Polyurethane was grafted onto the surface of domestic poly-p-phenylene benzobisoxazole (PBO) fiber by atmospheric air dielectric barrier discharge plasma, and the effect of sizing agent on grafting reaction was invetigated. The results of XPS analysis show that the surface chemical composition of PBO fiber modified by plasma grafting polyurethane changed greatly. Compared with the simple air dielectric barrier discharge plasma treated one, the PBO fiber modified by plasma grafting polyurethane had more carboxyl groups, and of which the increment for the later one was 64%~189% (without sizing agent) and 102~184% (with sizing agent) respectively. Sizing agent cannot affect the grafting reaction, and the oxazole ring of PBO was destroyed by plasma grafting reaction. However, ATR-FTIR characterization of PBO fibers with sizing agent showed that the oxazole ring characteristic peaks did not change before and after grafting, so there was no evidence for the destruction of PBO molecules in the near surface. The damage of oxazole ring was detected on the grafted PBO fiber without sizing agent. Thus the sizing agent can prevent the damage of DBD plasma on the near surface of the fiber.
Silicone oil was grafted and modified with allyl polyoxyethylene ether (PEO) and allyl glycidyl ether (AGE) via hydrosilylation reactions to enhance the dispersibility in water of the silicone oil, while proper amount of reactive epoxy groups were introduced in order to prepare aqueous phenolic resin. The structures, as well as the stability and heat resistance of the blends of modified silicone oil and aqueous phenolic resin were characterized by FT-IR, 1H-NMR, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) respectively. In addition, silicone-modified phenolic resin was applied to oil filter paper, of which the micro-morphology, mechanical properties, oil resistance and high temperature resistance were examined. The results show that after being co-grafted with PEO and AGE (3:1 in molar ratio) the silicone has good dispersibility in water, and then, the bland complex of aqueous phenolic resin with 5% (mass fraction) of the co-grafted silicone can forms a three-dimensional network structure with good stability. After being reinforced through impregnation of the above bland complex, the oil filter paper presents greatly enhanced mechanical properties. What is more, the reinforced oil filter paper shows high retention rate of mechanical properties even after soaking in high temperature oil, namely, retention rate of 55%, 63%, and 87% for stiffness, burst strength and tensile strength respectively.
The nucleation-growth type liquid-liquid nano-phase partitioned low-temperature frits were prepared via a two-step process: high-temperature melting and low-temperature heat treatment. The influence of the phase-partition on the gloss, gloss loss, microhardness and other properties of the ABS* lead-free low-temperature frit were assessed by means of high temperature microscopy, differential scanning calorimetry, X-ray diffractometer, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The results show that the size, volume fraction and distribution of the dispersed phase can be effectively adjusted with the aid of appropriate heat treatment processes. The heat-treated frits present microhardness and wear resistance much higher than those of the water-quenched ones. With the increasing heat treatment temperature, the gloss loss of the frits experienced a "Z" shaped variation and the microhardness experienced a reverse trend. Being heat treated at 630℃, the frit presents the smallest gloss loss of 26.4%, the largest hardness of 6202 MPa, whilst its wear resistance can be classified as grade 2 (750 revolutions). The size and the volume of the phase-partition generated dispersive droplets show a downward parabola-like variation as the heat treatment temperature increases. The phase partition facilitates the enrichment of alkali, cerium and boron in the dispersed phase. As the size and volume fraction of the dispersed phases in the frit increases, the free oxygen in the continuous matrix decreases, that is, the O/Si ratio decreases, while the amount of [SiO4] and bridge oxygen increases and the polymerization degree of the network increases. Besides the frit has a dense surface layer, namely the phase-partitioning structure exists inside the frit. The phase rich in alkali, cerium and boron dispersed and embedded in the Si-rich continuous matrix as droplets, in other words the former is protected by the later one. Therefore, the wear resistance and microhardness of the frits were enhanced .
N-doped hierarchical porous carbon (HPCT) was synthesized by adjusting the final activation temperature, with indole as carbon and nitrogen source, CaO as template coupled with KOH activation, and then the adsorption performance of acid orange 74 on HPCT was investigated. BET results show that the surface area of HPCT increases with the increase of activation temperature. The specific surface area of the as-made HPC900 is up to 1629 m2/g when the final activation temperature was 900℃. The FESEM and TEM results demonstrate that the HPCT has the interconnected layer structure. With the rising activation temperature the wall width of HPCT becomes thinner. XPS results show that nitrogen functional groups existed on the HPCT surface, the content of C-NH2 increases gradually as temperature rose. The above functional group is conducive to the π-π stacking effect and electrostatic interaction with absorbate acid orange 74, which is beneficial to the adsorption process. The adsorption isotherm results indicate that the adsorption process could be described by Freundlich model, the equilibrium adsorption capacity of which was more than 270 mg/g by the equilibrium concentration of 50 mg/L. The kinetic results show that the pseudo first-order kinetic equation can better describe the adsorption process, while the physical adsorption is the rate-control step.
A novel inorganic silicate composite coating was prepared by physical blending process with potassium silicate of module 3.25 as binder, alpha alumina, copper chromium black and white mica as pigment, and proper amount curing agent. Then the oxidation behavior of the ZG12Cr9Mo1Co1NiVNbNB (CB2) ferritic heat resistant steel without and with the composite coating was comparatively investigated at 650°C in atmosphere of oxygen flow with 20% water vapors. The results show that serious oxidation of CB2 steel occurred, which follows the parabolic law in different periods and resulted in the formation of a two-layered oxide scale of poorly protective Fe2O3. The application of the composite coating could reduce markedly the oxidation rate of the CB2 steel, meanwhile the coating presented also excellent resistance to cyclically thermal shock. Furthermore, a thin and continuous Cr-rich oxide layer could be detected on the steel surface beneath the composite coating after the oxidation test, to which the enhancement of oxidation resistance of the coated CB2 steel may be ascribed.
