Heterogeneous Nucleation Method Research Articles

Confined Mo2C/MoC heterojunction nanocrystals-graphene superstructure anode for enhanced conversion kinetics in sodium-ion batteries

Heterostructure design and integration with conductive materials play a crucial role in enhancing the conversion kinetics of electrode materials for metal-ion batteries. However, integrating nanocrystal heterojunctions into a conductive layer to form a superstructure is a significant challenge, mainly due to the difficulty in maintaining the structural integrity. Here we report a unique glucose-induced heterogeneous nucleation method that enables the independent manipulation of nucleation and growth of Mo2C/MoC heterojunction nanocrystals within 2D layers. Our investigations reveal that the rGO-Mo2C/MoC-rGO superstructure is formed by a topological transformation induced by subsequent heat treatment of the initial hydrothermally prepared rGO-MoO2-rGO precursor. This novel structure embeds Mo2C/MoC heterojunction nanocrystals within a 2D graphene matrix, providing enhanced mechanical stability, accelerated Na+ transport, and improved electron conduction. Ex situ XRD and Raman spectroscopy analyses reveal that the rGO-Mo2C/MoC-rGO superstructure significantly enhances the stability and reversibility of anodes. Leveraging these unique characteristics, the newly developed superstructural anode exhibits remarkable long-term cycling stability and outstanding rate performance. As a result, superstructure anodes demonstrate superior electrochemical capabilities, delivering a specific capacity of 106mAh/g after enduring 5000 cycles at 1 A/g. Our study underscores the critical importance of superstructure design in propelling the advancement of battery materials.

Hollow-structured covalent organic framework decorated with FA-PEG: A biocompatible nanocarrier for targeted and pH-responsive release of doxorubicin

Hollow-structured covalent organic framework decorated with FA-PEG: A biocompatible nanocarrier for targeted and pH-responsive release of doxorubicin

Preparation of modified fly ash-based, core–shell inhibitor and its effect on suppression of Al-Mg alloy dust explosion

Dust explosions caused by energetic metals pose a significant risk to process industries, making it crucial to develop high-performance explosion inhibitors. In this study, the modified power plant solid waste fly ash (FA) was confirmed as a raw material for the preparation of core-shell inhibitors to efficiently suppress dust explosion of Al-Mg alloy. The interfacial compatibility of FA was dramatically improved by using alkali hydrothermal modification and organic modification. It formed a well-coated nano-Mg(OH)2 cladding layer on the surface of modified FA by the heterogeneous nucleation method. In a vertical combustion pipe and a 20 L spherical explosion device, the suppression effect of this novel core-shell inhibitor ([email protected](OH)2) was investigated. The experimental results showed that the addition of 60 wt% of [email protected](OH)2 reduced the maximum flame velocity (Vmax), velocity to the top of the pipe (Vtop), and average pulsation degree (Vap) by 87.9 %, 92.5 %, and 87.7 %, respectively, and the peak flame temperature (Tp) declined to 298 °C. The maximum explosion pressure (Pmax) and the maximum explosion pressure rise rate ((dp/dt)max) were reduced by 86.1 % and 92.9 %, respectively. Combining the analysis results of SEM, EDS, XRD, and TG-DSC, the suppression mechanism of [email protected](OH)2 was explained in depth, mainly from the heat absorption, coating effect, gas dilution, and radical adsorption. This work not only sheds new light on the design of dust explosion suppression functional materials but also broadens the application of industrial solid waste FA.

