仿生超疏油材料在苛刻工况条件下的应用

超双疏兼备超疏水和超疏油两种极端不润湿现象,其中超疏油的实现难度更大,应用前景广阔。为了获得超疏油材料,通常采用仿生思路,在材料表面构建粗糙结构和以含氟低表面能物质修饰表面。表面粗糙结构在机械力学作用下易遭到破坏,例如摩擦和冲击。低表面能物质修饰层在光照条件下易分解,而诸多的太阳能装置如太阳能电池板,必须在室外工作。耐紫外的超疏油性可以帮助这些设施实现高效工作并延长使用期限,节约资源。更进一步,科研人员研究了超疏油材料在各种苛刻条件下的可靠性。本文应用新进展聚焦在超疏油材料在紫外线照射下的可靠性或可逆响应性;超疏油材料经过撞击之后的油滴接触角变化;在高温条件下超疏油材料的极端润湿性能保持能力;在冲击条件下的稳定性,甚至包括了多种复合苛刻条件下的超疏油材料的耐受性。由于大多的工业环境无法避开摩擦和腐蚀,因此本文着重从超疏油材料的耐摩擦性和抗腐蚀性两个方面讨论了其研究现状,同时也讨论了超疏油在其他工程应用方面的可靠性。最后,总结了各实验方案的优缺点、实验与工业化过程中存在的问题、有望突破的方向,以及作者对于在苛刻工况条件下提升超疏油材料可靠性的观点。     

氮掺杂石墨炭包覆的钴纳米催化剂作高效、高稳定性电催化制氢

电催化制氢是解决当前能源危机的重要手段之一。 研究高效稳定的非贵金属电催化剂是电催化制氢商业应用的重点。 本文通过直接高温热解双金属沸石咪唑骨架,制备了一种氮掺杂石墨炭(NC)包覆均匀分布的钴纳米颗粒电催化剂(V-Co@NC,这里V是vacancy缩写),前躯体中的Zn元素有效地防止钴纳米颗粒的聚集,并有助于生成均匀分布的钴纳米颗粒。 这种特殊的纳米结构可防止钴与电解液的直接接触,提升了其循环稳定性,同时,氮元素的掺杂提升了导电性,有利于电催化制氢性能的提升。 结果表明,所制备的V-Co@NC催化剂在酸性和碱性电解液中均具有良好的催化性能,且经过5000次循环测试后催化活性基本保持不变,具有良好的应用前景。为高活性和高选择性的电催化制氢催化剂的发展提供一种全新的途径。     

质子交换膜燃料电池膜电极耐久性的提升

质子交换膜燃料电池由于具有能量转换效率高、操作温度低、环境友好等优点而备受人们关注。随着2014年丰田发布燃料电池电动汽车Mirai,带来了新一轮燃料电池及燃料电池汽车的产业化热潮。然而,提升质子交换膜燃料电池的寿命,开发新一代长寿命燃料电池膜电极及燃料电池仍然是本领域的挑战性课题。膜电极(MEA)是质子交换膜燃料电池最核心的部件,其耐久性直接决定着燃料电池的寿命。MEA主要由质子交换膜、催化剂层、气体扩散层三部分组成。本文从质子交换膜、催化剂及载体、气体扩散层三个方面介绍了近年来国内外在提升燃料电池膜电极的寿命(耐久性)方面所做的工作,并对未来的相关研究和发展做了述评及展望。     

Effect of Interruptions in Loading on the Durability and Deformability of Structural Plastics

An alternative way of estimating the durability of structural plastics under stresses = const 0.4-0.8_f(_f is the failure stress) based on test data obtained in multiple rectangular loading-rest cycles is proposed. It is also suggested to employ the decrease in the instantaneous elastic modulus as a criterion for evaluating the residual service life of plastic parts and structures and elucidating the reasons for their early failure. For the first time, a possibility of considerably increasing the durability and endurance of structural plastics under short pulsed loadings with relatively long interruptions at the initial stage of stress concentration is considered. The cases of a significantly increased endurance of plastics caused by long interruptions after some fatigue loading by high-frequency tension cycles with a zero maximum stress are explained. First experimental confirmations of an increased durability and endurance of microcomposites subjected to short pulsed loadings alternating with long interruptions are obtained. The evolution of the effect of the loading-rest modes on the durability of massive specimens, microcomposites, and dry fibrous reinforcing fillers is demonstrated with examples of a glass-fabric laminate, a microcomposite, and a nonimpregnated glass strand.     

