Papers by Author: Wei Wu

Abstract: We fabricated mono-dispersed β-quartz GeO₂ by microemulsion synthesis at room temperature. The obtained particles were 300 nm sized GeO₂ walnut and hollow waxberry shaped GeO₂ which were consisted of nanosphere with average size of 20 nm. The evolution of high pressure studies were devoted in a diamond anvil (DAC) cell by Angle Dispersed X-ray Diffraction (ADXD) at room temperature. A phase transformation of β-GeO₂ to amorphous GeO₂ was detected in walnut GeO₂, while the waxberry GeO₂ was found to transform to monoclinic phase directly. It is strongly suggested that size effect played a key role in the high-pressure transformation from the amorphous and monoclinic phase. By fitting the compression data to the BirchMurnaghan equation of state, the bulk moduli of the walnut and waxberry shaped β-GeO₂ particles were determined to be 33±5, and 38±4 GPa with B₀ = 3, respectively.

Abstract: Scanning Electron Microscope (SEM) has been widely used in the observation of surface and cross section of materials. So it is important to prepare the cross section of various specimens. In this study, a novel cross section preparation method using argon ion beam (called argon ion beam cross-section polisher or CP) was introduced. This method can not only overcome the problem of artifacts caused by mechanical polishing on the polished surface, but also enable one to prepare a wider area of specimens than the Focused Ion Beam (FIB) method. The soft materials, composite materials with different hardness, multilayer films and powders were all easily polished with few artifacts using this method.

Abstract: The W coatings were prepared by applying the vacuum plasma spraying process (VPS). The phase composition, microstructure and laser irradiation property were characterized by XRD, SEM and laser. Results showed that no tungsten oxide appears in the coatings whose phase composition is similar to the original powder. A better melting state of the coating can be obtained by using the finer powder. The deposition efficiency of the coating is higher in the cases of a higher H2 flow. There is a pitch whose size is about 100μm when the substrate was irradiated by laser. However, there is clearly no change for the W coating surface which was also irradiated under the same condition. It indicates that the laser irradiation resistance is improved significantly for stainless steel after being deposited with W coating.

Abstract: Titanium based anodes are widely used in chlori-alkali industry. Two kinds of titanium based anodes were characterized by using XRD and SEM. The test results of their electrocatalytic properties showed that the nanosize crystals have great effect on the anode’s polarization behaviors and accelerated stability life. The anode with higher content of Ta possessed a smaller crystal size and better electrocatalys

Abstract: TiO2 is a promising photocatalyst due to its excellent photocatalytic activity, physical and chemical stabilities. Plasma spraying technology is good way to prepare for TiO2 coating. The effect of spraying parameters on photocatalytic performance was studied. The results showed that both the amount of unmelted particles and the porosity of as-sprayed TiO2 coatings increased with the increasing of Ar gas flow rate. And the external bias could improve TiO2 coating’s photocatalytical performance. The improvement degree is closed related its grain size and porosity.