Mechanical property and cutting performance of self-lubricating cermet tools with the addition of core-shell powders

Mechanical property and cutting performance of self-lubricating cermet tools with the addition of core-shell powders

Sintering behavior and microstructure of (1-x)MgAl2O4-xMg2TiO4 spinel solid solutions prepared by isostructural heterogeneous nucleation

Magnesium aluminate (MgAl2O4) spinel has grasped considerable attention in high-temperature application by right of its excellent properties. However, the poor sintering behavior of MgAl2O4 is detrimental to its further development. In the present work, the application of isostructural heterogeneous nucleation method provides a novel idea for optimizing the sintering behavior of refractory materials. A series of (1-x)MgAl2O4-xMg2TiO4 (x = 0, 0.02, 0.04, 0.06, 0.08, and 0.1) spinel solid solutions with a present ration of components were fabricated from light calcined magnesia, reactive alumina and pre-preparation Mg2TiO4. The effect of Mg2TiO4 heterogeneous nucleating agent on the crystalline phase, densification, and microstructure evolution of MgAl2O4–Mg2TiO4 spinel solid solutions was studied. The XRD, XPS, and EDS results showed that Mg2TiO4 entered the lattice of MgAl2O4 to form a spinel solid solution, and the heterovalent substitution process was identified, where Ti4+ and Mg2+ ions of larger radius in the Mg2TiO4 replaced the Al3+ of smaller radius in the MgAl2O4. For the sample at x = 0.08, the spinel solid solutions exhibited the optimized densification with a relative density of 93.3%, an apparent porosity of 1.2%, and a compressive strength of 84.5 MPa. A significant increase in densification was related to the lattice distortion induced by ion size mismatch during the heterovalent substitution, thus accelerating the diffusion rate of Mg2+ and Al3+ ions in the spinelisation state. Moreover, the solid solubility content of Ti4+ in the MgAl2O4–Mg2TiO4 spinel solid solutions had a significant effect on the grain morphologies. The Mg2TiO4 heterogeneous nucleating agent significantly increased the spinelisation rate of MgAl2O4 spinel with negligible effect on densification.

Preparation of CePO4 Nanowires Coated on ZrO2 Substrates by A Heterogeneous Nucleation Method

Preparation of CePO4 Nanowires Coated on ZrO2 Substrates by A Heterogeneous Nucleation Method

Significantly improved interfacial properties and wave-transparent performance of PBO fibers/cyanate esters laminated composites via introducing a polydopamine/ZIF-8 hybrid membrane

Polydopamine hybrid zeolitic imidazolate framework-8 (PDA*ZIF-8) membrane, synthesized by zinc nitrate hexahydrate (ZnNO 3 •6H 2 O), 2-methylimidazole (2-MI), and dopamine (DA), uniformly grows on the surface of poly( p -phenylene-2, 6-benzobisoxazole) (PBO) fibers by heterogeneous nucleation method to obtain PBO@PDA*ZIF-8 fibers. PBO@PDA*ZIF-8 fibers are then applied as the reinforcement, bisphenol A dicyanate ester (BADCy) as the matrix, and PBO@PDA*ZIF-8 fibers/BADCy wave-transparent laminated composites are prepared by high-temperature molding. Results indicate that PDA*ZIF-8 membrane increases the surface roughness and chemical activity of PBO fibers. The interlaminar shear strength (ILSS) and flexural strength of PBO@PDA*ZIF-8 fibers/BADCy laminated composites are 45.3 and 656.3 MPa, respectively, which are increased by 23.4% and 11.7% compared with those of PBO fibers/BADCy composites (587.4 and 36.7 MPa). The dielectric constant and dielectric loss values at 1 MHz are 2.76 and 0.0046, respectively, lower than PBO fibers/BADCy (3.06 and 0.006). At 0.3–40 GHz, PBO@PDA*ZIF-8 fibers/BADCy laminated composites have excellent wave-transparent performance (The simulated wave-transparent rate is greater than 87%, d = 1.5–3.5 mm). Meanwhile, the corresponding volume resistivity and breakdown strength are 3.7 × 10 15 Ω•cm and 23.61 kV/mm, higher than PBO fibers/BADCy composites (2.2 × 10 15 Ω•cm and 17.69 kV/mm), respectively.

