Research into the application of protective titanium beryllide coatings in thermonuclear devices and high-temperature structures is currently of great interest. However, the harsh operating environments of thermonuclear devices impose severe thermal loads, causing rapid oxidation and degradation of structural materials like stainless steel. While titanium beryllide serves as a promising high-temperature alternative to pure beryllium, its long-term corrosion behavior and structural stability under extreme thermal conditions remain insufficiently understood. This paper presents the results of a study of titanium beryllide protective coatings under high-temperature corrosion testing conditions. Titanium beryllide coatings were applied to a stainless steel substrate using DC magnetron sputtering. Isothermal oxidation in air was used to determine the corrosion resistance of the coated steel. Test temperatures were 700, 900, and 1100 °C. Testing and subsequent studies of coating and substrate degradation demonstrated that titanium beryllide coatings effectively protect the substrate material from high-temperature oxidation. Moreover, the mechanism of coating structure transformation changes with increasing temperature. The interdiffusion of substrate and coating elements allows for an extended protective effect of the coatings.
Icing on wind turbine blades affects power-generation efficiency. Therefore, it is crucial to provide ice protection for wind turbine blades. This paper investigates how ambient temperature and liquid water content affect the formation and downstream evolution of runback ice during electrothermal de-icing of a wind turbine blade airfoil by numerical simulation. A coupled numerical model integrating external airflow, droplet collection, ice accretion, and unsteady heat conduction is established based on FENSAP-ICE. The simulated temperature agrees well with the experimental data, with an absolute maximum error of 2.02 K and an RMSE of 1.75 K, indicating that the model accurately captures the transient thermal response of the electrothermal de-icing system. The results indicate that after 20 s, the leading-edge ice completely disappears at 268 K, while 0.21 mm of residual ice remains at 258 K. Over the investigated LWC range of 0.5–1.5 g·m−3, a change in trend is observed: the runback ice thickness does not increase proportionally with LWC, suggesting that local freezing capacity may become increasingly important at higher LWC. Furthermore, the freezing front is not stationary but migrates continuously downstream as ambient temperature increases and de-icing proceeds, and the migration rate is higher in the 263–268 K range than in the 258–263 K range. These findings provide qualitative insight for anti/de-icing strategy.
Natural aggregate concrete is prone to crack propagation and overall crushing under impact load, making it difficult to satisfy the service requirements for collapse resistance in building structures. In order to improve the impact resistance of concrete, this study investigated the impact of the mechanical behavior of steel-polypropylene hybrid fiber-reinforced concrete (SPFRC) using a split Hopkinson pressure bar apparatus. The effects of steel fiber content, polypropylene fiber content, and strain rate on the fractal dimension were examined, and the relationship between total energy dissipation and fractal dimension was established. The results show that the mean fragment size of the crushed specimens decreases linearly with increasing driving voltage, whereas it increases with fiber content. The fractal dimension monotonically increases with an increasing strain rate and decreases as the fiber content increases. Under a driving voltage of 1200 V and steel fiber content of 0.5%, increasing the polypropylene fiber content from 0% to 0.1% yields the largest reduction in the fractal dimension (15.00%) for specimen S0.5P0.1, exceeding the reductions from increments of 0.1%-0.25% and 0.25%-0.5%. Comparative results demonstrate that SPFRC exhibits superior impact failure resistance compared with concrete reinforced by a mono type of fiber. Exploring the correlation between fractal features and total energy dissipation can realize a more systematic and comprehensive performance assessment of concrete materials. The research results can provide quantitative theoretical support for the impact resistance evaluation and ratio optimization of SPFRC.
This study used silicate cement as the base material and nano-silica, fly ash, and bentonite as the composite modification components. Through laboratory tests, the engineering characteristics and impermeability and drying shrinkage properties of the modified slurry were systematically investigated. The results showed that the verification test mix proportion of the slurry was a water-binder ratio of 0.7, a nano-silica content of 2%, a fly ash content of 40%, and a bentonite content of 6%. This ratio of the slurry had the best comprehensive performance. Compared with pure cement slurry, the water loss rate decreased by 61.90%; the 3d, 7d, and 28d compressive strengths increased by 30.60%, 36.08%, and 20.08% respectively; the fluidity decreased by 6.38%; and the initial setting time decreased by 9.77%. The anti-seepage pressure of the verification test mix proportion slurry group reached 1.05 MPa, which was 43.84% higher than the pure cement reference group and was superior to each single addition group. Combined incorporation of nano-silica, fly ash, and bentonite remarkably improved the impermeability. The 56d drying shrinkage rate was 1257 & times; 10-6, which was 19.16% lower than that of the reference group. Based on X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests, the microstructure was analyzed, and the hydration mechanism was discussed. The composite modification did not change the type of hydration products but significantly improved the microstructure. Nano-silica reacted with the hydration product Ca(OH)2 in the early stage of hydration, accelerating the hydration process and promoting the interwoven coating of the hydration product on the calcium aluminosilicate crystals, thereby improving the compactness of the matrix. Fly ash participated in the pozzolanic reaction in the later stage of hydration, adhering to the secondary hydration products on the surface and gradually consuming them, further filling the pores and optimizing the interface structure. Combined with bentonite, nano-silica and fly ash jointly densified the matrix, refining the microstructure of modified samples and forming a continuous integrated hydration product network inside the grout.
Infection associated with orthopedic implants remains a major challenge in the development of biomimetic materials for bone tissue engineering. Surface modification strategies are widely employed to transform bioinert metallic substrates into bioactive interfaces that promote tissue integration while preventing bacterial colonization. This study investigated the effect of incorporating silver nanoparticles (nAg) into hydroxyapatite-barium titanate (HA-BT) coatings on their structural, mechanical, piezoelectric, biological, and antibacterial properties. Raw materials were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), whereas coatings were evaluated by XRD, scanning electron microscopy (SEM), tensile adhesion testing, electrochemical analysis, piezoresponse force microscopy (PFM), cell viability, and antibacterial assays. The coatings exhibited secondary phases, including beta-tricalcium phosphate (beta-TCP), tetracalcium phosphate (TTCP), and calcium oxide (CaO), generated during atmospheric plasma spraying (APS), while no silver oxide phases were detected after nAg incorporation. SEM observations revealed homogeneous phase distribution and strong coating-substrate adhesion. The addition of nAg did not significantly affect adhesive strength (44.58 +/- 2.2 MPa for HA30BT and 43.28 +/- 2.8 MPa for HA30BT-nAg). Protein adsorption studies indicated moderate albumin affinity (Kads = 0.45) for nAg-containing coatings. Both coatings exhibited piezodynamic activity with d33 values of approximately 13 pm/V. MTT assays confirmed non-cytotoxic behavior, with viability reductions below 2%. Osteocalcin expression demonstrated comparable osteogenic activity in coatings with and without nAg, regardless of low-intensity pulsed ultrasound stimulation. These findings highlight the potential of HA-BT-nAg coatings as multifunctional surfaces for bone regeneration and infection prevention.
