Xusheng Du

UV aging, corrosion and wear resistance of epoxy (EP) coatings are all critical for their long-term service in outdoor environments. In this work, graphene oxide (GO) was used as a multifunctional additive in epoxy coatings to improve these properties. Owing to its two-dimensional sheet-like nanostructure and abundant oxygen-containing functional groups, which enable a favorable interface with the epoxy matrix, incorporating GO into epoxy coatings endows the coating with multiple enhanced performances, including anti-corrosion performance, UV resistance, wear resistance, and adhesion to metal substrates. The resulting GO/EP composite coating exhibits higher adhesion strength (15.08 MPa) than that of neat epoxy coating (12.02 MPa), and delivers excellent corrosion resistance, with a corrosion current density of 4.69 × 10⁻¹¹ A·cm⁻² which is as low as 1/3 that of the neat epoxy coating after 25 days of immersion in NaCl solution. Notably, after multiple cycles of thermal cycling testing, the coating maintains an impedance ~40 times higher than that of neat epoxy coating. After UV aging testing, comparing to neat EP coating, the GO/EP coating experiences far less degradation in gloss, water resistance, corrosion resistance and bonding strength to steel substrates. In addition, tribological tests confirmed that GO/EP has improved wear resistance compared with neat epoxy coating and the wear rate of epoxy coating was reduced by ~30% with incorporation of only 0.1%wt GO. This study provides a promising strategy for developing durable protective coatings for practical applications.

In this work, a strategy for synergistic regulation of the Ti₃C₂T_x surface structure and redox activity of the electrolyte has been proposed. The surface modification of MXene was achieved via KOH treatment. Meanwhile, to cooperate with the surface-modified MXene electrode materials, Fe³⁺/Fe²⁺ was introduced into its common H₂SO₄ electrolyte to operate as a redox-active electrolyte for the first time. The results indicate that alkali treatment not only effectively reduces the amount of fluorine-terminal groups on the MXene surface but also forms in situ TiO₂ nanowires on its surface, thereby forming a unique hierarchical structure for facilitating the electrochemical reaction. Further utilization of the Fe²⁺/Fe³⁺ redox-active electrolyte introduced additional pseudocapacitive reactions at the electrode/electrolyte interface, significantly enhancing the capacitive performance of the system. This synergistic effect of both the hierarchical 1D TiO₂/MXene composite electrode materials and the redox-active electrolyte resulted in a substantial increase in specific capacitance from 78.17 F g⁻¹ to 655.54 F g⁻¹ at a current density of 10 Ag⁻¹. The reaction kinetics of the electrochemical systems were studied, along with their energy storage mechanism. It is revealed that there is a transition of the energy storage mechanism from being dominated almost solely by diffusion control to collaborative diffusion and surface reactions in the synergistic electrode/electrolyte system, and the corresponding equivalent circuit has evolved from the single-interface model to a dual-interface model. This work has demonstrated that the proposed synergistic strategy can effectively enhance the capacitive performance of the MXene energy storage system and can be applied to other electrochemical systems.

Hybrid fiber-reinforced polymer-laminated composites are often used under icy conditions (such as for reinforcing parts in aircraft frames and bridge beams), where there is an urgent demand for deicing. In this paper, besides the different mechanical properties of laminates along the longitudinal carbon fiber (CF) and glass fiber (GF) directions, the anisotropic electrothermal behavior of a hybrid glass/carbon fiber-reinforced epoxy (GCF/EP) is also investigated, as well as its deicing performance and self-repairing capability. The surface equilibrium temperature of GCF/EP composites can conveniently be adjusted by tuning the current magnitude and its flow direction. Compared to the longitudinal CF direction of the GCF/EP, where 0.3 A was loaded to achieve a surface equilibrium temperature of 122.8 °C, a much weaker current (0.03 A) was needed to load along the longitudinal GF direction to reach almost the same temperature. However, besides the higher flexural strength and fast temperature response, along the longitudinal CF direction, the GCF/EP exhibited excellent deicing performance, including a shorter time and larger energy efficiency. Furthermore, the self-repairing ability of the GCF/EP and its effect on the deicing performance of the composite were characterized. Studying the Joule heating effect of GCF/EP composite laminates and their corresponding deicing performance lays the foundation for their design and practical application in icy environments.