The influence of process parameters on the preparation of CaF2@Al(OH)3 composite powder via heterogeneous nucleation

Abstract The use of self-lubricating materials not only reduces friction coefficients and alleviates effects of wear and tear, but also helps to maintain the mechanical properties of materials. By using coating technology in the application of self-lubricating materials, it is possible to effectively improve the bonding strength between a solid lubricant and substrate material and additionally to protect the solid lubricant against oxidation and decomposition during the sintering process. This study uses the heterogeneous nucleation method, where aluminum hydroxide (Al(OH)3) is coated on the surface of calcium fluoride (CaF2) to prepare a CaF2@Al(OH)3 composite powder. It was observed, through analysis of the preparation process parameters, that the Al3+ concentration, pH value, and reaction temperature were the factors which most influence coating quality. Optimum process parameters were found to be an Al3+ concentration of 0.15 mol · L–1, pH value of 7.5, and reaction temperature of 75 °C. Comparing and analyzing the micro-morphology of sample composite powders proved the effectiveness and favorable performance of the CaF2@Al(OH)3 composite we produced under optimized process parameters.

Multiphase Field Modeling of Dendritic Solidification of Low-Carbon Steel with Peritectic Phase Transition

In the present study, an improved multiphase field model with taking into consideration the S/L interface anisotropy is proposed to simulate the dendritic growth with peritectic transition of low-carbon steel, and a new random heterogeneous nucleation method is proposed to treat the γ phase nucleation during the peritectic solidification process. The γ phase growth around the dendrite (the single dendrite and polycrystalline ferrite) and the subsequent peritectic transformation during the peritectic solidification are simulated. The results show that when the temperature reaches the γ phase nucleation temperature, γ nuclei suddenly nucleate at the δ/L interface, and laterally grow with the movement of L/γ/δ triple point around the δ/L interface of δ dendrite. After the δ dendrite is fully wrapped by the continuous intervening γ phase, the γ phase continues to grow with direct phase transformation from both δ phase and liquid phase. With the increase of melt undercooling, more δ phase and liquid phase are consumed to form γ phase, and the intervening γ phase between the δ dendrite and liquid phase becomes more and more thick, but the δ dendrite arm becomes more and more thin. During the dendritic solidification process, the solute would be rejected from dendrite trunk with the dendritic growth and enriched at the dendrite boundary, especially at the dendrite root. The solute enrichment at the dendrite root would inhibit the γ phase growth at the dendrite root and thus the thickness of intervening γ phase at the dendrite root is thinnest around the dendrite. Moreover, the solute concentration in γ phase is among the δ phase and liquid phase, because the carbon solubility in γ phase is higher than that in δ phase, but lower than that in liquid phase.

Mechanical properties, microstructure and crack healing ability of Al2O3/TiC/TiB2/h-BN@Al2O3 self-lubricating ceramic tool material

To prepare a self-lubricating ceramic tool with excellent mechanical properties and crack healing ability, the [email protected]2O3 solid lubricant with a core-shell structure was prepared by the heterogeneous nucleation method, and was added into Al2O3/TiC ceramic matrix together with TiB2. Examination of the micro-morphology and phase composition of [email protected]2O3 found that the surface of the solid lubricant h-BN was coated with Al(OH)3 at first, and after calcination at 1200 °C, a dense and uniform Al2O3 shell was formed. At the same time, the effects of the [email protected]2O3 addition on the ceramic tool material were studied. The mechanical properties of the ceramic tool material with [email protected]2O3 were improved relative to than those with h-BN. The optimal content of [email protected]2O3 solid lubricant was 5 vol%. In the friction and wear test, h-BN in [email protected]2O3 particles can be stripped to form a solid lubricating film on the material surface, which plays a good role in reducing wear and resisting wear. The crack healing ability of the self-lubricating ceramic tool material was studied by prefabricating cracks with a length of 400 μm on the surface. After a heat treatment at 700 °C for 60 min, the surface cracks of the ceramic tool material were completely healed, and the flexural strength was restored to 90% of that of the smooth samples. The oxidation of TiB2 and h-BN in ceramic tool materials is the main reason for crack healing.

