In order to improve the emulsifying agent compatibility with epoxy resin, a series of nonionic waterborne epoxy emulsifiers with A-B-A (A is epoxy chain segment, B is hydrophilic chain segment) structure were synthesized by two-step method using polyethylene glycol (PEG6000, PEG4000, PEG2000), methyl hexahydrophthalic anhydride (MHHPA) and epoxy resin (E44) as raw materials. The structure of the emulsifier was characterized by infrared spectrum analysis, and the optimal synthesis process was determined by infrared spectrum analysis and acid titration: esterification reaction was carried out with PEG and MHHPA in the molar ratio of 1∶2.1 under the temperature of 110 ℃ for 3 h; then E44 in the same number of moles of MHHPA was added in and the epoxy ring-opening reaction was carried out under the catalyst tetrabbutylammonium bromide (TBAB, 1% of the amount of epoxy resin) at 110 ℃ for 3 h. Waterborne epoxy emulsion was prepared by using the synthesized emulsifier on epoxy resin E44. Then it studied the effects of relative molecular mass of PEG, emulsifier content, emulsifying temperature and stirring speed on the stability of the emulsion. After comprehensive consideration of emulsion stability, particle size and distribution, the results show that the emulsifier synthesized by PEG6000 has better emulsifying effect, with HLB value of 16.5 and turbidity point of 90 ℃, which is superior to PEG4000 and PEG2000. When the emulsion solid content is about 45%, the emulsifier content is 20%, emulsifying at 75 ℃ and stirring speed of 2 000 r/min, the water-based epoxy emulsion with small average particle size and narrow distribution can be obtained, and shows good emulsion stability.

At present, with the development of the energy field, the requirements for capacitors continue to increase. Capacitors with high temperature performance and high energy storage have become a research hotspot. High energy storage density requires high dielectric constant and low dielectric loss. The special engineering material polyimide (PI) is favored by people because of its high temperature resistance, but its low energy storage density restricts its application. In order to make better use of the high temperature resistance of polyimide and find an excellent synthesis route from the diversity of its synthetic raw materials, this paper aimed to prepare polyimide (PI) with high dielectric constant and low dielectric loss, and study the effect of isomer 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) and 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) on the dielectric properties of polyimide. Using a-BPDA, s-BPDA, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 4'-bis (3-aminophenoxy) diphenyl sulfone (m-BAPS) as raw material, PI film was prepared by ternary copolymerization, so as to verify the feasibility of the scheme. On this basis, the proportion of raw materials was allocated to explore the best performance of various raw material ratios. The films were characterized by FTIR analysis, XRD analysis, thermal performance analysis and dielectric performance analysis. The experimental results show that a-BPDA, s-BPDA, BTDA and m-BAPS can successfully synthesize polyimide films. The synthesized films still have high thermal properties. a-BPDA and s-BPDA increase the glass transition temperature of polyimide to 245.8 ℃ and 239.1 ℃, respectively. s-BPDA and a-BPDA have different effects on the dielectric properties of polyimide. When the ratio of s-BPDA to BTDA is 3∶2, the dielectric constant of sPI was 4.25 and the dielectric loss is 0.002 9 at 1 000 Hz. When the ratio of a-BPDA to BTDA is 3∶2, the dielectric constant of aPI is 3.49 and the dielectric loss is 0.002 3. Under comprehensive comparison, s-BPDA is more effective in improving the thermal and dielectric properties of polyimide.

