XRD measurements were carried out on plasma sprayed titanates BaTiO_(3),CaTiO_(3),MgTiO_(3)and a mixture of the last two.Samples were tested as dielectrics and volume resistivities of the materials were also summarize...XRD measurements were carried out on plasma sprayed titanates BaTiO_(3),CaTiO_(3),MgTiO_(3)and a mixture of the last two.Samples were tested as dielectrics and volume resistivities of the materials were also summarized.Microwave microscopy was used for mapping of the dielectric response of selected samples.The results show differences in the crystal structure between plasma sprayed coatings and feedstock powders in the case of BaTiO_(3)and MgTiO_(3)whereas CaTiO_(3)is crystalograffically identical with its feedstock.The reason can be found in larger sensitivity of BaTiO_(3)and MgTiO_(3)to the reductive conditions at plasma spraying whereas CaTiO_(3)seems to be rather inert from this viewpoint.However CaTiO_(3)exhibits anomalous dielectric losses because of intrinsic conductivity.展开更多
Titanium dioxide(TiO_(2))was elaborated by four different thermal spray techniques-(i)plasma spraying using a water-stabilized torch,(ii)plasma spraying using a gas-stabilized torch,(iii)high velocity oxy-fuel gun,and...Titanium dioxide(TiO_(2))was elaborated by four different thermal spray techniques-(i)plasma spraying using a water-stabilized torch,(ii)plasma spraying using a gas-stabilized torch,(iii)high velocity oxy-fuel gun,and(iv)oxy-acetylene flame.The porosity of the coatings was studied by optical microscopy,nano-structural features by scanning electron microscopy(SEM),phase composition by X-ray diffraction(XRD);the microhardness,surface roughness and wear resistance were evaluated.The diffuse reflectance was measured by ultra-violet/visible/near-infrared(UV/Vis/NIR)scanning spectrophotometer.The kinetics of photocatalytic degradation of gaseous acetone was measured under a UV lamp with 365 nm wavelength.After all the applied spray processes,the transformation of anatase phase from the initial powders to rutile phase in the coatings occurred.In spite of this transformation,all the coatings exhibited certain photocatalytic activity,which correlated well with their band gap energy calculated from reflectivity.All the coatings offer relatively good mechanical properties and can serve as robust photocatalysts.展开更多
文摘XRD measurements were carried out on plasma sprayed titanates BaTiO_(3),CaTiO_(3),MgTiO_(3)and a mixture of the last two.Samples were tested as dielectrics and volume resistivities of the materials were also summarized.Microwave microscopy was used for mapping of the dielectric response of selected samples.The results show differences in the crystal structure between plasma sprayed coatings and feedstock powders in the case of BaTiO_(3)and MgTiO_(3)whereas CaTiO_(3)is crystalograffically identical with its feedstock.The reason can be found in larger sensitivity of BaTiO_(3)and MgTiO_(3)to the reductive conditions at plasma spraying whereas CaTiO_(3)seems to be rather inert from this viewpoint.However CaTiO_(3)exhibits anomalous dielectric losses because of intrinsic conductivity.
基金This work was supported by the Czech Science Foundation under Project P108/12/1872.
文摘Titanium dioxide(TiO_(2))was elaborated by four different thermal spray techniques-(i)plasma spraying using a water-stabilized torch,(ii)plasma spraying using a gas-stabilized torch,(iii)high velocity oxy-fuel gun,and(iv)oxy-acetylene flame.The porosity of the coatings was studied by optical microscopy,nano-structural features by scanning electron microscopy(SEM),phase composition by X-ray diffraction(XRD);the microhardness,surface roughness and wear resistance were evaluated.The diffuse reflectance was measured by ultra-violet/visible/near-infrared(UV/Vis/NIR)scanning spectrophotometer.The kinetics of photocatalytic degradation of gaseous acetone was measured under a UV lamp with 365 nm wavelength.After all the applied spray processes,the transformation of anatase phase from the initial powders to rutile phase in the coatings occurred.In spite of this transformation,all the coatings exhibited certain photocatalytic activity,which correlated well with their band gap energy calculated from reflectivity.All the coatings offer relatively good mechanical properties and can serve as robust photocatalysts.