Multi-Component Mesocrystalline Nanoparticles with Enhanced Photocatalytic Activity.

Mesocrystals, consisting of small subunits, have gained research interests owing to their ability to simultaneously modify material-specific properties and interactions among subunits. However, despite these unique characteristics, most mesocrystals are composed of a single material, and there is a disjunction between academic discovery and practical application. In this study, the synthesis of multi-component mesocrystalline nanoparticles composed of Fe3 O4 , ZnFe2 O4 , and ZnO subunits using a polymerization induced heterogeneous nucleation method is reported. The structure has small ZnFe2 O4 and ZnO nanocrystals covering the Fe3 O4 crystallites. It exhibits not only magnetic and catalytic properties determined by the size of each subunit nanocrystal, but also enhances photocatalytic and colloidal properties that originates because of its crowded arrangement. The magnetically recoverable catalysts exhibit remarkable photodegradation of organic molecules under the irradiation of visible light for 1 h; thus, improving its applicability in purifying a large amount of wastewater during the daytime.

Preparation of Mg(OH)2/Calcined Fly Ash Nanocomposite for Removal of Heavy Metals from Aqueous Acidic Solutions.

A magnesium hydroxide (MH)-modified calcined fly ash (CFA) nanocomposite (CFAMH) with core-shell structure was obtained with a heterogeneous nucleation method, and its application for removal of copper, zinc and nickel ions from aqueous acidic solution was studied. The microstructure and surface properties of CFA, CFAMH and MH powders were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller specific surface area (BET), X-ray diffraction (XRD) and Fourier translation infrared spectroscopy (FTIR), respectively. The preparation mechanism of CFAMH was discussed based on zeta potential and FTIR data. The results showed that nano-flake MH with thickness 13.4 nm was well coated on the surface of CFA. The specific surface area was increased from 2.5 to 31.0 m2/g. Si-O-Mg-OH bonds formed from the condensation of Si-OH and Mg-OH. The removal efficiency of heavy metals on CFAMH nanocomposite is higher than that of CFA and MH and follows an order of Cu2+ > Zn2+ > Ni2+. Solubility product constant (Ksp) is an important constant for the removal order of heavy metals on FA, CFAMH and MH. CFAMH nanocomposite can be a cheap material for removing heavy metal ions from acidic wastewater.

Preparation of nano - coating powder CaF2@Al(OH)3 and its application in Al2O3/Ti(C,N) self-lubricating ceramic tool materials

Nano CaF2 particles of different sizes were prepared by direct precipitation. The diameters of nano CaF2 particles prepared in mixed solvent can reach 5–7 nm, and can be effectively dispersed. The surface of nano CaF2 was modified and coated by heterogeneous nucleation method. A shell layer of Al(OH)3 was coated on the surface of nano CaF2, and the structure and coating mechanism of the coated powder were analyzed. Under varying preparation conditions, the surface morphology of CaF2@Al(OH)3 was analyzed using TEM and SEM. The results showed that the coating powder showed good dispersion in mixed solvents, and the particle size of the composite powder was about 20 nm. Self-lubricating ceramic tool materials were prepared by adding coating particles to the Al2O3/Ti(C,N) matrix. The coating powder shell and the matrix material melt during sintering, so that CaF2 forms nanostructures in the particles. thereby improving the mechanical properties of the material. Cutting experiments show that the addition of coating particles can effectively reduce the temperature, cutting force and friction coefficient in the cutting process of the tool, thus improving the cutting performance of the tool material.

