×Synergistic action of non-solvent induced phase separation in preparation of poly（vinyl butyral） hollow fiber membrane via thermally induced phase separation

A systematic study of air gap distance effects on the structure and properties of poly（vinyl butyral） hollow fiber membrane via thermally induced phase separation （TIPS） has been carried out. The results show that the hollow fiber membrane prepared at air gap zero has no skin layer; the pore size near the outer surface is larger than that near the inner surface; and the special pore channel-like structure near the outer surface is formed, which is quite different with the typical sponge-like structure caused by TIPS and the finger-like structure caused by non-solvent induced phase separation （NIPS）, because of the synergistic action of non-solvent induced phase separation at air gap zero. The pore size gradually decreases from outer surface layer to the intermediate layer, but increases gradually from intermediate layer to the inner surface layer. With the increase of air gap distance, the pore size near the outer surface gets smaller and a dense skin layer is formed, and the pore size gradually increases from the outer surface layer to the inner surface layer. Water permeability of the hollow fiber membrane decreases with air gap distance, the water permeability decreases sharply from 45.50× 10^-7 to 4.52× 10^-7 m^3/（m^2-s.kPa） as air gap increases from 0 to 10 mm at take-up speed of 0.236 m/s, further decreases from 4.52×10^-7 to 1.00×10 ^-8m^3/（m^2.s·kPa） as the air gap increases from 10 to 40 mm. Both the breaking strength and the elongation increase with the increase of air gap distance. The breaking strength increases from 2.25 MPa to 4.19 MPa and the elongation increases from 33.9% to 132.6% as air gap increases from 0 mm to 40 mm at take-up speed 0.236 m/s.     

Strength and elongation of spray formed Al-Si-Pb alloys

The strength and elongation to fracture of spray deposited Al-Si-Pb alloys were studied as a function of lead content, silicon content, and distance from the centre to periphery of the deposit. It is found that the ultimate tensile strength, proof stress and elongation to fracture decrease, linearly and exponentially, with the increase in lead content and porosity of the deposit, respectively. Both the strengths and elongation to fracture linearly increase with increasing distance from the centre to periphery of the deposit. The ultimate tensile strength and proof stress are higher at a higher silicon content and they have a linear relationship with the hardness of the deposit.     

Mechanical and Thermal Properties of Polysiloxanes and NBR Blend Elastomer

A series of elastomers , based on NBR , polysiloxanes （PS） were prepared and characterized by tensile tests, thermogravimetry （ TG ） and differential scanning calorimetry （ DSC ）. Two kinds of vulcanizing agent, DMDBH （2,5-dimethyl- 2,5-di （ t- butyl perory ） hexane ） and DCP （ dicumylperoxide ） were used to investigate the influence of different vulcanizing agents on properties of PS/ NBR. The addition of PS to NBR was found to improve the thermal stability and decrease the tensile strength of NBR. The tensile strength decreased conshterably while the elongation at break increased obviously with the increase of PS content. The series using DMDBH as vulcanizing agent showed a higher tensile strength and elongation at break than the series using DCP as vulcanizing agent. Simultaneity the thermal stability increased with the increase of PS content.     

Effects of Ag on microstructure and mechanical properties of 2519 aluminum alloy

The effects of Ag on the microstructure and mechanical properties of 2519 aluminum alloy were investigated by means of tensile test, micro-hardness test, transmission electron microscope and scanning electron microscope. The results show that the addition of 0.3 % （mass fraction） Ag accelerates 2519 aluminum alloy＇s age-hardening, increases its peak hardness and reduces 4 h of peak aged time at 180 ℃. The addition of 0. 3% （mass fraction） Ag increses the tensile strength at room temperature and elevated temperature. This increment at room temperature and 200 ℃ is 24 MPa and 78 MPa, respectively. In contrast, the elongation of 2519 aluminum alloy is decreased with Ag addition. The increase of tensile strength of 2519 aluminum alloy with Ag addition is attributed to the high volume fraction of Ω phase.     