In order to study the high temperature and deformation resistance of laser cladding coating on TC4 surface, different proportions of nickel-metal-multi-ceramic composite coatings were prepared on TC4 matrix by laser cladding technology. And GH4169 nickel-based superalloy powder was taken as the base powder, HfC, ZrC, TaC and NbC transition carbides as the reinforcing phase. The microstructure, hardness and high temperature deformation resistance of coatings with different multi-component ceramic powder contents were systematically studied by microstructure characterization and performance experiments. The results show that the addition of carbide ceramic reinforcement phase refines the microstructure of the coating and improves the hardness, and the hardness is the highest when the proportion of ceramic reinforcement phase is 15%, which is 2.54 times that of the substrate. With the increase of temperature, the internal dendrites of the pure nickel-based cladding coating were dissolved and separated, and gradually isoaxed. The dendrite fragmentation appeared in the nickel-based cladding coating supplemented with 15% ceramic powder, and the ceramic strengthened phase dispersed in the cladding layer gathered and grew. Under the conditions of three temperature compression test temperatures (700, 800 and 900 ℃), the maximum equivalent stress and maximum equivalent strain of the specimen appear in the matrix, and compared with the TC4 specimen, the laser cladding specimen produces a stress abrupt change in the coating bonding zone, and the deformation resistance ability of the laser cladding specimen coating is enhanced.

The recovery, storage and reuse of low-temperature waste heat in industry by using phase change materials for heat storage is an important method to achieve the gradual utilisation of energy and improve the efficiency of energy utilisation. The physical properties of phase change materials are the key factors determining the performance of heat storage systems.Therefore, the development of phase change materials with an appropriate phase transition temperature and good thermal cycling stability is of great significance for achieving efficient waste heat recovery. Based on this, a new phase change material, NaNO₃-KNO₃-NaNO₂-LiNO₃, was synthesized using the static melting method. A series of characterizations were conducted to evaluate its thermal properties, including melting point, latent heat, specific heat capacity, and cyclic stability, using differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, and Fourier transform infrared spectroscopy. The optimal composition was identified as m（NaNO₃）∶m（KNO₃）∶m（NaNO₂）∶m（LiNO₃）=6.32∶47.83∶36.10∶9.75 which was selected as the final preferred salt. The experimental results demonstrate that the preferred salt has significant performance advantages, with a low melting point of 79.02 ℃ and a latent heat of phase transition of 176.71 J/g; the average specific heat capacities of the solid and liquid phases are 1.96 and 2.09 J/(g·℃), respectively; the decomposition temperature reaches more than 600 ℃, which demonstrates its wide applicability in terms of temperature; after 100 high and low temperature cycling tests, the preferred salt still exhibited good thermal cycling stability. This study provides a new type of phase change energy storage material for low and medium temperature waste heat recovery and heat storage system, which is of great significance for energy optimisation and energy saving and emission reduction in related fields.

Due to the susceptibility of TC4 material to oxidation failure in high-temperature environments, its service life is significantly shortened under harsh conditions such as high temperatures and marine environments. To augment the high-temperature oxidation resistance of TC4 material surfaces, this paper employed laser cladding technology to prepare a high-temperature oxidation-resistant cladding coating with a gradient mass fraction of additive phases on the TC4 surface. The microstructure of the coating was observed using scanning electron microscopy (SEM), and the impact of the additive phase on the microstructure morphology of the cladding was analyzed. Subsequently, microhardness tests were performed to obtain the microhardness distribution of coatings with different material compositions, and the effect of additive phase content on the microhardness of the cladding was analyzed. Ultimately, macroscopic morphology observation, oxidation kinetics, SEM, and XRD methods were employed to evaluate the high-temperature oxidation resistance of the cladded samples after high-temperature oxidation tests. The effects of ceramic phase content and the high-temperature oxidation process on the microstructure and phase composition of the cladding layer were analyzed, and the oxidation resistance mechanism of the coating was explored. The experimental findings reveal that the incorporation of ceramic phase powders results in a marked improvement in the microhardness of the cladding layer, along with a refinement and densification of its microstructure. The dense oxide products formed during the high-temperature oxidation process effectively isolate the coating from the oxidizing environment, thereby substantially enhancing its resistance to high-temperature oxidation. The high-temperature oxidation product Ta₂O₅ formed on the surface of the cladding layer has a dense structure, strong high-temperature stability, and excellent oxidation resistance, which is the main reason for the improved high-temperature oxidation resistance of the ceramic phase-containing TC4 cladding layer.