Effect of c-BN surface modification on the microstructure and mechanical properties of (Ti,W)C-based cermet tool materials

Abstract Alumina-coated cubic boron nitride (c-BN) particles (c-BN@Al2O3) were prepared using a heterogeneous nucleation method. Then, they were added to a (Ti,W)C-based cermet tool material after synthesis via vacuum hot-press sintering. The microstructure and mechanical properties of the (Ti,W)C-based cermet tool material with varying c-BN@Al2O3 contents were recorded and analyzed. The results show that with increasing c-BN@Al2O3 concentration, the relative density, flexural strength, fracture toughness, and Vickers hardness all increase first and then decrease, and the average grain size first decreases and then increases. The introduction of Al2O3 into the c-BN particles used for surface modification can improve the wettability and interfacial bonding strength between the c-BN and matrix particles, restrain the grain growth of the matrix particles, and improve the flexural strength of cermet tool materials. The addition of c-BN@Al2O3 also alters the crack propagation mechanism of the cermet tool material and introduces multiple toughening mechanisms to improve the fracture toughness of the cermet tool material. The high hardness of c-BN and Al2O3 is the main reason for the increase in hardness; however, excessive addition of such material reduces the relative density, resulting in a decrease in hardness.

The surface electrical analysis of Nano Polyurethane-Based Superamphiphobic composite insulation materials

In the early stage of this study, it was found that Polyurethane was only two ways to construct the super-hydrophobic surface. The second is to construct micro-nano structure with low surface energy materials. Specific preparation methods of superhydrophobic surfaces include heterogeneous nucleation method, plasma treatment method, etching method, sol-gel method, vapor deposition method, electrochemical method, alternating deposition method, template method, self-assembly method, solve-non-solvent method, direct film formation method, etc., and many successful examples have been achieved. The research work in this field is relatively few, and the materials involved are scattered. The research objectives are all focused on the construction of micro-nano multistage surface structures with low surface energy. At present, most of these works only test the corresponding electrical properties of superhydrophobic surfaces. In order to verify the application prospect of superhydrophobic surface in antifouling flashover, it is necessary to carry out in-depth research on its hydrophobic, fouling and discharge aspects.

Preparation of Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 Ceramic Tools and Cutting Performance in Turning.

Aiming at the contradiction between the lubricating performance and mechanical performance of self-lubricating ceramic tools. CaF2@Al(OH)3 particles were prepared by the heterogeneous nucleation method. An Al2O3/Ti(C,N) ceramic tool with CaF2@Al2(OH)3 particles and ZrO2 whiskers was prepared by hot press sintering (frittage). The cutting performances and wear mechanisms of this ceramic tool were investigated. Compared with the Al2O3/Ti(C,N) ceramic tool, the Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 ceramic tool had lower cutting temperatures and surface roughness. When the cutting speed was increased from 100 m/min to 300 m/min, a lot of CaF2 was smeared onto the surface of the ceramic tool, and the flank wear of the Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 ceramic tool was reduced. The main wear mechanisms of the Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 ceramic tool were adhesive wear and micro-chipping. The formation of solid lubricating film and the improvement of fracture toughness by adding ZrO2 whiskers and CaF2@Al(OH)3 were important factors for the Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 ceramic tool to have better cutting performances.

Synthesis and Simulation of CaF2@Al(OH)3 Core-Shell Coated Solid Lubricant Composite Powder

In self-lubricating ceramic tools, adding CaF2 will significantly reduce the mechanical properties of ceramic tools. Based on heterogeneous nucleation theory, we have recently prepared aluminum hydroxide (Al(OH)3) coating on calcium fluoride (CaF2) through a liquid-phase heterogeneous nucleation method. By adding CaF2@Al(OH)3 coated powder to replace CaF2 powder, the self-lubricating ceramic tools maintain higher lubricity while also having better mechanical properties. The coating process was further confirmed by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, we used the molecular simulation software to simulate the suspension system of CaF2, Al(NO3)3·9H2O, and Al(OH)3 to study the process of Al(OH)3 coating on the surface of CaF2 particle to form CaF2@Al(OH)3 powders with core-shell structure. Further, the formation and evolution of Al(OH)3 molecules on the surface of CaF2 were analyzed.

