods. We find that the CNT and MD predicted critical cluster sizes are consistent, and the CNT predicted nucleation rates are higher than the MD predicted values within three orders of magnitude. We also find that the ice crystallized from supercooled water is stacking-disordered ice with a stacking of cubic and hexagonal ices in four representative types of stacking. The prediction discrepancies in nucleation rate mainly arise from the stacking-disordered ice structure, the asphericity of ice cluster, the uncertainty of ice-water interfacial free energy, and the kinetic attachment rate. Our study establishes a relation between CNT and MD to predict homogeneous ice nucleation.

On-Surface Synthesis of 2D Polymers at the Liquid-Solid Interface

Unraveling the structure and dynamics of the formation of covalent and non-covalent organic-based 2D crystalline materials is key to controlling the quality of these materials, such as the defect density and their size. Understanding these characteristics is important for controlling their properties. This contribution highlights our efforts in using scanning probe microscopy, particularly scanning tunneling microscopy (STM), to visualize the structure and dynamics of substrate-supported metal-organic frameworks (sMOFs) and substrate-supported covalent organic frameworks (sCOFs) at the liquid-solid interface.We will focus on the growth of covalent organic frameworks, primarily based on boroxine chemistry, and reveal both qualitative and quantitative details of the nucleation-elongation processes in real-time and under ambient conditions. Sequential data analysis enables the observation of the amorphous-to-crystalline transition, the time-dependent evolution of nuclei, the existence of 'non-classical' crystallization pathways, and, importantly, the experimental determination of essential crystallization parameters with excellent accuracy, including critical nucleus size, nucleation rate, and growth rate. Other aspects that will be addressed include sCOFs and chirality, as well as the formation of multilayered sCOFs. Additionally, we demonstrate that in specific cases, the electric field between the STM tip and the substrate can induce, on demand, the polymerization or depolymerization process.

Harvesting nucleating structures in nanoparticle crystallization: The example of gold, silver, and iron.

The thermodynamics and kinetics of nanoparticle crystallization, as opposed to bulk phases, may be influenced by surface and size effects. We investigate the importance of such factors in the crystallization process of gold, silver, and iron nanodroplets using numerical simulations in the form of molecular dynamics combined with path sampling. This modeling strategy is targeted at obtaining representative ensembles of structures located at the transition state of the crystallization process. A structural analysis of the transition state ensembles reveals that both the average size and location of the critical nucleation cluster are influenced by surface and nanoscale size effects. Furthermore, we also show that transition state structures in smaller nanodroplets exhibit a more ordered liquid phase, and differentiating between a well-ordered critical cluster and its surrounding disordered liquid phase becomes less evident. All in all, these findings demonstrate that crystallization mechanisms in nanoparticles go beyond the assumptions of classical nucleation theory.

Modeling of Mode I crack-tip dislocation nucleation in three FCC materials: Ni, Cu and Al

An accurate estimation of the critical stress intensity factor for crack tip dislocation nucleation under Mode I loading is of great importance to determine whether a material is intrinsically ductile or not. Here, shear displacements and energy change at crack tip in FCC nickel, copper and aluminum are investigated during Mode I fracture process using atomistic simulations. In light of our simulation results, a new shear resistance model is formulated by a general Fourier expansion with coefficients identified by the computed energy curve. The new model involving the step formation energy which can be regarded as a new parameter and unstable stable stacking fault energy, reduces to Rice theory if no step exists. The criterion for nucleation is developed based on the idea that crack tip behaviors are controlled by the shear resistance and the maximum point serves as an obstacle to conquer. The predictions of the critical shear displacement corresponding to maximum shear resistance position and the critical nucleation energy show good agreement with simulation results. In addition, the new model can be further utilized to study the effect of complex stress state on Mode I crack tip dislocation nucleation.

Effect of cooling rate on solidification microstructure, microsegregation, and nanoprecipitates in medium carbon CrMo cast steel

Precipitation strengthening is a crucial method for enhancing the mechanical properties of steel. The bridgman directional solidification furnace, optical microscope (OM), scanning electron microscope (SEM), electron probe analyzer (EPMA) and transmission electron microscope (TEM) were used to investigate the effect of solidification cooling rate on the solidification microstructure, microsegregation, and nanoprecipitates in medium carbon CrMo cast steel. The results indicate that as the cooling rate increases, the solidification microstructure is significantly refined. The relationship between the cooling rate (CA) and primary dendrite arm spacing (PDAS, λ1) and secondary dendrite arm spacing (SDAS, λ2) are given by λ1 = 123.74 × C-0.4088A, λ2 = 66.63 × C-0.6532A. Solute elements like Cr, Mo, and V exhibit noticeable positive segregation in the inter-dendritic. When the cooling rate does not exceed 0.47 °C/s, the solute concentrations in the inter-dendritic increase with higher cooling rate, leading to a decrease in the effective solute partition coefficient. This phenomenon is primarily attributed to the back diffusion of solute elements during solidification. Following heat treatment, precipitation of M6C, V(C,N), and M23C6 occurs within the inter-dendritic regions. If the solidification cooling rate does not exceed 0.47 °C/s, the density and volume fraction of nanoprecipitates increase with higher cooling rate. This trend primarily results from the reduction in critical nucleation radius and critical nucleation energy, facilitating easier nucleation of nanoprecipitates.

Effect of multiple environmental conditions on the formation process and adhesion strength of ice on asphalt binder surface

Road icing caused by freezing rain significantly impacts driving safety. Since asphalt binder plays a pivotal role in pavement infrastructure, understanding the formation process and adhesion strength of ice on asphalt binder surfaces is crucial for assessing road icing risk. This work investigated the effect of different environmental conditions on asphalt-ice interface adhesion strength via a self-designed low-temperature adhesion testing system. In addition, the icing process on asphalt binder surfaces was observed to analyze the asphalt-ice adhesion strength formation mechanism. Results show that the completion time of water-ice phase transition signified the initial development of asphalt-ice adhesion strength. Moreover, as the internal structure of the ice evolved from transparent to needle-like fine lines to dense, the asphalt-ice adhesion strength gradually increased until it reached stability. At asphalt-ice adhesion began forming after 40 min and stabilized after 80 min, whereas at −8°C, adhesion strength started forming after 20 min and stabilized by 60 min. The growth rates of asphalt-ice adhesion strength for temperatures ranging from −2°C to −10°C were approximately 7.92 kPa/°C, 6.56 kPa/°C, 5.14 kPa/°C, 3.29 kPa/°C, and 1.49 kPa/°C, respectively, showing a positive correlation with temperature and a negative correlation with time. According to heterogeneous nucleation theory, the influence mechanism of temperature and water depth on the nucleation icing process and asphalt-ice adhesion strength is analyzed. lower temperatures lead to asphalt-ice adhesion strength increase originating from the larger supercooling, which reduces the critical nucleation energy and thus accelerates the ice nucleation rate. In addition, the increase in water depth promotes the formation of nucleation sites and further enhances the asphalt-ice adhesion strength. Finally, an asphalt-ice adhesion strength prediction model was developed, with PSO-SVM-G achieving over 90 % accuracy. These results provide insights for evaluating ice adhesion behavior on asphalt surfaces and designing anti-icing asphalt materials.