To address the unclear effects of quenching-polishing-quenching (QPQ) treatment on the performance of nickel-aluminum bronze alloy coatings welded onto 27SiMn alloy steel, this study investigated the geometric characteristics, microstructural changes, corrosion resistance, and hardness of the copper alloy coating. The influence of the QPQ treatment process on the coating’s microstructure and properties was analyzed to verify the rationality and feasibility of this composite anti-corrosion technology. The results indicate that after undergoing the two processes of carbonization/nitriding and oxidation, the copper alloy coating forms a dual-layer infiltration structure, with metal carbides distributed across both layers and copper oxides concentrated near the surface, providing corrosion protection. Before and after QPQ treatment, the microstructure of the copper alloy coatings primarily consists of the matrix phase α, the metastable phase, and various κ phases dispersed within the α phase. High-and medium-temperature tempering leads to the precipitation of a large amount of β' phase into the α phase, causing the matrix phase to coalesce and expand while reducing overall hardness. According to the protection rating representation method based on the proportion of substrate area affected by corrosion, the protection rating of the surface of the copper alloy coatings layer samples is 9, while the copper alloy samples after QPQ treatment is 10. The corrosion resistance of the copper alloy surface after QPQ treatment is not only maintained but also exceeds that of the untreated one. In light of this, the composite anti-corrosion technology can be applied to the maintenance and remanufacturing of hydraulic bracket cylinder barrel parts, which can enhance the corrosion resistance of the inner wall of the cylinder barrel as a whole, while also considering the corrosion resistance of other parts such as the joint holes and the outer surface of the cylinder body.

Aluminum matrix composites have the characteristics of high hardness and difficult machining. In order to achieve near-net forming of aluminum matrix composites with high specific strength and high specific modulus, micron SiC particles with volume fraction of 10% reinforced AlMgScZr composites were fabricated using selective laser melting (SLM) technique. The relationship between the laser energy density and scanning rate and the forming quality of the composite was established. The microstructure and mechanical properties were characterized and tested by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and universal testing machine. The effect of micron SiC particles on the solidification structure and mechanical properties of SLMed aluminum matrix composites was investigated. The results show that the best quality composite could be obtained under the conditions of layer thickness of 30 μm, scanning spacing of 0.12 mm, laser power of 260 W, scanning rate of 1 000 mm/s, and its relative density was up to 99.81%. During the laser cladding process, there was a strong interfacial reaction between SiC particles and Al matrix. Micron-sized acicular Al₄SiC₄ bands were formed in situ, and the sharp corners of SiC particles are obviously passivated. Al₄SiC₄ bands and the residual SiC particles formed a mixed reinforced structure. The optimal tensile strength, elongation and elastic modulus of aged SiC/AlMgScZr composites were 379 MPa, 12% and 84 GPa, respectively. The fracture behavior of the composites included ductile fracture of Al matrix and brittle cleavage fracture of Al₄SiC₄ phases. A large number of cross-distributed acicular Al₄SiC₄ bands were the main factors leading to premature failure and fracture of SiC/AlMgScZr composites.