Preparation and Characterization of Fly Ash Coated with Zinc Oxide Nanocomposites.

Calcined fly ash (CFA) was first obtained by calcining fly ash (FA) at 815 °C for two hours. Then, composite powders of CFA coated with zinc oxide nanoparticles (ZnO/CFA, ZCFA) were prepared by heterogeneous nucleation method. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Scanning electronic microscopy (SEM), Whiteness, and Brunauer-Emmett-Teller specific surface area (BET). Effects of pH value, reaction temperature and time, coating amount, solid-to-liquid ratio, the coating agent concentrations, and dropping speed on the whiteness of ZCFA powders were studied. It was shown that after coated with ZnO particles, the whiteness of CFA was increased from 27.0 to 62.6%, and the specific surface area was increased from 5.80 to 14.61 m2/g. Needle ZnO with the average grain size of 46 nm was deposited on the surface of CFA. Si–O–Zn–OH bonds were formed.

A nanocomposite consisting of an amorphous seed and a molecularly imprinted covalent organic framework shell for extraction and HPLC determination of nonsteroidal anti-inflammatory drugs.

A novel nanocomposite consisting of an amorphous seed and a molecularly imprinted covalent organic framework shell was prepared via a heterogeneous nucleation and growth method. By using ibuprofen as the dummy template, a molecularly imprinted covalent organic framework (MICOF) with a large surface area was prepared from 1,3,5-triformylbenzene and 4,4'-diaminobiphenyl. It was placed on the surface of monodisperse amorphous seeds. Owing to strong π-interaction, the MICOF@SiO2 nanocomposite displays fast binding kinetics, large adsorption capacities and selectivity for nonsteroidal anti-inflammatory drugs (NSAIDs). Following desorption from the MICOF@SiO2 with methanol containing 1% ammonium hydroxide, the NSAIDs ketoprofen, ibuprofen, diclofenac, indomethacin, flurbiprofen and naproxen were quantified by HPLC with UV detection. Under optimized conditions, the method exhibits good linearity within the range of 0.002-1.0μgmL-1, low limits of detection (0.38-2.92μgL-1), and acceptable repeatability. The recoveries of NSAIDs at three spiking levels range from 77 to 112%, and the RSDs are <9.4%. The method was successfully applied to the analysis of NSAIDs in spiked environmental water samples. Graphical abstract A molecular imprinted covalent organic framework nanocomposite (MICOF@SiO2) was prepared by heterogeneous nucleation and growth method. It was explored as a sorbent for the solid phase extraction of nonsteroidal anti-inflammatory drugs before determination by HPLC with UV detection.

Preparation and electrical properties of wollastonite coated with antimony-doped tin oxide nanoparticles

Abstract Composite antistatic powders of wollastonite coated with antimony-doped tin oxide nanoparticles (Sb-SnO2/wollastonite, SSW) were prepared by heterogeneous nucleation method. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Scanning electronic microscopy (SEM), Transmission electron microscopy (TEM) and Energy-dispersive X-ray spectrometry (EDS). Effects of pH value, hydrolysis temperature, coating amount, SbCl3 to SnCl4·5H2O molar ratio, calcination temperature and time on the resistivity of SSW powders were studied. It was shown that after coated with Sb-SnO2 particles, the whiteness of wollastonite has been decreased from 91.7 to 90.5, the specific surface area has been increased from 1.41 to 3.65m2/g, the volume resistivity has been reduced from 3.36 × 1010 Ω·cm to 0.85 × 105 Ω·cm. The fibriform wollastonite particles were coated with a layer of 30-50 nm thickness of well crystallized and uniform antimony-doped tin oxide (Sb-SnO2). A possible mechanism for coating of Sb-SnO2 nanoparticles on the surface of wollastonite fiber was proposed.