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21.
《International Journal of Hydrogen Energy》2022,47(80):34244-34256
A conducting and anticorrosive coating is crucial for the application of metal bipolar plates (BP) in proton exchange membrane fuel cell (PEMFC). In this work, a Ti3C2Tx (T)-carbon black (C)-acrylic epoxy (AE) coating is prepared on 304 stainless steel (SS) with enhanced corrosion resistance and conductivity. The corrosion resistance of the T-C-AE coating is investigated in a 0.5 M H2SO4 solution as compared to the AE, T, and T-AE coatings. The T-C-AE coated 304SS exhibits the strongest corrosion resistance with the most positive corrosion potential and the lowest corrosion current density of 0.00673 μA cm?2 in all the samples, while retaining intact and compact surface morphology with the lowest metal ion dissolution even after immersed for 720 h. The addition of Ti3C2Tx and carbon black into the AE matrix greatly decreases interfacial contact resistance (ICR), and the T-C-AE coating achieves a low ICR of 15.5 mΩ cm?2 under 140 N cm?2 compaction force. The excellent anticorrosion performance is mainly attributed to the physical barrier and the cathodic protection provided by the stacked Ti3C2Tx (MXene) nanosheets in the T-C-AE coating. This eco-friendly, conducting, and anticorrosive T-C-AE coating has a good application prospect on SS BP of PEMFC. 相似文献
22.
The dependence of the maximum and minimum wet thicknesses on the coating gap is derived for the slot-die coating process, under different slot-die configurations. Analytical expressions for the wet thickness and its derivative with respect to the coating gap are obtained using a simple flow model. The results indicate that, as expected, the minimum wet thickness increases linearly with the coating gap; however, the maximum wet thickness demonstrates a counterintuitive trend of decreasing as the coating gap increases, when a specific slot-die configuration is assumed. Moreover, the results are also validated by numerically solving the complete two-dimensional (2D) Navier–Stokes equation. 相似文献
23.
Giulia Andreani Enea Ferlizza Riccardo Cabbri Micaela Fabbri Elisa Bellei Gloria Isani 《International journal of molecular sciences》2021,22(1)
The recent introduction of the Asian yellow-legged hornet, Vespa velutina, into Europe has raised concern regarding the threat to honeybees and the competition with the European hornet, Vespa crabro. The aim of this study was to investigated essential (Mg, Fe, Zn, Cu) and non-essential (Cd and Pb) elements in these two species. Element concentrations were determined in the whole body and separately in the head, thorax and abdomen using atomic absorption spectrometry (AAS). The changes in essential element concentration and speciation during metamorphosis were also studied using size exclusion chromatography followed by AAS and proteomic analysis. In both species, the essential elements were more concentrated in the abdomen due to the presence of fat bodies. Magnesium, Fe and Zn concentrations were significantly higher in V. crabro than in V. velutina and could have been related to the higher aerobic energy demand of the former species required to sustain foraging flight. Low concentrations of Cd and Pb were indicative of low environmental exposure. The concentration and speciation of essential elements, particularly Fe, varied among the developmental stages, indicating a modification of ligand preferences during metamorphosis. Overall, the results in the present study provide a better understanding of the hornet metal metabolism and a foundation for additional studies. 相似文献
24.
The corrosion behavior of pure copper exposed to the atmosphere of Nansha Islands for 21 months was studied by mass loss method, composition analysis, morphology observation and electrochemical measurements. The results showed that the average corrosion rate of copper exposed for one year was approximately 7.85 μm/a, implying that Nansha Islands was classified as a corrosion category of CX. The structure and properties of the corrosion product layer generated on the front and back sides of the exposed sample differed significantly. The inner corrosion product layer (Cu2O) on the front side was relatively thick and dense, whereas the outer product layer (Cu2Cl(OH)3) was extremely thin. However, the outer product layer on the back side was thicker than the inner layer. Electrochemical measurements indicated that the protection afforded by the corrosion product layer on the front side was improved gradually, while that on the back side was deteriorated. 相似文献
25.
Poly(4-styrenesulfonic acid) (PSSA) doped polypyrrole (PPy)/tungsten oxide (WO3)/reduced graphene oxide (rGO) hybrid nanocomposite have been successfully synthesized using appropriate amounts of PSSA, pyrrole monomer, WO3, and rGO dispersed in aqueous solution through in situ chemical oxidation polymerization. Here, a simple spin coating method was used to fabricate a nitric oxide (NO) gas sensor composed of the aforementioned nanocomposite on a surface acoustic wave (SAW) resonator. This sensor can detect NO gas at concentrations of 1–110 parts per billion (ppb) at room temperature in dry air, with a sensitivity of 12 Hz/ppb and response and recovery times of <2 min. Moreover, its limit of detection (LOD) is 0.31 ppb for a signal to noise ratio of 3. It demonstrates repeatability, fast response, and recovery at room temperature. Moreover, its sensory performance remains highly stable over 30 days with only a 6.3% decrease in sensitivity. In addition, the sensor is highly selective for NO, even when nitrogen dioxide, ammonia, and carbon dioxide are applied as interfering gases. The inclusion of rGO (with large specific surface area) and the synergic effect of n-type WO3 nanoparticles in the p-type PPy matrix (leading to p-n heterojunction region formation) possibly underlie the efficient sensing performance of our sensor. 相似文献
26.
