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1.
The gas diffusion substrate (GDS) is essential in the proton exchange membrane fuel cells. Its fabrication techniques affect the performance significantly and are worthy of investigation. In this study, a manufacturing process of the GDS is proposed to understand the formation process of GDS and promote its structure and performance more pertinently. Different states during the preparation process, raw carbon paper, pre-curing, curing, carbonation, and graphitization, are characterized and measured. Experimental and numerical methods are employed to determine the relationships between microstructure, transport, and mechanical performance variation with the fabricating processes. The results show that its porosity, average pore size, and effective diffusivity decrease first and increase after curing. These parameters after graphitization are lower than that of the carbon paper (CP). The electrical resistivity increases dramatically while pre-curing and decreases gradually after curing, carbonation, and graphitization, and it is much reduced after graphitization. Moreover, mechanical measurement results show that both the picks of tensile strength and flexural modulus occur after curing. Its tensile strength shows little change after graphitization compared to the initial paper's. In contrast, the flexural modulus is improved significantly.  相似文献   
2.
Adsorbents and membranes consisting of carbon nanotube (CNT) pores with diameters of molecular dimensions are highly desirable for hydrogen storage and selective, high-flux membrane separation. However, fabrication of such materials with precise pore sizes and monodispersity as well as evaluation of the mechanisms associated to adsorption and molecular transport are challenging. Herein, we grew aluminophsphate zeolites (CoAPO-5, AFI crystal structure) consisting of one-dimensional, monodisperse parallel pores with diameter of ~7 Å, and utilized them as templates to grow singe-walled CNTs (SWNTs) inside the pores. The resulting materials were examined as adsorbents and membranes for hydrogen storage and separation, respectively, using single-gas and real mixture feeds. Detailed mechanistic analysis and fundamental investigation of permeance and adsorption behavior of the resulting CNT-in-zeolite systems via combined adsorption, equilibrium, and kinetic studies were carried out. A superior gravimetric hydrogen uptake of 1.2 wt% at 35 °C and 1 bar was achieved in the case of the SWNTs grown in the cobalt-richer AFI host. Permeability measurements were performed on the respective Co(x)APO@SWNT membranes with the Co-richAPO@SWNT membrane exhibiting the highest permeance for all studied gases as a consequence of larger and more densely packed AFI crystals along with higher number of SWNT-filled pores, assets attributed to the higher Co catalyst content. Notably, the produced composite membranes exhibited gas permeability values that were two orders of magnitude higher than what predicted by the Knudsen mechanism.  相似文献   
3.
Gas diffusion layer (GDL) is one of the most important components of fuel cells. In order to improve the fuel cell performance, GDL has developed from single layer to dual layers, and then to multiple layers. However, dual or multi layers in GDL are usually prepared by layer-by-layer methods, which cost too much time, energy, and resources. In this work, we successfully developed a facile one-step method to prepare a GDL with three functional layers by utilizing the different sedimentation rates and filtration rates of short carbon fiber (CF) and carbon nanotube (CNT). The treatment temperature for this GDL is much lower than that of traditional method. The thickness of the GDL can be effectively controlled from as thin as 50 μm to more than 200 μm by simply adjusting the content of CF. The GDL with high flexibility is suitable to develop high performance flexible electronics. The fuel cell with the GDL has the maximum power density 1021 mW cm?2, which shows 19% improvement comparing to the conventional one. Therefore, this work breaks the traditional concept that GDL for fuel cells only can be prepared by very complex and high-cost procedure.  相似文献   
4.
