Advanced Materials Research Vols. 152-153

Abstract: Mullite was synthesized by firing precursors prepared from kaolinite via a wet chemistry method at various temperatures. The acicular mullite grains were formed in samples with addition of AlF3 by this process. The phase evolution and morphology of the fired samples were investigated. For the samples without AlF3, the mullitization began to occur at 1300 and almost completed at 1550 , the grains formed were normal-shaped. For the samples with AlF3, acicular mullite was formed, and mullitization began to occur at 1100 and completed at 1250 . The growth of the acicular mullite was associated with a liquid phase. The formed acicular mullite was alumina-rich and had a composition of about 73.4 wt% Al2O3 and 26.6 wt% SiO2 (Al2O3/SiO2=1.65, molar ratio).

Abstract: Core-shell nano-Al2O3-coated ZrO2 materials were prepared via a liquid co-deposition method using ZrO2 as cores. Surface of ZrO2 was modified by silane coupling agent. The mechanism of A-151[CH2=CH-Si-(OC2H5)3] was studied under the condition of HAc. The composite powders were characterized by FT-IR, TEM, EDS and SEM. TEM observation confirmed that amorphous Al2O3 layer deposited on the surface of ZrO2 and the thickness of the Al2O3 coating ranged from 5 to 10 nm. After sintered at 1650°C for 10 h, the size distribution narrowed down and the compactness of composite sintered body was better in comparison with pure zirconia.

Abstract: The sphere aluminum hydroxide sulfate and hollow sphere boehmite were synthesized by using urea as precipitator with Al2(SO4)3•18H2O as precursor via a hydrothermal method. The effects of hydrothermal temperature on micromorphology were studied. Results showed that sphere aluminum hydroxide sulfate could obtain on lower temperature. As the hydrothermal temperature increased, sphere aluminum hydroxide sulfate begin to dissolve in situ and recrystallize. In the end, hollow sphere boehmite assembled by flake was formed.

Abstract: At present, there are also very few regarding drill pipe's SCC research in chloride ion ambient medium, so it is specially important to definite the stress corrosion sensitivity of drill pipe to the influence under different chloride ion density and to provide the appraisal basis for the influence of the chloride ion density to drill pipe's corrosion. Applied the G105 drill pipe material to do Slow Stress Rate Testing (SSRT) and the electrochemical experiment under the different chloride ion environment, analyzed the variation of corrosion current and corrosion potential and observed the fracture. The results show that all of the tensile specimens' fracture morphologies are brittle fracture; and the stress corrosion cracking sensitivity of the material increases gradually with the addition of chloride ion concentration; the corrosion rate also tends to increase, but when the chloride concentration is 6000, the corrosion rate is up to a extreme value; the effect of chloride concentration to the cathode is much more than that to the anode, but the G105 pipe corrosion in different chloride solution is controlled differently. The stress can improve the stress corrosion cracking sensitivity of material in corrosion solution. The anti-corrosion principle of chloride ion corrosion is: to reduce adsorption of chlorine ion on the surface.

Abstract: In this paper, a peroxide-tertiary amine oxidation-reduction initiator system was used to synthesize a cross-linked polyacrylamide/bentonite composite at room temperature. The composite could contain up to 50% bentonite. Performance studies showed that the salt tolerance of the composite was enhanced compared to bentonite. The structure of the composite was characterized and analyzed by XRD, FTIR, and TG. Other than a slight increase in the interlamellar spacing, the structure of bentonite did not change during its aggregation. The composite therefore had enhanced dispersion properties and improved thermal stability.

Abstract: Nanometer calcium titanate immobilized on Aluminum oxide (ACTO) was successfully prepared by the citrate acid sol-gel method and characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The adsorption capability of ACTO for Pb2+, Cd2+and Zn2+ from water was studied. Adsorption and elution were investigated under different conditions. The results show that nanometer calcium titanate could be immobilized on the aluminum oxide firmly, becoming a composite adsorbent. The Pb2+, Cd2+and Zn2+ were retained at pH 5-9, their adsorption capacities of ACTO were 124 mg•g-1, 8.58 mg•g-1 and 13.86 mg•g-1, respectively. The adsorption agent can be regenerated by elution with 2 mol•L-1 HNO3. The adsorbent has a promising prospect in removal or enriching and separation of heavy metals in water.

Abstract: Nanocrystalline ZnO powders have been synthesized by a novel combustion synthesis method using glycine and urea as mixed fuels and zinc nitrates as oxidant. The as-synthesized ZnO powders are characterized by DSC, XRD and SEM. Results show that the as-synthesized ZnO powders show well crystalline with hexagonal crystal structure and purity without any other impurities and the particle sizes are about 50~70nm calculated by the Scherrer formula.

Abstract: Solubility is fundamental data of industrial crystallization design, which determine the process conditions, such as feed temperature and crystallization temperature. This article measured solubility of D-Glucurono-1,4-lactone in aqueous and methanol solvent by static equilibrium method, and the experimental date was modeled by ideal solution models; apelblat model; polynomial model and λh model.

Abstract: W and Mo co-doped VO2(M) nanopowders were synthesized by thermal decomposition via two-step method using oxalic acid as reduction acid, vanadium pentoxide as vanadium source, ammonium tungstate and ammonium molybdates as doped sources. The effects of the calcining temperatures and calcining times on the intensities of the diffraction peaks, the grain size and lattice parameters were investigated by means of XRD.

Abstract: The doped and non-doped white Organic light-emitting devices (OLEDs) were fabricated, using strong yellow emitting and hole-transporting ability of TPAHQZn. When the white OLED is a double-doped structure, greatly enhanced the efficiency of the device. The double-doped white device were fabricated as follows: ITO/2T-NATA (17 nm)/ CBP: 30% TPAHQZn: 8% Ir(ppy)3 (25 nm)/ NPBX (15 nm)/BCP(8nm)/TPBi: 10% Ir(ppy)3 (15nm)/Alq3 (20 nm)/LiF (1.3 nm)/Al. The double-doped white OLEDs were obtained with Commission International de L’Eclairage coordinates of (0.29,0.28) at 17 V, the maximum current efficiency increaed four times that double-doped white device of 4.12cd/A(8V) than non-doped of 1.03 cd/A (10V) .