Although tremendous efforts have been made to ensure fresh produce safety, various foodborne outbreaks and recalls occur annually. Most of the current intervention strategies are evaluated within a short timeframe (less than 1 h), leaving the behavior of the remaining pathogens unknown during subsequent storages. This review summarized outbreak and recall surveillance data from 2009 to 2018 obtained from government agencies in the United States to identify major safety concerns associated with fresh produce, discussed the postharvest handling of fresh produce and the limitations of current antimicrobial interventions, and reviewed the intervention strategies that have the potential to be applied in each storage stage at the commercial scale. One long-term (up to 12 months) prepacking storage (apples, pears, citrus among others) and three short-term (up to 3 months) postpacking storages were identified. During the prepacking storage, continuous application of gaseous ozone at low doses (≤1 ppm) is a feasible option. Proper concentration, adequate circulation, as well as excess gas destruction and ventilation systems are essential to commercial application. At the postpacking storage stages, continuous inhibition can be achieved through controlled release of gaseous chlorine dioxide in packaging, antimicrobial edible coatings, and biocontrol agents. During commercialization, factors that need to be taken into consideration include physicochemical properties of antimicrobials, impacts on fresh produce quality and sensory attributes, recontamination and cross-contamination, cost, and feasibility of large-scale production. To improve fresh produce safety and quality during storage, the collaboration between researchers and the fresh produce industry needs to be improved. 相似文献
27.
《Ceramics International》2022,48(5):6208-6217
Three different coatings, namely TiAlN, TiAlN (external)/NbN (internal) and NbN (external)/TiAlN (internal), were deposited on cemented carbides by arc ion plating. The comparative investigation conducted in this study elucidates the effect of the NbN layer and coating systems on the growth, mechanical properties, and tribological performance of the coatings. The results showed that the surface of the TiAlN and TiAlN/NbN coatings was smoother when TiAlN served as the external layer. The NbN/TiAlN coating, wherein NbN formed the external layer, had a much rougher but more symmetrical surface. With the introduction of the NbN layer, the increased micro stress induced a lower adhesion strength in the TiAlN/NbN and NbN/TiAlN coatings. The TiAlN/NbN and NbN/TiAlN coatings exhibited higher hardness and hardness/effective elastic modulus (H/E*). During the friction test, when the temperature was elevated to 700 °C, the tribological performance of the monolayer TiAlN coating was the lowest because of the TiO2-induced breakage of the dense tribo-oxide film. The NbN layer participated in the formation of a NbOx film at elevated temperatures, which was responsible for the high tribological performance of the two bilayer coatings. When the NbN layer was on the outermost layer and in direct contact with the elevated temperature atmosphere, the NbN/TiAlN coating generated a tribo-oxide film with high integrity, and its coefficient of friction decreased by 27% of that at room temperature. Therefore, the NbN/TiAlN coating exhibited the highest wear resistance at 700 °C. 相似文献
28.
《Ceramics International》2022,48(6):7864-7875
Based on the ultrasonic C-scan results of 8YSZ coatings after thermal cycles, three-dimensional cylindrical numerical simulations of the physical geometry model of the thermal barrier coating (TBC) sinusoidal surfaces were conducted with finite elements to estimate the stress distribution and evolution law of the top coat (TC)/bond coat (BC) interface, including the centre and edge of the specimen affected by the dynamic growth of the thermally grown oxide (TGO). The results show that when a layer of TGO is grown on the TC/BC interface, compressive stress is uniformly distributed on the TGO interface, and the stress value decreases as a function of the TGO layer thickness. When the thickness of the TGO exceeds a certain value, the compressive stress of all parts of the interface gradually changes to tensile stress; meanwhile, the edges of the model affected by the crest and trough effects of the wave are reflected in the radial and circumferential directions, especially along the axial direction, with alternating concentrated tensile and compressive stresses. TGO growth imposes a minor influence on the magnitude and distributions of the radial and circumferential stresses at the BC interface. The linear elasticity, creep, fatigue, and stress accumulation effects of each layer of TBCs in each thermal cycle were fully considered in this model. The model not only interprets the crest and trough effects of the TC/BC surface interface during the growth of TGO, but also interprets the effects of the core and edge of the cylindrical model, further revealing the reason for which the core and edge of the TBC will most likely form cracks. 相似文献
29.
Bian Da Liu Yaxuan Aradhyula Thirumala Vasu Guo Yongxin Tang Hao Zhao Yongwu Wang Yongguang 《Ceramics International》2021,47(11):15722-15731
To enhance the tribocorrosion properties of chemically bonded phosphate ceramic coating (CBPCC), GO-ZnO was prepared and added into CBPCC. And the tribocorrosion behaviour of CBPCC was investigated. Results show that, with the introduction of GO-ZnO, the open circuit potential of CBPCC shifts in a positive direction and corrosion current density decreases. In addition, the total material loss, the total mechanical wear loss and the total electrochemical corrosion loss of CBPCC all decrease with the increase of GO-ZnO. The wear track of CBPCC after tribocorrosion without GO-ZnO is rough and porous, while the wear track becomes smooth and dense with the incorporation of GO-ZnO. The material in wear track is anchored by GO-ZnO due to the strong bond between GO-ZnO and CBPCC, which decreases the wear loss. Because of the extra force from the tribocorrosion experiment, the material anchored by GO-ZnO forms to a dense structure which prevents electrolyte diffusion into CBPCC. Moreover, GO-ZnO can block the electrolyte diffusion pathway and make it more tortuous. The resistance to the electrolyte diffusion decreases the corrosion current density and the increased wear loss due to electrochemical corrosion. 相似文献
30.