以碳纳米管(CNT)作为核,密胺树脂(MF)作为壳,苯乙烯马来酸酐共聚物(SMA)为乳化剂,原位聚合制备微胶囊化碳纳米管(CNT-MF),并将包覆后的碳纳米管作为填料添加到硅橡胶泡沫中,制备了CNT-MF/硅橡胶泡沫复合材料。探讨了核/壳质量比对微胶囊化碳纳米管的包覆效果的影响,同时研究了微胶囊化碳纳米管用量对硅橡胶泡沫泡孔结构和介电性能的影响。结果表明,微胶囊化碳纳米管的加入有利于提高复合材料的泡孔结构,大泡孔的存在和泡孔面积有利于材料介电性能的提高。当核/壳质量比为1∶10的微胶囊化碳纳米管添加量为15 phr时,复合材料介电性能表现最佳,此时复合材料在1 kHz的介电常数为26.34,介电损耗仅为0.0136。  相似文献   
5.
李秋  姜雨杭  耿海宁  陈伟 《硅酸盐通报》2022,41(5):1805-1812
钢结构因具有多种优点而被广泛应用于工程建筑领域,但其在火灾高温环境下会丧失力学性能,造成结构失效,因此对钢结构进行防火保护成为关键。以偏高岭土、矿粉和憎水处理后的膨胀珍珠岩为主要原材料,模数为1.5的钾水玻璃为激发剂,制备非膨胀型钾基地聚物基防火涂料,并采用大板燃烧法研究该涂料在1 200 ℃下的防火性能;同时,对其在室温、1 000 ℃以及1 100 ℃热处理前后的力学性能、表观形貌、物相组成、微观结构演变进行了表征分析,探究地聚物在高温过程中的陶瓷化过程。结果表明:该防火涂料具有优异的防火能力,在1 200 ℃下进行2 h耐火极限试验后,钢板背面温度低于160 ℃;防火涂料在1 100 ℃高温热处理2 h后,抗压强度大幅增加至室温强度的5.8倍,达30.80 MPa;防火涂料基体的无定型地聚物相在800 ℃开始发生陶瓷化转变,1 100 ℃时生成的陶瓷相主要为钙长石、莫来石以及白榴石。  相似文献   
6.
采用铸膜法制备了一种羧甲基壳聚糖/氧化羧甲基纤维素/姜黄素(CMCHS/ OCMC/ CR)三元复合材料。红外光谱和扫描电子显微镜分析显示,复合膜断面结构均匀,无分层,但表面粗糙度有所增大。与不添加姜黄素相比,复合材料具有更好的断裂应力(20.10 MPa),断裂伸长率(18.97%),抗真菌性能(黑曲霉抑菌圈15.33 mm,青霉抑菌圈14.58 mm)和透水性(2.11×10-3 g·m-1·kPa-1·h-1)。草莓保鲜实验结果表明,CMCHS/OCMC/CR复合材料涂膜可减缓贮藏过程中的失重率和可滴定酸、可溶性固形物、还原糖含量的下降。经贮藏8 d,草莓失重率比较空白对照减少了11.38%,较阳性对照减少了1.27%,硬度,可滴定酸、可溶性固形物、还原糖含量的下降分别较空白对照减少了10.00%、42.72%、7.39%、9.32%,较阳性对照分别减少了5.54%、7.42%、2.39%、11.12%。因此CMCHS/OCMC/CR(1%, m/m)复合膜显示出良好护色和抑制霉菌生长的保鲜作用,可作为良好的涂膜抗菌材料应用于食品包装材料中。  相似文献   
7.
层状氧化物正极材料具有良好的结构稳定性和较高的充放电比容量,是一类理想的钠离子电池正极材料。本工作研究了层状氧化物正极材料NaNi1/3Fe1/3Mn1/3O2表面修饰对其电化学性能的影响,采用固相球磨法在正极材料表面包覆一层纳米ZrO2,采用形貌、结构、电化学方法等研究了包覆后性能改进机理。研究结果表明,ZrO2在NaNi1/3Fe1/3Mn1/3O2表面形成一层惰性保护层,有效隔开了电解液与正极材料的接触,缓解了电解液的分解速度,抑制了金属离子的溶出速度,从而显著改善了电池的循环性能以及高温性能。在ZrO2包覆修饰后,55℃下正极材料相比于未包覆的正极材料有明显提升,100次循环后容量保持率达到83.6%,高于未包覆的75.2%。此外,包覆后的NaNi1/3Fe1/3Mn1/3O2正极材料在空气环境存储后,稳定性得到明显提高。  相似文献   
8.