Fabrication and Properties of Multilayer Chitosan Membrane Loaded with Tinidazole

With the aim of providing effective periodontal disease therapeutic method, multilayer membranes which were loaded with drug for guided tissue regeneration were prepared using an immerseprecipitation phase inversion technique. Single layer, bi-layer and tri-layer membranes were fabricated with chitosan used as cartier and tinidazole as medicine model which was loaded on the membrane. The influence of layer on structure and properties of membrane were studied by SEM, UV spectrophotometer and mechanical test. Drug release properties of three types of layer membranes were also investigated. The results showed that release rate could be slown down in both bi-layer and tri-layer membranes （to 11 days and 14 days respectively） and tri-layer membrane lasted the longest. After a process of rapid release, the concentration of tinidazole which was released by the membrane was maintained at an efficient dosage level. Compared with single layer and bi- layer membranes, we found tri-layer membrane could play a role in controlling low-rate drug release especially at the early stage of release, and keep an efficient dosage at affected part for a long period of time. The loss of drug which loaded on membrane decreased from 84.6% for single layer to 13.04% for tri-layer. The mechanical strength of three types of membrane were detected and showed that it could meet the requiremens of clinical practice. The membranes especially with tri-layer could be more valuable in application.     

Microstructures and Mechanical,Electrical,High-temperature Properties of Cu/Ti_2AlC FGM Fabricated by Hot-pressing

The microstructure and the electrical, thermal, friction, and mechanical properties of Cu/Ti_2AlC fabricated by hot-pressing at 900 ℃ for 1 h were investigated in the present work. Microstructural observations have shown that the plate-like Ti_2AlC grains distribute irregularly in the network of Cu grains, and well-structured, crack-free bonds between the layers. With the increase in the content of Ti_2AlC from layer A to layer D, the electrical resistivity increases from 1.381×10~(-7)Ω·m to 1.918 ×10~(-7)Ω·m, the hardness increases from about 980.27 MPa to about 2196.01 MPa, and the friction coefficient from above 0.20 reduces to about 0.15. Oxidation rate increases with the increases of temperature. Exfoliation was obviously observed on the surface of oxidation layer A. The surface of layer D was still intact and the spalling and other defects were not found. The mass decreases in the acid solution, and increases in the alkaline solution. The largest corrosion rate is found in 6.5% HNO_3 or 4% Na OH solution.     

Preparation and properties of composite membrane of bisphenol A-based sulfonated poly（arylene ether sulfone）and phosphotungstic acid for proton exchange membranes

A series of bi A-SPAES(Ds=0.4)/phosphotungstic acid(PWA/bi A-SPAES)composite membranes with various contents of PWA were prepared and characterized by FT-IR.Scanning electron microscopy(SEM)images indicated the PWA were well dispersed within polymer matrix.These composite membranes were evaluated for proton exchange membranes(PEM)in direct methanol fuel cell(DMFC).These membranes showed good thermal stability.It was found that the water uptake of these membranes increased with the increase of the PWA content in the hybrid membranes.Meanwhile,the introduction of inorganic particles increased both the proton conductivity and the methanol permeability.The proton conductivities of composite membranes were increased from 0.017 S/cm to 0.045 S/cm at 20 ℃ and from 0.054 S/cm to 0.093 S/cm at 100 ℃ with the increase of PWA content from 0 to 50 %.Especially,all the methanol diffusion coefficients(4.20×10-8-1.05×10-7cm2/s)of bi A-SPAES/PWA hybrid membranes are much lower than that of Nafion 117 membrane(2.1×10-6 cm2/s).Bi A-SPAES/PWA hybrid membranes were therefore proposed as candidates of material for PEM in DMFC.     

Simulation of rock deformation and mechanical characteristics using clump parallel-bond models

To properly simulate hard rock with a high ratio of the uniaxial compressive strength to tensile strength（UCS/TS） and realistic strength-failure envelope,the rock deformation and mechanical characteristics were discussed in detail when the particle simulation method with the clump parallel-bond model（CPBM） was used to conduct a series of numerical experiments at the specimen scale.Meanwhile,the effects of the loading procedure and crack density on the mechanical behavior of a specimen,which was modeled by the particle simulation method with the CPBM,were investigated.The related numerical results have demonstrated that：1） The uniaxial compressive strength（UCS）,tensile strength（TS） and elastic modulus are overestimated when the conventional loading procedure is used in the particle simulation method with the CPBM; 2） The elastic modulus,strength and UCS/TS decrease,while Poisson ratio increases with the increase of the crack density in the particle simulation method with the CPBM; 3） The particle simulation method with the CPBM can be used to reproduce a high value of UCS/TS（10）,as well as a high friction angle and reasonable cohesion strength; 4） As the confining pressure increases,both the peak strength of the simulated specimen and the number of microscopic cracks increase,but the ratio of tensile cracks number to shear cracks number decreases in the particle simulation method with the CPBM; 5） Compared with the conventional parallel-bond model,the CPBM can be used to reproduce more accurate results for simulating the rock deformation and mechanical characteristics.     