湿热环境下FRP加固RC构件耐久性实验方法研究

现有的耐久性实验方法没有体现环境与载荷的耦合作用,这与桥梁结构等主要承载构件的服役条件差异较大,会导致实验结果与实际构件的耐久性有较大的出入。为了能较真实地模拟桥梁的主要承载构件的服役状况,本文以在亚热带湿热环境下服役的钢筋混凝土(RC)桥梁为对象,探讨温度和湿度的周期变化规律、以及桥梁的活载(车辆载荷)的统计特性。初步提出了服役环境与载荷耦合作用的仿真及实验方法,构筑和集成了实验系统,为湿热环境与车辆荷载(随机载荷)耦合作用下构件的耐久性研究提供了初步的实验方法和平台。     

碳纤维及浸润树脂自然老化性能的模型预测

对目前土木工程加固常用的两种碳纤维片材及树脂耐久性进行了对比性试验研究.截至自然老化3年时,已进行了16组共80个试件的试验.考察在我国自然环境条件下抗拉强度的老化.根据复合材料的中值老化剩余强度半经验数学模型,对其进行拟合,回归出CFRP复合材料及其树脂的剩余强度中值方程的相关参数.预测复合材料自然老化剩余强度.对复合材料进行寿命预估,供进一步研究和工程设计参考使用.     

Scratch resistance and weatherfastness of uv-curable clearcoats

UV-cuing has found an increasing number of industry allocations over the past decade due to its unique benefits, e.g. solvent free formulations, high cure speed and low temperature processing. In addition to these benefits two additional properties of uv-cured coatings are of today's interest, especially in the automotive industry: scratch resistance and resistance against chemicals. One of the most important requirements for a broad use of uv-curable coatings in the coating industry is that coatings are stable against degradation caused by atmospheric influences since coatings for outdoor use are subject to especially harsh weathering conditions, e.g. uv-light, oxygen, moisture and air pollutants. This weathering leads to a degradation of the polymeric binder. Clearcoats containing photoinitiators based on bis-acylphosphinoxide (“BAPO”) and a combination of hydroxyphenyl-s-triazine uv-absorber and a sterically hindered amine as a light stabilizer package show a very good curing behavior as well as an improved weatherfastness over a long period of time and a good scratch and chemical resistance.     

Evaluating Properties of Green Concrete Produced Using Waste Marble Powder,Quarry Dust,and Paper Pulp

Industrial waste locks are used as raw materials to reduce harmful effects on the environment and improve environmental performance. Marble clay powder can be used as a filling aid and can fill voids in concrete structures. This article will show you how to use a maximum natural sand alternative in concrete with marble powder and quarry dust. The challenge of the 21st century is to change to a new form that can support the natural system. This necessitates a radical rethinking of how to give the community infrastructure and housing. Making a concerted effort to develop novel, innovative, and alternative construction materials may be necessary. Jungles of concrete around cause's impact on the Environment and it would result in climate change. Mankind must avoid the use of things that are detrimental to the environment. So in this paper, it is decided to address the issue by adopting the use of the green concrete concept which is environmentally friendly. Green concrete is concrete made up using industrial wastes such as marble powder, quarry dust, wood ash, paper pulp, etc. Green concrete, which is capable of sustainable development, helps to reduce the consumption of natural resources, energy use, and environmental pollution. Green concrete is more cost-effective than ordinary concrete and reduces the cost of resultant concrete by 14%–20%. It is also observed that the alkali-aggregate reaction and sulfate attack resistance of concrete are both significantly improved. Green concrete is a useful tool for lowering environmental pollution and enhancing concrete's resistance to harsh conditions. All stages of infrastructure construction and rehabilitation will follow this trend of using new cement and techniques. Green concrete's adaptability and its performance derivatives will meet a variety of future needs.     

Accelerated Characterization of Electrode-Electrolyte Equilibration

Operational durability is poorly characterized by traditional (photo)electrocatalyst discovery workflows, creating a barrier to scale-up and deployment. Corrosion is a prominent degradation mechanism whose thermodynamics depend on the concentration of corrosion products in electrolyte. We present an automated system for characterizing the equilibration of (photo)electrodes with dissolved metals in electrolyte for a given electrode, pH, and electrochemical potential. Automation of electrode selection, electrolyte preparation, and electrolyte aliquoting enables rapid identification of self-passivating electrodes and estimation of the equilibrium dissolved metals concentrations. The technique is demonstrated for metal oxide photoanodes in alkaline electrolyte, where BiVO₄ is found to continually corrode, in agreement the literature. An amorphous Ni−Sb−O photoanode is found to passivate with a Ni-rich coating on the order of 1 monolayer with less than 1 μM total dissolved metals in electrolyte, demonstrating its suitability for durable photoelectrochemical operation. The automation and throughput of the instrument are designed for incorporation in accelerated electrocatalyst discovery workflows so that durability can be considered on equal footing with activity.