3D printed concrete is a promising new construction technology with potential applications in military field. As a prerequisite for its application in the military field, 3D printed concrete should possess strong impact resistance, providing reliable protection for military equipment and personnel. Currently, experimental research on the impact resistance of 3D printed concrete is limited by cost issues. Therefore, the use of numerical simulation technology can improve research efficiency, reduce costs, and better reflect the failure processes and damage conditions of 3D printed concrete. However, current numerical simulation technologies for 3D printed concrete do not take into account its unique interface structure, and thus fail to fully reflect the mechanical properties of 3D printed concrete. Based on the results of chloride ion penetration experiments, this study quantitatively characterizes the proportion of the interface region in 3D printed concrete. Using this as a basis, and in conjunction with previous mechanical performance studies, a numerical simulation model for the penetration resistance of 3D printed concrete was established, and its failure behavior was further investigated. By comparing the numerical simulation results with penetration experiment data, it was found that the penetration depth error of the 3D printed concrete model is within 4%, demonstrating its high simulation accuracy. During the penetration process, the 3D printed concrete target exhibits a characteristic of damage concentration at the interface, with the energy absorption at the interface being greater than that in the non-interface regions. As the projectile velocity and target strength increase, the projectile may disintegrate during penetration, leading to a sudden reduction in penetration depth, which further affects the variation of projectile velocity during the penetration process. Measures such as interface reinforcement, improvement of the 3D printing process, and the addition of high-strength aggregates can effectively reduce the penetration damage depth of 3D printed concrete targets, thereby enhancing their penetration resistance.

To investigate the bonding mechanical properties between polypropylene fiber and concrete interface, this study analyzed the debonding process of the interface through single fiber pull-out microscopic mechanical experiments and numerical simulations. An in-situ scanning observation system was established using micro CT and a self-developed single fiber drawing device to observe the process of pulling out a single polypropylene fiber with indentation from the mortar matrix. The deformation fields of the interface between fiber and matrix was obtained with mechanically regularized global digital volume correlation, and the interface debonding was quantified by calcula-ting the relative displacement of the shared nodes between the fiber and the matrix. A 3D microscopic numerical model reflecting the true shape of fibers and matrix was established based on CT images, and the single fiber dra-wing process was simulated and analyzed. The results show that the force-displacement curves display multi-peak fluctuations corresponding to the fiber geometry after the peak. The strain fields at interfaces measured by digital volume correlation and numerical simulation show a strain concentration phenomenon related to the geometric shape of the indentation fiber, indicating that the periodic indentation of the fiber increases mechanical interlocking and friction forces between the fiber and the matrix during pullout. The relative displacement at the interface is greatest and decreases along the fiber’s axial direction. In the horizontal direction, the variation of relative displacement was correlated with the geometric shape of the fiber. The relative displacement in the vertical direction reflected that the fiber and matrix have completely debonded before the pullout force reaches the peak load.

Chitosan (CS) and laponite (LAP) are both biocompatible materials, and modification can enrich them with enhanced bioactivity. This paper investigates the preparation of a composite antibacterial material based on quaternized chitosan (QCS) and modified lithium montmorillonite, as well as its antibacterial performance in shampoo applications. QCS was degraded via microwave-assisted hydrogen peroxide oxidation to enhance its solubility, and LAP was organically modified with cetyltrimethylammonium bromide (CTAB) to impart its Malassezia adsorption capability, resulting in positively charged organic LAP. The successfully prepared QCS and CTAB-LAP composite materials were characterized and validated using Fourier-transform infrared spectroscopy, Zeta potential analysis, rotational rheometry, and scanning electron microscopy. Experimental results demonstrate d that QCS with different molecular weights exhibits good antibacterial performance in aqueous media, and the composite material of QCS and CTAB-modified LAP significantly enhances the antibacterial effect through synergistic action. By optimizing the dosage and ratio of the antibacterial agents, the study identified the optimal formulation of the composite antibacterial agent for use in both aqueous media and base shampoo. QCS of various molecular weights demonstrated excellent antimicrobial performance in aqueous media. The QCS and CTAB-LAP composite material exhibited a synergistic enhancement in antimicrobial effect. Optimal formulations for the composite antimicrobial agents in aqueous media and base shampoo were identified by varying the amount and ratio of the components. In aqueous solution, composite mixtures with mass ratios of 9∶1, 5∶5, and 1∶9 achieved 100% antimicrobial efficacy after 10-fold dilution and 5 minutes of Malassezia strain contact. When added to base shampoo at a 9∶1 ratio (total mass fraction 0.14%) and diluted 100-fold, the composite maintained significant antimicrobial efficacy, reaching up to 70% effectiveness compared to commercial chemical anti-dandruff products. This study highlights the potential of the QCS and CTAB-LAP composite for practical application in anti-dandruff shampoos and paves the way for the development of natural and eco-friendly antimicrobial materials.