Corrosion behavior of ferritic stainless steel with 15wt% chromium for the automobile exhaust system

The effect of chloride ion concentration, pH value, and grain size on the pitting corrosion resistance of a new ferritic stainless steel with 15wt% Cr was investigated using the anodic polarization method. The semiconducting properties of passive films with different chloride ion concentrations were performed using capacitance measurement and Mott-Schottky analysis methods. The aging precipitation and intergranular corrosion behavior were evaluated at 400- 900℃. It is found that the pitting potential decreases when the grain size increases. With the increase in chloride ion concentration, the doping density and the flat-bland potential increase but the thickness of the space charge layer decreases. The pitting corrosion resistance increases rapidly with the decrease in pH value. Precipitants is identified as Nb（C,N） and NbC, rather than Cr-carbide. The intergranular corrosion is attributed to the synergistic effects of Nb（C,N） and NbC precipitates and Cr segregation adjacent to the precipitates.     

Tape casting of borosilicate glass/Al2O3 composites for LTCC substrate with various relative molecular masses of PVB

The dispersion, stabilization and rheological properties of the slurry with various relative molecular masses of PVB were studied. The sintering properties, microstructure and dielectric properties of borosilicate glass/Al2O3 composites were also investigated. The intensities of the typical vibrating bands decrease with the decrease of the relative molecular mass of PVB, which demonstrates that the content of butyral groups in PVB binders decreases correspondingly, leading to a rapid decrease in the viscosity of the mixed slurry. The solid content of samples increases with the decrease of the relative molecular mass of PVB, and this further leads to the increase of tape thickness, bulk density and dried-shrinkage coefficient of tapes. The bulk density, relative density, three-point strength and dielectric constant of sintered samples increase with the increase of the solid content, and the shrinkage and dielectric loss decrease. By contrast, samples for PVB-5s exhibit better properties of a bulk density of 3.10g/cm3 , a relative density of 98.1%, a three-point strength of 208 MPa, a ε r value of 8.01, a tanδ value of 7.6×10-4 at 10 MHz and a well matching with Ag electrodes.     

Preparation,microstructure and magnetic properties of NiZn ferrite thin films by spin spray plating

NiZn ferrite thin fihns were performed on glass substrates of 85 ℃ by spin spray plating method. X-ray diffraction patterns of the films show that the samples have a cubic spinel structure with no extra lines corresponding to any other phases between 75 ℃ and 85 ℃. As the pH value of oxidizing solution increases to 8.3, the saturation magnetization increases to 3.13 × 10^5 A/m and resistivity to 127 m Ω ·cm. Film deposited at pH 7.8 has a smooth surface and definite columnar structure. The large wavy flakes were observed at pH 8.3. The high real part of complex permeability μ′ up to 36.1 and the imaginary part μ″ up to 53.2 were observed at 0.5 GHz by short microstrip line perturbation method. The μ″ of thin film has values higher than 20 at the frequencies between 0.5 GHz and 2 GHz, the film is a promising anti-noise material for high frequency applications,     

Investigation of the Thermal Decomposition Properties of Polyoxymethylene

By testing the melt index （MI）, tensile strength and breaking extension ratio, the thermal ageing rate of polyoxymethylene （POM） was analyzed and compared. The surface morphology and type of function group of POM surface were observed and analyzed by SEM and XPS. The results show that the MI value increases gradually with the ageing time at 120℃, indicating that the thermal oxidation decomposition occurrs slowly. The effect of 20-day thermal ageing on the tensile strength and breaking extension ratio of POM is not obvious, showing that the ageing of POM is quite a long process. After 105-day, thermal ageing cracking and powdering occurr on the POM surface. XPS determination shows the Cls spectra of samples before and after ageing include two peaks of C-C and C-O, while after ageing the content of C-C decreases and the content of C-O increases, indicating that the thermal ageing of POM is mainly the breaking and decomposing of C-C bond. The Ols/Cls ratio of original samples is 56.98% and after 105-day thermal ageing the ratio is 72.92%.     

