A new–type environment friendly sand-fixing agent of sodium carboxymethyl cellulose (CMC) grafted onto acrylamide was synthetized and characterized. The effects of the ratio of CMC to acrylamide, initiator concentration, reaction time, initial temperature and starting pH on the sanding-fixing properties were investigated. The results showed that as the ratio of CMC to acrylamide increased, the thickness of solidified layer and water retention increased gradually and the strength and water resistance first increased and then decreased. And when the ratio was 2:1, the strength and water resistance were the best and the thickness and water retention of the solidified layer reached balance; as the concentration of initiator increased, the thickness of the solidified layer, strength and water resistance first increased and then decreased, water retention increased gradually, and when the concentration of initiator was 0.15 g/L, the thickness, strength and water resistance of the solidified layer were the best, and water retention reached equilibrium. The cellulose long–chain of CMC makes the sand-fixing agent with good adhesive and film–forming property; the hydrogen bonding of the strong hydrophilic amino in acrylamide makes the sand–fixing agent with excellent water retention and hydroscopicity; the complexation of the carbonyl on chain and the inorganic ions on sandy soil could increase the adhesive and film–forming
properties.

The effects of deforming texture and deformation mechanisms of slip and twinning on the comprehensive performance of AZ31 magnesium alloy sheets were investigated by using uniaxial tensile test with controlled strain rate. The results show that the Schmid factor of {0002} basal plane is low, the slip of basal plane is difficult to start, and the yield strength is bigger along the tensile direction of extrusion. The grains of prismatic orientation lie in the best position for {0002} plane slipping, and the prismatic slip of the basal plane orientation also is in the best position. Therefore, the yield strength is low, and the elongation is bigger along the tensile direction of 45^o. The twins have an important effect on the mechanical properties of the sheets, and the elongation is lower because the large numbers of twins induce crack along the transverse tensile direction. The large numbers of tensile twins are the inducement of producing the double peak texture of {0002} palne along the tensile direction of 45^o and transverse direction.

Superdrophobic surfaces on MB8 magnesium alloy substrate were prepared by regular surface texture by laser manufacturing and perfluorodecyltrichlorosilane (FDTS) self–assembled monolayers deposited on texturing surface. The surface properties and the contact angle of specimen were analysed. The results show that the contact angles of the water droplet on the substrates increase significantly (maximum value 150^o) after laser manufacturing and self–assembled monolayers preparation. Rough structure of substrate by laser manufacturing and low surface energy material FDTS self–assembled monolayers are the main factors for preparing superhydrophobic surface. The carrying capacity of platforms maded of superhydrophobic substrate increases with contact angle increasing, and is greater than that of non–superhydrophobic platforms significantly. The calculation results and the existence of “air cushion” are in accord with the Cassie–Baxter model’ state. Comparation of the contact angle between the measurement and theoretical value indicates that hierarchical structure plays an important role in preparation of superhydrophobic surface.

The hybrid membrane was prepared through reversed phase cast method by blending the anatase-TiO2 nanoparticles with the PVDF casting solutions. The metallographic microscope, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to character the hybrid films, and the effects of TiO2 nanoparticle content on the properties of the TiO2/PVDF hybrid membraine were investigated. The results showed that a promoted adsorption and elution efficiencies of PVDF/TiO2 hybrid membranes were observed compared with that of the neat PVDF film. And with increase of TiO2 nanoparticle content, the surface water contact angle of the hybrid membraine decreases, the hydrophily, pure water flux (TiO2 nanoparticle content <8%) and the contamination resistance increase. The optimum conditions were determined as follows: w(LiCl)=2%, w(PEG600)=2%, w(PVDF)=20% and w(TiO2)=5%–8%.