The issue of water pollution is becoming increasingly severe, highlighting the urgent need to develop efficient and sustainable methods for pollutant removal. This study proposed the use of ambient pressure drying to prepare a nanocellulose-based aerogel with high adsorption capacity for both anionic and cationic pollutants. Polyethyleneimine (PEI) was first attached to a carboxymethylated cellulose nanofiber (CNF) framework through electrostatic interactions. Then, γ-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA) were used for chemical crosslinking to form a hydrogel. Finally, through solvent exchange and ambient pressure drying, a low-density (18.80 mg/cm³) and high-porosity (92.06%) CNF/PEI composite aerogel (CPA) was obtained. This aerogel demonstrated excellent structural stability in water. Owing to the coexistence of anionic carboxymethyl and cationic amino groups, the aerogel exhibited strong adsorption capacity of aerogel per gram for both cationic and anionic dyes in complex wastewater environments. The maximum adsorption capacities of aerogel per gram for methylene blaue (MB) and Congo red (CR) were 516 mg and 2 090 mg, respectively,with removal rates of over 98% for both anionic and cationic dyes. In addition, the aerogel exhibited good structural stability and fatigue resistance. After soaking in an alkaline solution for a week, it remained intact, and after 10 cycles of compression in the wet state, its elasticity recovery rate remained at 60%. Compared to similar adsorption materials, CPA shows significant advantages in terms of adsorption capacity, amphoteric adsorption ability, and reusability. The preparation method proposed in this study is time-efficient and highly effective, making it suitable for large-scale production, with promising potential for application in industrial wastewater treatment.

During the production of manufactured sand, a large amount of stone powder was sieved and buried, leading to resource waste and environmental pollution. To improve the utilization rate of manufactured sand stone powder, this study explores the high-value application of waste stone powder in concrete. By treating the stone powder in manufactured sand as a cementitious component to partially replace cement, the effects of granite stone powder on the microstructural evolution of hardened cement paste were investigated using XRD, TG, SEM, and other characterization methods, leading to the identification of the optimal cement replacement range. Furthermore, by adjusting the stone powder content in manufactured sand, coarse aggregate gradation, sand ratio, and water-to-binder ratio, the workability and mechanical properties of concrete were optimized. The study reveals the mechanism by which paste volume fraction influences concrete’s workability and mechanical performance, and successfully produced low-cost concrete with acceptable workability and mechanical strength using manufactured sand with a high stone powder content. The results show that cement paste with 10% stone powder retained a denser microstructure, as the amount of hydration products showed negligible reduction compared to that of pure cement paste after 7-day and 28-day curing. However, when the substitution of cement with stone powder exceeded 20%, the amount of hydration products decreased significantly by more than 20%, leading to a porous microstructure and lower compressive strength compared to that of pure cement paste. When manufactured sand (MS) with high stone powder content is used in concrete production, the dosage of superplasticizer needs to be increased slightly under the same slump requirement. Additionally, the optimal workability and mechanical properties of MS concrete were achieved when the volume fraction of paste lay in the range of 31~32%. Consequently, C30, C40, and C50 concretes meeting target property requirements were prepared using MS with 15.1%, 16.5%, and 18.7% stone powder content, respectively, resulting in cement consumption reductions of 54, 63, and 92 kg/m³, and thereby significant reductions in cost and carbon emissions.

