Design and optimization of ceramic membrane structure: From the perspective of flux matching between support and membrane

The support flux was first investigated as a separate influencing factor for its effect on performances of ceramic filtration membranes. Three pre-membranes were prepared by tape-casting and then transfer-coated to supports to form dual-layer ceramic membranes after sintering. Experiments demonstrated that membrane layers with almost the same properties were obtained despite the huge difference in support flux. When the support flux increases from 3.120 to 97.53 m³m^?2h^?1, the flux of these three membrane series have increased by 75%, 186% and 228%, respectively. Experimental rules can provide structural design and evaluation from the perspective of permeability. The limit membrane flux of a certain system was derived according to the resistance distribution law of internal membrane structure and the Darcy's theorem. On this basis, a method for designing support flux was proposed. Furthermore, we present a criterion to quickly and easily evaluate the match between the support and the top layer, which is the ratio of membrane resistance to total resistance. Finally, the filtration resistance of penetration caused by suction of membrane particles into the support was measured for the first time, taking the advantage of the transfer-coating method that inherently free of penetration. Our works are expected to deepen the understanding of the ceramic membrane structure and provided guidance for its rational design and optimization.     

臭氧技术在废水处理中的应用

由于臭氧的强的氧化性能,使其成为一种强氧化剂和消毒剂;臭氧技术已经广泛用于废水处理行业,臭氧具有较好的的消毒杀菌、脱色、除臭味等作用,文章通过介绍臭氧的一些基本性质,臭氧消毒杀菌、氧化、脱色及除臭味的机理,臭氧的制取方式,现代臭氧技术的研究方向等,为废水处理中臭氧技术的应用提供参考。     

一种柔性踝关节助力机构研究

为解决传统的刚性外骨骼助力机构限制人体关节运动的自由度和大幅增加人机惯量的问题,设计了一种柔性踝关节助力机构,并提出了一种根据足底压力传感器估计踝关节力矩大小和变化趋势的算法。最后,通过实验证明了这种踝关节助力机构的可行性和有效性。     

改性Kevlar纳米纤维对天然橡胶耐溶剂性能和交联密度的影响（英文）

制备了改性Kevlar纳米纤维(m-KNFs)填充天然橡胶硫化胶,研究了不同用量的m-KNFs对天然橡胶耐溶剂性能和交联密度的影响。结果表明,m-KNFs可有效增强天然橡胶的耐溶剂性能,当m-KNFs的用量为7份时,天然橡胶的溶剂吸附常数比未填充时降低了11. 7%。同时,天然橡胶的交联密度随着m-KNFs用量的增加而增大。     

Research on hydrophobicity of electrospun Fe3O4/PVDF nanofiber membranes under different preparation conditions

Abstract

Preparation condition can affect the structure and the properties of nanofiber membrane. In order to explore suitable conditions to prepare the Fe₃O₄/PVDF nanofiber membrane with good hydrophobicity, the hydrophobicity of Fe₃O₄/PVDF nanofiber membranes obtained by electrospinning was investigated by changing preparation conditions like weight percentage of Fe₃O₄ nanoparticles, blending quality concentration of poly (vinylidene fluoride) (PVDF) and Fe₃O₄ nanoparticles, and positive voltage. And the variations of hydrophobicity of Fe₃O₄/PVDF nanofiber membranes modified by 1H, 1H, 2H, 2H-perfluorodecyl trimethoxysilane were studied. The results show that the hydrophobicity of Fe₃O₄/PVDF nanofiber membranes has changed under different preparation conditions. The contact angles of samples increased after a modification by 1H, 1H, 2H, 2H-perfluorodecyl trimethoxysilane, which indicates that the hydrophobicity of Fe₃O₄/PVDF nanofiber membranes has been enhanced.     