Pt nanoparticles were prepared on Al2O3 films by atomic layer deposition using (MeCp)Pt(CH3)3 and O2 as precursors, and the effect of rapid thermal annealing (RTA) on the characteristics of Pt nanoparticles was investigated. The results show that as the annealing temperature rises from 700 to 900℃, Pt nanoparticles exhibit the increase of the dimensions and self-separation, a tendency to spherical growth, and a slight decrease in particle density. With increasing the annealing time from 15 s to 60 s at 800 !, Pt nanoparticles grow big gradually together with increscent dimension dispersion and a decreasing density. Therefore, it is concluded that the annealing at 800℃ for 15 s can achieve high density (9.29×10¹¹cm⁻²), uniform and well–separated Pt nanoparticles. Moreover, when the annealing temperature is increased to 900℃, some Pt atoms are oxidized, which is likely due to the interfacial reaction between Pt and Al2O3.

Translucent, crack–free monolithic alumina aerogels were prepared at room temperature by sol–gel method combined with the ethanol supercritical drying technique using alumina tri–sec butoxide and nitric acid as the precursor and catalyzer respectively. Hydrolysis and condensation were controlled  in different steps. The density of the derived aerogel is 120 kg/m3. The micro–structure and thermal properties of the alumina aerogels were analyzed by SEM, XRD, FT–IR, thermal analyser (Hotdisk) and pore size distribution analyser. The heat transfer mechanism was explained from different aspects of aerogels’ micro–structure. The results show that the alumina aerogels prepared by this method are materials with obvious polycrystalline of boehmite phase and nano–sized multi–hole network structure with spherical particles, which grately reduced the gas and solid thermal conductivity. The total thermal conductivity of the aerogels obtained is 0.020 W/m·K at room temperature.

The effects of electromagnetic stirring frequency on solidification structure and macro composition segregation of Pb–80%Sn hypereutectic alloy cast ingot were investigated and compared with that without magnetic field. The results show that the spiral magnetic field can make the distribution of solute and temperature field more uniform than that of rotating magnetic field for the formation of larger zone stirring in the ingot. For a fixed excitation current, the grains size of primary phase decreases with the increasing of frequency, and an optimal effect can be obtained when the frequency reaches 13 Hz for rotating magnetic field and 10 Hz for spiral magnetic field. The grains sizes can reduce to 142.5 μm and 140.6 μm from 247.3 μm in the absence of magnetic field respectively. However, the solidification structure will coarsen and non-homogenize as the frequency increases. The composition segregation can be the minimum when the frequency is 13 Hz for both rotating and spiral magnetic field, which are reduced from 9.71% under no magnetic field to 1.14% and 0.34% severally.

The changes of surface layer mechanical properties for duplex stainless steel and austenitic stainless steel after cavitaion corrosion were investigated by nano-indentation, and the relationship of surface layer mechanical properties with cumulative mass loss and microscopic corrosion morphologies was further investigated by weight loss and SEM. The results show that there are obvious effects of the microstructures on the changes of surface layer mechanical properties with displacement. Although stainless steels with different microstructures have different corrosion morphologies after cavitation corrosion, there is a same threshold for the degradation of surface layer mechanical properties, below which stainless steels were heavily subjected to cavitation corrosion and the microscopic morphologies of their corroded surfaces change markedly. This threshold is not related with the microstructures of stainless steels.

The rationship between surface pre-oxidation and low-temperature sintering of uranium dioxide powders was studied in this paper. The oxidation processess of uranium dioxide powders in air were analyied by DSC-TG.Morphology, phases and properties of modified powders were tested by SEM, XRD and BET. Sintering properties of uranium dioxide powders before and after modification were compared and researched by thermal expansion instrument. The Results show that a process of 240℃×8h in air is a better process to surface modify uranium dioxide powders in our conditions. Beginning shrinkage temperature of modified powser pellets in Ar decresed from 1096-1171℃to 572-576℃, average line shrinking rate increased from 151.5266×10-6/K to 308.2275×10-6/K, density of the uranium dioxide pellets increased also from 8.52g/cm3 to 9.44g/cm3. Obviously, sintering densitying of modified powders is more rapid and higher than before. Density of the modified powders sintered pellets at 1300℃×5h/N2+5%CO2-1500℃×1h/H2 is 10.26 g/cm3。

