In this work, the effects of support surface pore structures(including surface pore size, surface pore density and surface porosity) on the performance of thin film composite(TFC) gas separation membrane over a wide pressure range(from 0.3 to 2.0 MPa) were studied. To fulfill it, the polysulfone(PSf) supports with different surface pore structures were prepared. Two kinds of wide-accepted polymeric membrane materials, i.e., polyvinylamine(PVAm) and Pebax 1657 copolymer, were used as skin layer materials. We pointed out for the first time that the support surface average pore size and pore density could affect the chain mobility of polymer of skin layer at the support surface pore entrance, then, can affect the TFC membrane performance. Besides, we also discussed the effects of support on the TFC membrane performance when the feed pressure changes for the first time. This work can provide guidance for choosing a suitable support for TFC gas separation membrane. 相似文献
Neural Computing and Applications - Much recently, based on the discrete-time nonlinear output regulation (NOR) theory, a neural network (NN) method combined with feedforward friction compensation... 相似文献
In the present work, Tungsten (W)/oxide dispersion strengthened (ODS) steel joints were fabricated by the direct solid state diffusion bonding (SSDB) technology with a multistage cooling process, and the microstructure and tensile strength of the bonded interfaces and parent materials were experimentally investigated. The results show that W and ODS steel can be successfully bonded at the temperature ranging from 900 °C to 1050 °C, without severe macroscopic deformation or obvious microscopic defects. Reaction layers generated at the bonded interfaces are evolutive with the bonding temperature, result in different fracture locations of the bonded joints. In the joint bonded at 950 °C, a higher interfacial strength of ~ 234.2 MPa is achieved, due to the formation of nano-scale intermetallic compound FeW. Microstructure of W remains stable after all the SSDB processes, while the lath structure of ODS steel is completely broken and transformed into the equiaxed grains, which should be responsible for the deterioration of strength. When the bonding temperature is higher than 950 °C, the pinning effect of precipitates M23C6 and nano-oxide particles on the movement of dislocations is observed.
Recently, the curly structure attracts researchers' attention due to the strain effect, electronic effect, and improved surface area, which exhibits enhanced electrocatalytic activity. However, the synthesis of metastable curved structures is very difficult. Herein, a simple room temperature coprecipitation method is proposed to synthesize 3D cobalt (Co) hydroxide (α‐Co(OH)2) electrocatalysts that consist of curly 2D nanosheets. The formation process of curly nanosheets is elaborated systematically and the results demonstrate that the ? NHx group has great effect on the formation of curly structure. Combining the advantage of 2D curly nanosheet and 3D aggregate structure, the as‐prepared α‐Co(OH)2 curly nanosheet aggregates show the best water oxidation activity with an overpotential of 269 mV at j = 10 mA cm?2 in 1.0 m KOH. The electrocatalytic process studies demonstrate that the formation of CoIV?O species is the rate‐determining step. Theoretical calculations further confirm the beneficial effect of the bent structure on the conductivity, the adsorption of OH? and the formation of OOH* species. 相似文献
The hot deformation behaviors of Ni18Cr9Co9Fe5Nb3Mo superalloy were explored in the formation temperature range free ofγ'phase with various strain rates applied.The hot deformation behaviors are initially modeled with Arrhenius equation which gives an average activation energy of 581.1 kJ mol-1.A modified Arrhenius approach,including the updated Zener-Hollomon parameter is proposed to consider the change of activation energy under different deformation conditions which turns out a relatively accurate computation for activation energy of hot deformation,i.e.,the standard variance for modified model calculated in the covered deformation condition is just 35.4 % of that for Arrhenius equation.The modified model also proposes a map for activation energy which ranges from 571.5-589.0 kJ mol-1 for various deformation conditions.Microstructural features of the representative superalloy specimens were characterized by electron backscattered diffraction (EBSD) techniques in order to clarify the influence of activation energy on the microstructural formation.It is found that the Ni-based superalloy samples with higher activation energy are promoted by the degree of dynamic recrystallization which suggests that the rise in activation energy gives either a better recrystallization rate or finer grains. 相似文献
The assembly design of nanostructures has taken a dominated position in improving gas sensing properties. In our work, multi-hierarchical (nanoneedles assembled and nanosheets assembled) SnO2 nanostructures with size-controllable blocking units were synthesized via facile hydrothermal method. As is recorded, the addition of PVP led to the transformation from nanoneedles assembled nanostructures into nanosheets assembled nanostructures, which can be ascribed to linear molecule structures. While the sizes of the blocking units can be controlled by the temperature due to the Ostwald ripening. And seeing from the gas sensing measurement, the thinner ones had higher gas response and quicker gas response and recovery judging from the sizes of blocking units, at the same time, nanoneedles assembled hierarchical structures possessed higher gas response while nanosheets assembled hierarchical structures had shorter gas response and recovery time. 相似文献