To reveal the influence mechanism of coarse aggregate profile characteristics on the meso-mechanical properties of asphalt mixtures, this study employed digital image processing technology to obtain the profile characteristics of coarse aggregates and constructed discrete element models of coarse aggregates with multiple morphological features. Combined with a virtual uniaxial penetration test system, the impact of aggregate geometry on the meso-mechanical response of asphalt mixtures was investigated. The results indicate that a mixed tensile-compressive stress mode exists at aggregate contact points, with compressive stress accounting for 40%~50%, tensile stress for 10%~20%, and mixed stresses for 30%~40% of the total. The application of uniaxial penetration load leads to rapid growth in microcrack numbers. In mixtures with higher elongated and flat aggregate content, microcracks at the aggregate-asphalt interface connect more readily to form through cracks, whereas mixtures with higher cubical aggregate content exhibit smaller microcrack distribution areas and lower stress levels. Microcracks are mainly induced by shear stress, accounting for about 90% of total microcracks; the number of microcracks caused by tensile stress is relatively small, accounting for about 10%. The maximum microcrack length reaches 10 mm, while the minimum is approximately 0.2 mm. For mixtures rich in cubical coarse aggregates, skeleton interlocking effectively resists loading. These findings provide theoretical support for coarse aggregate selection in asphalt pavement construction and quality improvement in aggregate processing.

The traditional process of new material development, heavily reliant on extensive experimentation and empirical knowledge, suffers from low efficiency, prolonged cycles, and high costs. Integrating efficient experimental techniques with rapid computational simulation and prediction through intelligent methods can significantly shorten the R&D and engineering application cycle while reducing costs. Chopped basalt fiber-reinforced polylactic acid (BF/PLA) composites, being naturally green, environmentally friendly, and biodegradable, represent an ideal alternative material for automotive interior and exterior components with considerable development potential. In order to study the influence of different fiber parameter ratios on the thermal properties of BF/PLA composites and facilitate rapid development of suitable automotive component materials, this study first conducted experiments on the thermal properties of BF/PLA composites under various fiber parameter ratios. Through data correlation analysis, the effects of different fiber parameter ratios on composite thermal properties were examined. Using F-values from three-factor ANOVA, a fiber parameter quasi-centralization method was proposed, establishing fitted regression functions between glass transition temperature/crystallinity and centralized variables. Based on these regression functions and polynomial guiding functions, new ratios of fiber mass fraction, diameter, and length parameters were incorporated to obtain centralized variables for glass transition temperature and crystallinity under the new parameter ratios. The glass transition temperature and crystallinity of BF/PLA composites with new parameter ratios can be obtained by fitting regression function, and the thermal properties of composites with more fiber para-meter ratios can be predicted by fitting regression function, and the determination coefficients are 0.887 0 and 0.855 1 respectively, with prediction accuracy within practically acceptable engineering ranges. Finite element analysis of thermal performance for a vehicle door inner panel demonstrated slightly superior thermal properties using the optimized composite material selected through the proposed method, along with significantly improved R&D efficiency, validating the effectiveness of the approach. This provides important theoretical guidance and methodological reference for rapid development, cost reduction, material substitution, and green design of future automotive composites.

To address the limitations of traditional models in cross-laboratory validation, this study proposes a chloride diffusion coefficient model for concrete that incorporates a cement type factor, accounting for the influence of cement type and strength grade. The model is developed through regression analysis of multi-source large-sample Rapid Chloride Migration (RCM) test data. Firstly, a comprehensive database of 179 RCM test datasets from 70 laboratories was established to analyze the effects of water-binder ratio, cement type, and strength grade on the chloride diffusion coefficient via regression. Furthermore, the cement type factor was introduced into the computational model using a two-phase regression method, and its value was determined based on the multi-source large-sample data. Finally, comparative analyses with traditional models and validation using independent test data were conducted. The results show that the proposed multi-source large-sample model improves the fitting accuracy to experimental data by 19.6% compared to conventional mono-source small-sample models. The cement type factor effectively captures the combined influence of cement type and strength, reducing the weighted average error and coefficient of variation by 32.0% and 25.0%, respectively, thereby significantly enhancing the model’s predictive precision and adaptability.