Mechanism of Surface Modification for Sericite

Surface modification of sericite by wet method was conducted with the addition of 1.0 % （w/w） silane. The resulting wetting contact angle and activity ratio of sericite were 130° and 98% respectively. Good pre-evaluation indexes of oil value （40.8%） and dispersivity （14.0 mL） were obtained. When 30 % of sericite was filled into acrylonitrile butadiene styrene（ABS） plastic, the bending strength and tensile strength of the composite material were reduced by 7% and 14.3% in comparison to those of pure ABS plastic, while the rigidity was increased by 3 times, and the impact strength and breaking elongation were reduced significantly. The mechanism of surface modification was investigated and the configuration of silane coupling agent on the surface of sericite was given. Infrared （IR） spectroscopic analysis indicates that the adsorption of silane on the surface of sericite belongs to chemical adsorption.     

Effect of annealing on composition, structure and electrical properties of Au layers grown on different thickness Cr layers

110 nm-thick Au layers were sputter-deposited on unheated glasses coated about a 10 nm-thick and a 50 nm-thick Cr layer respectively. The Au/Cr bilayer films were annealed in a vacuum of 1 mPa at 300~C for 2, 5 and 30 min, respectively. Auger electron spectroscopy, X-ray diffraction and Field emission scanning electron microscopy were used to analyze the composition and structure of the Au layers. The resistivity of the bilayer films was measured by using four-point probe technique. The adhesion of the bilayer films to the substrate was tested using tape tests. The amount of Cr atoms diffusing into the Au layer increases with increasing the annealing time, resulting in a decrease in lattice constant and an increase in resistivity of the Au layer. The content of Cr inside the Au layer grown on the thinner Cr layer is less than that grown on the thicker Cr layer. For the Au/Cr bilayer films, the lower resistivity and the good adhesion to the glass substrate can be obtained at a shorter annealing time for a thinner Cr layer.     

Thermoelectrical properties of （FeNi）xCo4-xSb12 prepared by MA-SPS

Bulk skutterudite （FeNi）xCo4-xSbl2 with x varying from 0.05 to 1.0 were prepared by mechanical alloying and spark plasma sintering （MA-SPS）. The phases of the samples were analyzed by X-ray diffraction, and their thermoelectrical properties were tested by electrical constant instrument and laser thermal constant instrument. The experimental results show that bulk （FeNi）xCo4-xSb12 have the characteristic of typical semiconductor electricity. The addition of FeNi improves the electrical properties to a large extent; the samples of bulk （FeNi）xCo4-xSbl2 （x = 0.05-1.0） are n-type semiconducting materials; the increase of FeNi content can decrease the absolute value of Seebeck coefficient and therefore decrease the ZT value; FeNi with a higher content when x 〉 0.5 leads to an evident increase in thermal conductivity and also a decrease in ZT value. In general, for ZT value, the optimal added content of FeNi is 0.25-0.5 and the maximum ZT value is 0.2467 when x = 0.5 at 500℃.     

Generation Mechanism of Interfacial Layer and Its Effect on Fe-Cr-Ni/Al-Si-Cu-Ni-Mg Composite Performance

Fe-Cr-Ni/Al-Si-Cu-Ni-Mg composite was taken as the experimental material. The chemical composition of interfacial layer was tested. The generation mechanism and influence of interfacial layer on the composite were analyzed. The results indicated that the generation of interfacial layer is sensitive to temperature. Interfacial layer will generate rapidly when temperature reaches 500 ℃ or above. The interfacial layer is mainly composed of Al, Si, Cu, Fe, and Cr, element Ni distributes at the outward of the interfacial layer for the precipitate of Ni later than Si and Cu, and there is almost no diffusion of Ni during the solution treatment. During heat treatment process, unequal quantity changing of metal atom results in disperse or concentrated vacancies or holes near the matrix. The existence of interfacial layer will induce a decrease of compression strength and plasticity at room temperature and an increase of strength at higher temperature comparing with composite without interfacial layer.     

