Synthesis and characterization of MgSO_4·5Mg(OH)_2·2H_2O flake powders

Magnesium oxysulfate （MgSO4·5Mg（OH）2·2H2O） flake powders with an average diameter of 2 ~tm and a thickness of 0.052 μm were prepared using magnesium sulfate and sodium hydroxide as raw materials by hydrothermal synthesis process. The composition, morphology and structural features of the hydrothermal products were examined with X-ray powder diffraction （XRD）, scanning electron microscopy （SEM） and Fourier transform infrared spectroscopy （FTIR）. The experimental results indicate that in the conditions of n（NaOH）/n（MgSO4） of 1.25, the dosage of w（Na3PO4） crystal additives of 1.0% w（MgSO4）, stirring for 5 h at 180 ℃, the morphology of MgSO4·5Mg（OH）2·2H2O products is flaky and laminar, which is a kind of complex magnesium singlecrystal. The recycling of MgSO4 mother liquor was also investigated to make a full use of the materials and reduce disposal. The results prove that there is no adverse effect on the yield and purity of the products.

B-C Bond in Diamond Single Crystal Synthesized with h-BN Additive at High Pressure and High Temperature

The synthesis of diamond single crystal in the Fe64Ni36-C system with h-BN additive is investigated at pressure 6.5 GPa and temperature range of 1300-1400℃. The color of the obtained diamond crystals translates from yellow to dark green with increasing the h-BN addition. Fourier-transform infrared （FTIR） results indicate that sp2 hybridization B-N-B and B-N structures generate when the additive content reaches a certain value in the system. The two peaks are located at 745 and 1425cm-1, respectively. Fhrthermore, the FTIR characteristic peak resulting from nitrogen pairs is noticed and it tends to vanish when the h-BN addition reaches 1.1 wt%. Furthermore, Raman peak of the synthesized diamond shifts down to a lower wavenumber with increasing the h-BN ~ddition content in the synthesis system.

In-situ Synthesis and Catalytic Properties of ZSM-5/Rectorite Composites as Propylene Boosting Additive in Fluid Catalytic Cracking Process

Using rectorite extrudates from calcined rectorite powder as the starting material, a series of ZSM-5/rectorite composites were prepared via the in-situ crystallization method. The physicochemical properties and propylene boosting performance of the resulting samples were characterized by using X-ray diffraction, scan- ning electronic microscopy/energy dispersive spectrometer, N2 adsorption-desorption, and Fourier transformed in/tared spectroscopy of pyndine adsorption, respectively, and assessed by using Daqing atmospheric residue as Iced- stock. The results showed that the ZSM-5/rectorite composites in which the ZSM-5 phase grows inositu as a 2-3 p,m thick layer on rectorite particles have a trimodal microporous-mesoporous-macroporous structure and thus exhibit outstanding propylene boosting performance. Compared with a commercial ZSM-5 incorporated fluid catalytic cracking catalyst, the ZSM-5/rectorite composite incorporated catalyst increased the yield and selectivity of propylene by 2.44% and 5.35%, respectively.

Effects of Re on surface eutectic formation for Ni-base single crystal superalloys during directional solidification

Effects of Re on the formation of surface eutectics have been investigated by using Ni-base single crystal superalloys with different Re additions. It was found that Re promotes the segregation of Al and Ta to the eutectic melt, leading to an increase of the surface and internal eutectics. In addition, the addition of Re also increased the freezing range, the local solidification time, and the permeability of the dendritic network within the mushy zone. These factors ultimately promoted the outflow of the interdendritic residual liquid with the action of solidification shrinkage, and led to the formation of more surface eutectics. In contrast, the addition of Re had no obvious influence on the surface eutectic microstructures.