Fabrication of NiO coated SiO_2 and SiO_2 coated NiO for the removal of Pb^(2+) ions

We have prepared silica,SiO2coated NiO and NiO coated SiO2by sol-gel method.The physicochemical properties of the desired materials were investigated by surface charge properties,scanning electron microscopy（SEM）,energy dispersive X-ray（EDX） spectroscopy,surface area measurements and X-ray diffraction（XRD） analyses.The point of zero charge（PZC） of the solid was determined by the salt addition method.In coated materials,two PZC values were noted representing the surface charge of their counterparts.The SEM image of SiO2coated NiO displays a uniform coating of silica on the surface of NiO whereas in case of NiO coated SiO2,a honeycomb like appearance was observed with highly porous structures.In the diffractograms of NiO,the characteristic peaks were suppressed in NiO coated silica however,no diffraction peak could be seen in SiO2coated NiO.Batch adsorption technique was applied for the removal of Pb2＋ions from aqueous solution.The sorption trend for Pb2＋ions was observed in the order of NiO coated SiO2〉 SiO2coated NiO 〉 NiO 〉 SiO2.This trend confirms that the coated materials have more sorption capacities than their parent counterparts.

Effects of different CdCl_2 annealing methods on the performance of CdS/Cd Te polycrystalline thin film solar cells

In this paper, the effects of different Cd Cl2 annealing methods, including vapor annealing and dip-coating annealing, on the performance of Cd S/Cd Te polycrystalline thin-film solar cells are studied. After annealing, the samples are lightly etched with 1% bromine in methanol to remove surface oxides. Both annealing methods give Cd Te polycrystalline thin films with good crystallinity and complete structure. For solar cells containing the annealed Cd Te films, cell efficiency first increases and then decreases as the concentration of Cd Cl2 solution used for dip-coating annealing increases, and the optimized Cd Cl2 concentration is 12%. The uniformity of the performance of all cells is analyzed by calculating the relative standard deviation for each parameter. The uniformity of cell performance can be improved dramatically by dip-coating annealing instead of vapor annealing. Most notably, an appropriate concentration of Cd Cl2(12%) acts as a protective layer that is conducive to realizing uniform high-performance Cd S/Cd Te solar cells. According to the location of depletion regions, the Cd Te films treated by dip-coating annealing show a relatively low doping concentration, except for the sample treated with a Cd Cl2 concentration of 6%, which is consistent with the changes of short-circuit current density of the cells. It is believed that these results can be applied to the large-scale production of Cd Te polycrystalline thin-film solar cells.

Comparative study on microstructure evolution and failure mechanisms of ordinary and refurbished EB-PVD TBC under cyclic oxidation

Refurbishment of thermal barrier coating(TBC)has become a valuable technique to prolong the service life of high-temperature components.This study investigates the effect of the refurbishment process(coating removal and recoating)on the microstructure evolution and physical properties of TBC,including oxidation characteristics,element diffusion behavior,and crack failure mechanisms.The results showed that a certain amount of interdiffusion zone(IDZ)with Cr-rich would be retained in DD6 superalloy substrate after coating removal.The microstructure of the refurbished specimens showed equiaxedβ-NiAl phases,while the ordinary specimens have elongated grain shapes with a high aspect ratio.Moreover,mixed oxides in the refurbished TBC specimens were earlier observed during cyclic oxidation,with a greater thickness compared to ordinary TBC,due to the influence of BC layer phase sizes.The growth mechanism of thermally grown oxide(TGO-Al_(2)O_(3)layer)in the refurbished TBC specimens was also different,resulting from the different mechanisms of mixed oxides growth.Furthermore,under cyclic oxidation with water quenching at 1100℃,the cracks in the refurbished specimen tend to occur in the mixed oxides layer,while the cracks in the ordinary specimen occur in the top coat(TC)layer,attributing to the earlier and thicker mixed oxides layer formed in refurbished specimens.