The surface suede texture of polysilicon wafer was prepared via NaOH solution etching process. The effect of direction (to which the wafer parallel or perpendicular) and intensity (0, 2 or 4T) of the applied magnetic field on the surface texture of polysilicon wafer was investigated by means of weight loss measurement, Olympus LEXT OLS4100 confocal microscope, ocean Optics USB4000 spectrometer and WT-1200 silicon wafer tester. The results show that with the increase of magnetics intensity the corrosion degree of polysilicon wafer increases, and that the suede texture becomes uniform and finer, whereas the reflectivity decreases. With the same applied magnetics intensity, the motion direction of OH- ions along the magnetic field direction in the alkali solution were not affected by the magnetic field force, however, the Lorenz force generated by the magnetic field acts on OH- ions, when who's motion direction is not exactly in line with the direction of the magnetic field, which then resulted in stronger corrosion for the silicon wafer placed perpendicular to the magnetic field direction, in consequence, the wafer presents much finer in suede texture and stratified structure with longer subatomic lifetime and lower reflectivity, peculiarly the applied magnetics intensity of 4T could make the reflectivity of the wafer lower to 14.5%. In fact, the surface reflectivity of the polysilicon wafer can be significantly reduced when the polysilicon wafer placed perpendicular to the direction of applied magnetic field during the preparation of surface suede texture with the NaOH solution etching process.
Graphene paper films with high mechanical properties and electrical conductivity were prepared by an optimized film forming pressure with graphene as raw material and sodium carboxymethyl cellulose (CMC) as toughening agent. Their mechanical- and electrical-properties were characterized by means of DMA Q800 dynamic thermomechanical analyzer and RTS-8 four-probe tester respectively. The three-dimensional stretched graphene paper of network structure was obtained by surface incision and selective pulling. Then, the stretched graphene paper modified cement-based composites were prepared via multi-step process i.e., injecting the cement slurry of high fluidity, followed by compacting and hardening. The variation of electric resistance of the composite versus applied pressure was measured by a KEITHLEY 2400 digital source meter, while the pressure sensitive property of the composite was also investigated. The results show that the graphene paper film with 50% CMC prepared by an applied pressure of 12.5 MPa has good mechanical strength and electrical conductivity. The prepared cement-based composite with the stretched graphene paper film with 50% CMC presents certain pressure sensitivity, besides its piezo-resistivity exhibits good repeatability even in the condition that the resistance cyclic change rate is 10.29%.
The creep property of 4 nickel-based single crystal superalloys with 4% W, 6% W and 6%W+2%Ru is comparatively studied by creep testing machine, scanning electron microscope, three dimensional atom probe and X-ray diffractometer, aiming to clarify the effect of Ru on the creep performance of the alloy. The results show that the increase in W content will impair the creep performance of the alloy, the creep life of the alloy with 6%W decreases to 58 h at 1070℃/137 MPa. The alloying with Ru can promote the distribution of element W in γ/γ phase more reasonably, whilst inhibit the diffusion of element W from γ phase to γ phase during high temperature creep testing. Therefore, the alloy with 6%W+2%Ru presents a high creep life of 383 h at 1070℃/137 MPa, while no TCP precipitate in the alloy may be observed after high temperature creep testing. During the high temperature creep of the three alloys, the γ phase can form perpendicular to the direction of stress axis, and the TCP phase can destroy the continuity of the raft-like structure, resulting in the increase of the kinking degree of γ/γ phases, which is the main reason for the low creep life of the Ru-free 6%W alloy.
The composite photocatalyst of graphite/TiO2 was prepared by high-energy ball milling with graphite and pure TiO2 as the raw materials. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet diffuse reflectance (DRS). The effect of graphite addition and ball milling time on the photocatalytic activity of the prepared composite photocatalyst was investigated by comparison of their degradation efficiencies for the methyl orange as the simulated pollutant. The results show that after ball milling the graphite/TiO2 composite photocatalyst presents an anatase-like X-ray diffraction pattern, the diffraction peak of TiO2(101) plane widened and shifted to the right, the TiO2 particles are irregular spherical around 200 nm, and the graphite uniformly distributed on the TiO2 surface. Because of higher binding energy of TiO2 grains, the defects generated on the surface of the graphite doped TiO2 have significant absorption capacity in the visible light region. The graphite/TiO2 composite photocatalyst with 5 mass% graphite prepared by ball milling for 12 h showed the best photocatalytic degradation effect of methyl orange. After the degradation time of 70 min the degradation removal rate of methyl orange could reach 95.08%, and the reaction rate constant k was 0.043035 min-1, which was 2.64 times that of the pure TiO2.
CrFeNiAlxSi high entropy alloys were prepared via laser sintering with Al, Cr, Fe, Ni, Si and natural ferrochrome ore powder as raw materials. The effect of Al content on the phase structure, microstructure, density and porosity, microhardness, wear resistance and high temperature oxidation resistance of CrFeNiAlxSi high entropy alloys were investigated. The results show that CrFeNiAlxSi (x=0.2, 0.4, 0.6, 0.8, 1.0) high-entropy alloys composed of BCC+FCC phase. With the increase of Al content, the amount of FCC phase decreases gradually; when x=0.6, the hardness of the alloy reaches 813.3HV and the density of the alloy decreases and the porosity increases; when x=0.2, the density of the alloy is 4.21 g·cm-³ and the porosity is 26.46%; whilst when x=0.6, the wear resistance of the alloy is the best with wear rate of 69.50 mg·cm-²; Furthermore, the high temperature oxidation resistance of the alloy was obviously improved with the increasing Al-content.