Rotary bending gigacycle fatigue properties of Al–7Si–0.3Mg alloys were investigated, and the S–N curve and critical stress 88 MPa under fatigue life of 107 cycs were obtained. The results of fracture analysis show that the fatigue fracture mainly occurred at surface flaws or defects in the region of high stress amplitude level, whereas the fatigue fracture mainly occurred at a subsurface porosity in the region of low stress amplitude level. The quantitive relationship between porosity diameter and fatigue life was established and the critical size of porosity on different stress was obtained by using the formula Paris.

The nano–sized mesoporous MCM–41–M, chemical modification of MCM–41–M by coupling agents, and four different coupling agents were used to prepare natural rubber(NR) composites. The effects of content of nano–sized mesoporous MCM–41–M, the kinds of coupling agents, and adding method of coupling agent on the mechanical properties of the composites were investigated. The results show that the MCM–41–M has better reinforcing effects in the NR matrix. The tensile strength of the NR composites raised by 12.7% compared with pure NR when the content(mass fraction) of MCM–41–M is 3%. Compared with NR/MCM–41–M/KH–570, the tensile strength of NR/KH–570 modified MCM–41–M raised by 50%. NR/KH–570 modified MCM–41–M shows a higher glass transition  temperature, lower tanδ peak value and higher storage modulus under all temperature regions.

A high–strength concrete material was prepared by using fly ash and iron ore tailings as major raw materials. Reaction products and microstructure of hydrated harden samples of the high–strength concrete material were analyzed by XRD and SEM methods, and the influences of several factors, such as proportion of iron ore tailing, water–binder ratio and dosage of super plasticizer, on the mechanical properties of the high–strength concrete material were investigated. The results show that the prepared concrete material is composed of large ratio of solid waste up to 86.4% (mass fraction), and its compressive strength reached to 100.1 MPa with a flexural strength of 20.6 MPa. The early strength of the samples was developed by the formation of large amount of C–S–H gel and ettringite during the early hydration stage. The continued development of strength in the last stage was mainly caused by pozzolanic reactions of the waste materials which leaded consumption, reduction and disappearance of Ca(OH)₂ in the system.

Different low-dimension carbon nanostructures, such as onion-like carbon, bamboolike carbon and carbon nanotubes, were prepared via in-situ catalytic pyrolysis of phenolic resin with Ni(NO3)2·6H2O as catalytic precursor, and characterized by X-ray diffraction, field-emission scanning electron microscope and transmission electron microscopy. The results show that carbon nanotubes with a narrow diameter distribution are more easily formed in a compact mass by a well dispersed Ni catalyst when the molar ratio of Ni(NO3)2·6H2O to phenol is under 0.01. When the ratio of Ni(NO3)2·6H2O to phenol is 0.04 above, Ni catalyst were prone to be aggregated, leading to a widened diameter distribution and sparse growth of carbon nanotube. When the ratio reached to 0.10, a more serious catalytic aggregation was observed and no carbon nanotube was prepared. The possible mechanisms were proposed for the formation of onion-like carbon, bamboo-like carbon and the carbon nanotube.

The uniaxial hot compression test with Gleeble–1500D thermal simulator had performed on Mg–9Li–3Al–2.5Sr alloy at 200–350℃ and strain rates of 0.001–1 s⁻¹. The correlation between the flow stress and the temperature and strain rates were analyzed, the constitutive equation of the alloy at elevated temperature was established, and the hot processing map of the alloy was also calculated and investigated by observing the microstructure. The results show that the flow stress becomes higher with increase of strain rates at constant temperature, and lower with increase of deformation temperature at constant strain rate. The steady flow stress of the alloy deformed at elevated temperature can be well described by the hyperbolic sine constitutive equation. The result of hot processing map shows that the optimal hot working parameters for the alloy Mg–9Li–3Al–2.5Sr is at 260–300℃ and strain of 0.01–1 s⁻¹, and the super–plastic deformation domain is at 340–350℃ and strain of 0.003–0.01 s⁻¹.