Influence of Superplasticizers on Strength and Shrinkage Cracking of Cement Mortar under Drying Conditions

The effects of polynaphthalene series superplasticizers（PNS） with a low content of sodium sulfate （H-UNF）,with a high content of sodium sulfate（C-UNF） and polycarboxylate type superplasticizer （PC） on strength and shrinkage cracking of cement mortar under drying conditions were investigated by means of multi-channel ellipse ring shrinkage cracking test, free shrinkage and strength test. The general effect of PNS and PC is to increase the initial cracking time of mortars, and decrease the cracking sensitivity of mortars. As for decreasing the cracking sensitivity of mortars, PC〉H-UNF〉C-UNF. To incorporate superplasticizers is apparently to increase the free shrinkage of mortars when keeping the constant w/b ratio and the content of cement pastes. As for the effect of controlling the volume stability of mortars, PC〉C-UNF〉H-UNF. Maximum crack width of mortars containing PC is lower, but the development rate of maximum crack width of mortars containing H-UNF is faster in comparison with control mortars. The flexural and compressive strengths of mortars at 28-day increase with increasing superplasticizer dosages under drying conditions. PC was superior to PNS in the aspect of increasing strength.     

Pore Size Distribution of High Performance Metakaolin Concrete

The Compressive strength, porosity and pore size distribution of high performance metakaolin (MK) concrete were investigated. Concretes containing 0,5%,10% and 20% metakaolin were prepared at a water/cementitious material ratio (W/C) of 0.30.In parallel, concrete mixtures with the replacement of cement by 20% fly ash or 5 and 10% silica fume were prepared for comparison.The specimens were cured in water at 27℃ for 3 to 90 days .The results show that at the early age of curing(3 days and 7 days),metakaolin re-placements increase the compressine strength ,but silica fume replacement slightly reduces the compressine strength.At the age of and after 28 days ,the compressive strength of the concrete with metakaolin and silica fume replace-ment increases.A strong reduction in the total porosity and average pore diameter were observed in the conctete with MK 20% and 10% in the first 7 days.     

Magnetic Properties of NiCuZn Ferrite Thin Films Prepared by the Sol-gel Method

Ni0.4Cu0.2Zn0.4Fe2O4 thin films were fabricated on Si substrates by using the sol-gel method and rapid thermal annealing （RTA）, and their magnetic properties and crystalline structures were investigated. The samples calcined at and above 600 ℃ have a single-phase spinel structure and the average grain size of the sample calcined at 600 ℃ is about 20 nm. The initial permeability μi, saturation magnetization M and coercivity H of the samples increase with the increasing calcination temperature. The sample calcined at 600 ℃ exhibits an excellent soft magnetic performance, which has μi=33.97 （10 MHz）, Hc=15.62 Oe and Ms=228.877 emu/cm^3. Low-temperature annealing can enhance the magnetic properties of the samples. The work shows that using the sol-gel method in conjunction with RTA is a promising way to fabricate integrated thin-film devices.     

Effects of MgO on densification and consolidation of oxidized pellets简

The calcined magnesite was utilized as a kind of MgO bearing additive to produce MgO bearing pellets. The effects of MgO on densification and consolidation of pellets were investigated. The experimental results show that, at the same process parameters, the porosity and pore size distribution of green pellets have no evident relation with the MgO bearing additive, pore size of green pellets is between 15 μm and 35 μm and the porosity of green pellets is about 34%. There is a densification and consolidation phenomenon during the induration process; the pore size and porosity of product pellets decrease gradually; and the structure of product pellets becomes dense. MgO makes a negative effect on the densification and consolidation of product pellets, the densification ratio of pellets decreases from 46.3% to 28.6% with the addition of MgO bearing additive from 0 to 2.0 %. The porosity and the pore size of product pellets increase gradually with the increase of MgO content; When the mass fraction of MgO bearing additive increases from 0 to 2.0%, the pore size of product pellet increases and the pore size distributes in a large range. Also, the porosity increases from 18.61% to 24.06%.