Papers by Keyword: Micro-Pore

Abstract: Polyvinylidene fluoride/polyurethane (PVDF/PU) blend membranes were made via immersion precipitation process, the surface morphologies and the micro-porous structures of the blend membranes were analyzed using scanning electronic microscope (SEM) and fractal theory, the water flux change with the operation pressure of the blend membranes was investigated, and the relationship between blend membrane morphology and water flux was discussed. The results showed that, the water flux of the resulting blend membranes was increased, and the contribution of different structures to water flux was in the following order: cross-section finger-shaped porous defects > cross-section through holes > blend membrane surface pores. In addition, water flux of the blend membranes was also related to the deformability of PU.

Abstract: As a key stage in wet spinning, compacting process served as a connection between spin and post treatment, it has significant influence on the performances of polyacrylonitrile (PAN) fiber. In this paper, the influences of temperature, time and tension on the compacting process and performance of fibers were studied. The test shows that the suitable compacting process condition is 110°C for 90s with a higher shrinkage ratio. With increasing shrinkage ratio, density and breaking elongation raise, but orientation and breaking strength decrease. To obtain better effect of compacting process, loss of orientation and breaking strength can hardly be avoided; it can be compensated by secondary draw in post process.

Abstract: The tensile process of 800MPa grade dual-phase steel was observed in-situ by SEM. The initiation and propagation of crack in dual-phase steel, the initiation of micro-pores, the deformation behavior of ferrite and martensite were analyzed in this paper. The results show that the main crack goes across the soft ferrite and around the hard martensite during its propagation in the beginning. When the applied stress is small, the micro-pores are easy to form inside the ferrite grain or on the interface of ferrite and martensite. The micro-pores can also form in the fracture site of martensite with the increase of applied stress. The fracture morphology of the dual-phase steel is dimple and the formation of fracture belongs to plastic fracture.

Abstract: In this paper, several types of PVDF hollow fiber membranes used in the gas membrane separation process for extracting bromine from simulated seawater or concentrated seawater were studied. The micropore, hydrophobic property, mechanical strength and material chemistry of the PVDF membranes soaked in seawater or concentrated seawater were characterized by SEM-EDX, IR, contact angle testing instrument and electronic fabric strength tester, which were compared with those of origin membranes. At last, the mass transfer coefficient and flux during a long time were gained by operating a permeation experiment with a chosen type of PVDF membrane module.

Abstract: The effect of 1mol% calcia additive on sintering of yttria was investigated, and a yttria with elongated grains and micro-pores was developed in present work. The results showed that in calcia added samples heated at 1600°C, calcia contained yttria solid solution grains were formed and distributed among pure yttria grains. With the prolonging soaking time, they were concentrated into rod- or plate-like elongated grains and some of them were embedded into pure coarse yttria grains. Furthermore, in calcia added samples, grain growth was much faster and lots of micro-pores were left in coarse pure yttria grains. Water quench test revealed that thermal shock resistance of calcia added sample was greatly improved by elongated grains and micro-pores.

Abstract: High-strength and micropore lightweight bauxite aggregate was fabricated by low grade raw bauxite powder, aluminium hydroxide powder and organic polymer (OP). OP was used as consolidator, binder and pore former and aluminium hydroxide was used as pore former. The influence of OP and aluminium hydroxide content on the property of the samples was studied. The phase composition and the microstructure of the sintered samples were characterized by XRD, SEM and the pore size distribution was measured by mercury porosimety. The results demonstrate that the bulk density of the samples decreases linearly and the apparent porosity of the samples increases gradually with the addition of OP. The lowest density reached 1.13g/cm³ when adding 35% OP and 10% Al(OH)₃. The average pore size is around 5μm, and increases with the addition of OP increased. The XRD showed the main phase of the sample is mullite and some little amount of corundum.

Abstract: Nano-micropore latex particles (multi-hole and hollow) were applied to all kinds of sorbent, heterogeneous catalysis, carrier or other field, because of its function of adsorption and carry. Because of its cavum inside the particles, nano-micropore latex particles take on virtue of low density and great effective area, and have special character of optical and substance transmission at the same time. So make its broad application in catalyst, solar materials, photons crystal, low dielectric constant materials, sound insulation materials, message record and so on. In this paper, hydrophilic AA was chosen as polymerization monomer, and core-cell P(St-BA-AA) system were synthesized by emulsion polymerization with P(St-BA) as seed. Nano-micropore latex particles were obtained by the stepwise acid/alkali method at high temperature. The configuration of nano-micropore inside the latex particles were observed by TEM. The effects of treatment time of alkali and acid on hole forming were discussed.

Abstract: Based on micro-fluid control, a rapid metal forming method with high efficiency is proposed. At first, the basic principal is introduced. The metal liquid flows out of a large number of micro-pores, and the multipoint parallel crystallization is thus realized. During the forming process, the open or close of micro-pores is controlled by surface tension to obtain required shape of part. Then the technological parameters are deduced. Preliminary experiment shows that rapid open and close of micro-pore can be realized acted on surface tension. This method has the basic characteristics of rapid prototyping technology and continuous casting technology, which can overcome the shortcomings of inefficient and difficulty to create high melting point metal parts for current rapid prototyping.

Abstract: An analytical model is developed to study the effects of operation conditions and micro-pore geometry parameters on the friction performance of the mechanical seals with a laser-textured micro-pore face. Seal opening forces at various operation conditions and micro-pore geometry parameters are obtained from the solution of the Reynolds equation by the finite difference method. A derivative expression of the friction torque of the mechanical seals with a laser-textured micro-pore face is calculated and contributing factors of the friction torque are analyzed. It is shown that fiction torque increases with increase of the rotating speed. An optimum pore size that corresponds to minimum friction torque is found and is consistent with experimental results.

Abstract: Micropore and nanotube formation on the Ti oxide are important to improve the cell adhesion and proliferation in clinical use. In this study, nanotube and micropore of Ti alloy for biocompatibility have been investigated using FE-SEM and XRD. Ternary alloys were prepared by using high purity sponge Ti Ta, Zr and Nb sphere (99.95% wt.%). Two-step anodizing was used for surface modification of the titanium alloys. Micropore formation was first performed using a potentiostat in 1 M H3PO4 electrolyte and nanotube formation was performed in 1M H3PO4 + 0.8wt% NaF solution by using a potentiostat. The two-step anodizing process is an efficient method for forming micropores and nanotubes on the surfaces of ternary titanium alloys, and the morphology of micropore and nanotube is dependent on the alloying element and composition of ternary alloy.