焙烧铁尾矿制备透水砖试验研究

为了改善尾矿制砖的力学性质，解决尾矿堆积问题，采用焙烧铁尾矿、水泥和粉煤灰为胶凝材料，2.36~4.75 mm粒级铁尾矿为粗骨料，通过搅拌、成型和养护工艺制备透水砖，探究了焙烧铁尾矿用量、水胶比、目标孔隙率和振动时间对透水砖性能的影响，对比未焙烧尾矿制备透水砖的性能。结果表明：① 焙烧尾矿制备透水砖最佳试验条件为：焙烧尾矿掺量60%，振动时间40 s、水胶比0.3，目标孔隙率20%；此时，透水砖抗折强度为3.34 MPa，符合国家标准Rf3.0，抗压强度为15.44 MPa，符合国家标准MU15，透水系数为2.58×10-2 cm/s，符合国家标准A级标准，实测孔隙率为23.41%。② 焙烧尾矿掺量为60%时效果最佳；未焙烧尾矿掺量为50%时效果最佳，抗折、抗压强度分别为3.38 MPa和14.54 MPa，透水系数符合国家A级标准；焙烧尾矿比未焙烧尾矿多替代水泥10%的情况下，力学性能焙烧尾矿透水砖较好，而透水性能则未焙烧尾矿透水砖较好。     

木质素基表面活性剂研究现状

木质素作为一种天然高分子化合物，其来源丰富，可以用来代替石油资源制备表面活性剂，缓解当前石油资源枯竭的问题。常见的木质素基表面活性剂有阳离子表面活性剂、阴离子表面活性剂、两性离子表面活性剂以及非离子表面活性剂。木质素基表面活性剂在工业领域具有广泛的应用范围，可以作为染料分散剂、混凝土减水剂、沥青乳化剂以及原油采集过程中的驱油剂等。木质素基表面活性剂的开发利用为生物质产品的高值化利用开辟了一条新的路径。     

工艺参数对超声辅助脉冲电沉积镍-氮化钛复合镀层的影响

在45钢表面以超声波辅助脉冲电沉积制备Ni-TiN复合镀层。研究了平均阴极电流密度、脉冲占空比、超声功率和TiN粒子(平均直径20~30 nm)添加量对复合镀层的TiN粒子含量和显微硬度的影响。得到较优的工艺参数为:NiSO4ꞏ6H2O 300 g/L,NiCl2ꞏ6H2O 30 g/L,H3BO330 g/L,十二烷基硫酸钠0.3 g/L,TiN 25 g/L,pH 4.1~4.3,温度40°C,平均阴极电流密度4 A/dm2,脉冲占空比40%,脉冲频率1000 Hz,超声功率300 W,机械搅拌速率200 r/min,时间60 min。该条件下所得Ni-TiN复合镀层的TiN质量分数为8.35%,显微硬度为819 HV,表面平整、致密,晶粒尺寸均匀。     

强变形工艺对2519A铝合金组织与性能的影响

通过硬度测试、拉伸性能测试、透射电镜观察等分析手段研究了不同强变形工艺下2519A铝合金的力学性能与微观组织。结果表明,经50%的冷轧变形和165 ℃人工时效后,2519A合金的力学性能明显提高,其抗拉强度、屈服强度和伸长率分别为522 MPa、468 MPa和8.5%。而在冷变形前添加165 ℃×2 h预时效处理,合金的力学性能进一步提高,其抗拉强度、屈服强度和伸长率分别达到535 MPa、497 MPa和8%。预时效处理可以提高合金中θ′相的密度,使析出相分布更加均匀,有助于提高合金的力学性能。     

基于热电效应的高效环控系统

部分空间科学实验对环境温度有较高的要求，环境温度高于或低于空间科学系统能够提供的热沉温度，需要有可靠有效的加温降温处理措施。使用可靠性强的热电制冷片作为制冷制热方式和气液换热器二次换热来实现环境温度控制的需求，并对不同流体温度制冷制热效果进行分析，结果表明流体温度和目标温度差越小，热电制冷制热的效果越好。在环境温度制冷工况中，热电单元数量随电流增加先减少后增加，在制热工况中则单调递减，设计中需按照制冷工况进行热电单元数量的确定。当流体温度接近制冷制热的目标温度时，会出现整个系统总效率优于热电系统效率的区间。通过对热电单元和气液换热器的组合系统的性能计算，提供一种适于热电环控系统的计算方法和部件选型思路，对空间站环控系统的设计有重要参考意义。