In this work, for surface protection of NiTi alloy, an amorphous carbon layer was directly deposited onto it via a self-catalytic flame coating method. The effect of the flame coating time on the physicochemical structure and mechanical hardness of the products was investigated, as well as its friction and wear resistance performance. The Vickers microhardness of the carbon-coated NiTi alloy decreased with the flame coating time, which was identified to be caused by the inherent thermal treatment during the flame coating process. The tribological test results indicated that both the friction coefficient (COF) and specific wear-rate of NiTi alloy were significantly reduced after the flame coating of the alloy. After direct flame treatment of the alloy for 20 min, 82.8% and 91.4% reduction in the COF and specific wear-rate could be achieved, respectively. The wear mechanisms of the coated NiTi alloy were found to be involved with the oxidation wear, adhesive wear, and the carbon transfer film, all of which had an important influence on the friction process. The carbon layer prepared by the flame coating method as a protective layer of NiTi alloy will greatly promote its versatile applications.

The synergistic effect of CNT and three-dimensional N-doped graphene foam (3DNG) on improving corrosion resistance of zinc-reinforced epoxy (ZRE) composite coatings was studied in this work. Although CNT itself was demonstrated to be effective to promote the anti-corrosion performance of the ZRE coating, the incorporation of additional 3DNG leads to further enhancement of its corrosion resistance under the synergistic effect of the hybrid carbon nanofillers with different dimensions. Both the content of the carbonaceous fillers and the ratio between them affected the performance of the coating. The optimal content of hybrid filler in the coating was determined to be only 0.1% with 3DNG:CNT = 1:3. With the modification of hybrid fillers, the corrosion current of the coating could be reduced by more than six orders of magnitude. Additionally, the immersion test of the pre-scratched coating directly demonstrated the evident contribution of the hybrid fillers to the sacrificial anode-based surface protection mechanism of the coating. These results confirmed the synergistic effect of the hybrid 1D and 3D carbonaceous fillers on promoting the corrosion inhibition of their coating, which could be promising for application in other functional composites.

Hybrid glass/carbon fiber (GCF) reinforced polymer composites are one of advanced composites with reduced cost, desired mechanical properties and special electrification performance. In the work, surface‐modified polypropylene (PP) non‐woven fabric was used as the interleaf for toughening these composites. The effects of the surface‐sulfonated PP fabric (PP/S) interleaves on various mechanical properties of the GCF reinforced epoxy (GCF/EP) composites were investigated firstly, including the mode II interlaminar fracture toughness and flexural strength. Comparing to the blank control sample, the G_IIC of the hybrid composites interleaved with the sulfonated PP fabric was increased evidently, as well as its flexural strength. These demonstrate the great interleaving effect of PP/S fabric on the GCF/EP laminated composites. Moreover, the heterogeneous electrically conductive behavior and electro‐thermal effect of GCF/EP interleaved with and without PP/S were studied. Interestingly, comparing to the control sample, the conductivity of the interleaved GCF/EP composites increased in both two in‐plane direction. Due to the hybrid character of the plain woven GCF fabric, both the temperature increase rate and the equilibrium temperature of the GCF/EP composites were much larger than that of pure carbon fabric reinforced composites under the same electrification condition.Highlights: Polypropylene fabric grafted with sulfonate group (PP/S) was fabricated. The tensile property of fabric almost unchanged after the sulfonation reaction. PP/S was more effective in toughening glass/carbon fiber/epoxy composite (GCF). PP/S increased the conductivity in in‐plane directions of the hybrid composites. GCF/EP displayed superior electro heating effect to CF/EP.

To improve the corrosion inhibition of zinc-rich epoxy (ZRE) composite coatings and shed light on the influence of the spatial structure of graphene fillers on the coatings’ performance, three-dimensional graphene (3DG) and a conventional graphene sheet (G) were used to modify the ZRE composite paint, respectively. The effect of introducing the 2D G fillers on the anti-corrosion behavior of ZRE was studied comprehensively, and its optimal content was determined to be 0.5 wt%. Interestingly, it was found that, comparing with 2D graphene sheets, the corrosion resistance of the ZRE coating could be enhanced more significantly with incorporating even less 3DG. With introducing only 0.1 wt% 3DG, the corrosion current intensity of the resulting 3DG/ZRE coating was reduced to be about 1/10 that of the G/ZRE coating with the same graphene content and 27% of that of the optimized G/ZRE. The corrosion products of the coating were analyzed with the XRD technique. The results indicated that, in contrast to neat ZRE coating, Zn₅(CO₃)₂(OH)₆ was absent from the corroded 3DG/ZRE coating, confirming its improved long-term anti-corrosion performance. The porous interconnected framework and high crystallinity of 3DG could contribute to not only its facilely mixing with epoxy resin, but also its effective incorporation into the conductive network of zinc micro-flakes, thus enhancing the corrosion resistance of its ZRE coating at a lower content. The innovative technology to improve the anti-corrosion performance of the ZRE coatings via using the 3D graphene fillers should be capable to be extended to other 2D fillers, such as MXenes.