The effect of copper addition on the strength and cryogenic toughness of 9Ni steel was investigated and the mechanism of strengthening and toughening of Cu-bearing 9Ni steel was discussed in connection with the microstructure characteristics. The results show that the room-temperature yield strength and ultimate tensile strength of the 9Ni steels heat-treated by quenching + lamellarizing + tempering (QLT) process increase by about 150 and 105 MPa respectively when the copper content was increased from 0% to 1.5%. And the impact energy at −196   increased as Cu content increases within 1% but decreased beyond 1%. At the same time, highest impact energy reaches to 157 J for Cu content of 1.0% though the steels with other Cu contents also have high level impact energy. The microstructure observation result reveals that, with increasing Cu, the strength increased due to increasing secondary tempered martensite and Cu particles precipitated finely. On the other hand, Cu addition increases the volume fraction of reversed austenite and improves the stability of formed reversed austenite resulting in cryogenic toughness improvement.

The IMC layer microstructure and the composition of In3Ag solder joint were observed and analyzed using SEM and EDS, and the shear strength of solder joint was measured using mechanical testing machine. The effects of reflow soldering cycles on microstructure and shear property of In3Ag solder were investigated. The results show that with increase of the reflow soldering cycles, the quadratic phase AgIn2 in solder matrix grows prominently, and the shape changes from grain to long strip. The thickness of (Ag, Cu)In2 layer increases linearly, which is controlled by interfacial reaction rate and component diffusion rate. The shear strength of solder joints decreases with reflow soldering cycles increasing, and those decrease from 5.03MPa after one cycle to 2.58MPa after five cycles. The fracture type is ductile fracture in solder matrix after 1, 2 and 3 cycles. After five reflow soldering cycles, the fracture type belongs to the mixed fracture of toughness and brittleness.

The thin film of ITO/PEDOT : PSS/PCPDTBT : PC61BM were fabricated and the effects of film-forming additives on the photoelectric properties of PCPDTBT : PC61BM were investigated. The results show that the film-forming additives results to a red shift of the absorption peak of PCPDTBTPC61BM active layer, substantially improvement of the performance of the solar cell. The existence of film-forming additives can lead to a nanoscale phase separation and increase of the contact interface between the donor and acceptor. The efficiency of photoinduced exciton separation, the carrier mobility and electrode collection charge carrier efficiency can be increased, thereby the device performances can be significantly improved by film-forming additives. Open circuit voltage of 0.66 V, short circuit current density of 10.42 mA·cm⁻², fill factor of 0.38 and power conversion efficiency (PCE) of 2.64% were achieved under the condition of 100 mW·cm⁻² air-mass 1.5 solar simulator illumination.

Ampholytic polyphenylene sulfide (P–SO3–TMA and P–SO3–DMA) was prepared from sulfonated polyphenylene sulfide (P–SO3) by bromination, followed by the substitution of bromine by quaternary ammonium group and tertiary amine group. The properties of ampholytic polyphenylene sulfide, such as dissolubility, reduced viscosity, intrinsic viscosity, rheological behavior and thermostability, were investigated, and the effects of key factors on performance were studied. The results showed that polar groups on the chain of sulphonated PPS through bromination and the substitution of bromine by quaternary ammonium group and tertiary amine group, make ampholytic PPS soluble in polarity solvent. The viscosities of P–SO3–TMA and P–SO3–DMA have a increasing trend with raising pH. Aqueous solution diluted make mutual attraction between sulfonic acid group and quaternary ammonium group or tertiary amine group weakened, and the conformation becomes loose, leading to reduced viscosity increasing. The ability of monovalent and divalent catonic charges influencing the viscosity of ampholytic polyphenylene sulfide obeys the following sequence: NH4+ References | Related Articles | Metrics