The introduction of catalyst on anode of solid oxide fuel cell (SOFC) has been an effective way to alleviate the carbon deposition when utilizing biogas as the fuel. A series of La0.6Sr0.4Co1-xNixO3-δ (x = 0, 0.2, 0.4, 0.6, 0.8) oxides are synthesized by sol-gel method and used as catalysts precursors for biogas dry reforming. The phase structure of La0.6Sr0.4Co1-xNixO3-δ oxides before and after reduction are characterized by X-ray diffraction (XRD). The texture properties, carbon deposition, CH4 and CO2 conversion rate of La0.6Sr0.4Co1-xNixO3-δ catalysts are evaluated and compared. The peak power density of 739 mW cm?2 is obtained by a commercial SOFC with La0.6Sr0.4Co0.4Ni0.6O3-δ catalyst at 850 °C when using a mixture of CH4: CO2 = 2:1 as fuel. This shows a great improvement from the cell without catalyst for internal dry reforming, which is attributed to the formation of NiCo alloy active species after reduction in H2 atmosphere. The results indicate the benefits of inhibiting the carbon deposition on Ni-based anode through introducing the La0.6Sr0.4Co0.4Ni0.6O3-δ catalyst precursor. Additionally, the dry reforming technology will also help to convert part of the exhaust heat into chemical energy and improve the efficiency of SOFC system with biogas fuel.  相似文献   
9.
针对垃圾焚烧炉受热面的高温腐蚀,分析了硫/氯协同作用对涂层高温腐蚀性能的影响,以期为未来涂层服役性能的提升提供理论指导,促进垃圾焚烧发电的发展。在实验室模拟气氛(体积分数95%)+O2(体积分数5%)条件下,对涂有Na2SO4盐、NaCl盐及NaCl+Na2SO4混合盐的TC4渗铝样品进行600 ℃的高温腐蚀实验,并利用扫描电镜(SEM)、能量色散光谱仪(EDS)和X射线衍射(XRD)等手段对试样进行了分析。结果表明:当喷涂Na2SO4溶液时,涂层表面发生微弱的腐蚀;当喷涂NaCl+ Na2SO4(质量分数比1:2)混合盐溶液时,在涂层表面生成了多层结构的腐蚀氧化层;当喷涂NaCl溶液时,涂层表面发生了严重的腐蚀,腐蚀产物主要是富含Al、Ti的氧化物和氯化物。在腐蚀过程中,氯化钠在高温下形成Cl-1,其穿透初期形成的氧化膜,随后生成的金属氯化物在高温下汽化,向外扩散到达表面氧分压较高的区域时又被氧化为金属氧化物,此过程连续循环,使表面的多层氧化膜不断被腐蚀,随着Cl-1浓度的增加样品的腐蚀更加严重,但S和Cl的协同作用可以降低涂层的腐蚀速率。  相似文献   
10.
The continuous roll-to-roll slot die coating technique has shown great potential for fuel cell electrode fabrication. It is essential to determine the particulate coating window to obtain a defect-free film of uniform thickness and uniform particle dispersion. For this dual-purpose, an additional upper operating limit has been proposed via a “flow field analysis scheme” that combines analysis and simulation. In this analysis, the fundamentals of flow pattern transition (Poiseuille–Couette–bubbly flow) behind coating limits are clarified. The Couette flow is advantageous for uniform shear rate and dispersion. Furthermore, phase-field simulations systematically investigate the effect of fluid and geometrical parameters and quantitatively present the flow limit with explicit expression. Results reveal that the slope of the upper limit is inversely correlated with shear-thinning index n while proportional to the coating gap H. Combining the bubble entrainment boundary, lower n and H are favorable for a larger particulate coating window.  相似文献   
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