La2O3 and Ce2O3 were penetrated into PbTiO3 to obtain conductive powders, and then they were mixed with polyurethane and butyl acetate to prepare conductive coatings. The results showed that the electric property of m...La2O3 and Ce2O3 were penetrated into PbTiO3 to obtain conductive powders, and then they were mixed with polyurethane and butyl acetate to prepare conductive coatings. The results showed that the electric property of modified PbTiO3 powders was improved by penetration of La2O3 and Ce2O3. XRD patterns showed that some new compounds such as La2Ti6O15, CeTi21O38 and Pb0.634La0.209Ti0.948O2.284 were formed, which led to the rapid increase of conductivity. The resistivity of modified PbTiO3 powders decreased to 3.88 Ω·m. The coatings using modified PbTiO3 powders as fillings also had a good conductivity. When the PbTiO3 powders were 10% and antisettle agent (bentonite) content was 0.50%, and mass ratio between polyurethane and butyl acetate was 1.05, the surface resistivity of the coatings fell down to 1.3×108 Ω·m. This kind of conductive coatings could be used in electromagnetic shielding.展开更多
A new kind of AZO powders were synthesized by co-precipitation method with the doping content of Al was 3.0 wt%. Further modification of La to the powders was done via a gaseous penetration processing. Changes in cons...A new kind of AZO powders were synthesized by co-precipitation method with the doping content of Al was 3.0 wt%. Further modification of La to the powders was done via a gaseous penetration processing. Changes in constitution,structure,and electrical conductivity caused by doping and penetration were characterized. The doping of Al lowered the resistivity of AZO powders from over 1×1014(ZnO made domestically) to 4.24×107 Ω·cm. But more effective modification via gaseous penetration processing decreased the resistivity of La penetrated AZO powders to the lowest point of 2.45×105 Ω·cm. The optimal penetration conditions coordinated by orthogonal test were that La3+ content of the penetration solvent was 2.0 wt.%,and that the penetration processing lasted for 5 h at the temperature of 480 oC. XRD analysis demonstrated that the doping process of Al only leaded to the changes of the peak width and intensity without new phases appearing. Yet,new phases appeared after the processing of gaseous penetration of La,which indicated that La enter the AZO powders thus complex reactions occurred to form the extra compounds. EDAX analysis,coupling with XRD,provided the evidence that La did exist in the penetrated AZO powders and the potential sign of the generation of extra compounds. Through SEM images,it was illustrated that the gaseous penetration processing progressed the growth of grain size in the shape of rod and generated distinguishable phases of extra compounds.展开更多
The objective of this research is to improve the thermal conductivity and mechanical properties of Al/GNPs（graphene nanoplatelets） nanocomposites produced by classical powder metallurgy and hot rolling techniques. T...The objective of this research is to improve the thermal conductivity and mechanical properties of Al/GNPs（graphene nanoplatelets） nanocomposites produced by classical powder metallurgy and hot rolling techniques. The microstructural evaluation confirmed the uniform dispersion of GNPs at low content and agglomeration at higher contents of GNPs. The structure of graphene was studied before and after the mixing and the Raman spectrum proofs that the wet mixing has a great potential to be used as a dispersion method. There was no significant peak corresponding to the Al_4C_3 formation in both the differential scanning calorimetry curves and X-ray diffraction patterns. The microstructural observation in both fabrication techniques showed grain refinement as a function of the GNPs content. Moreover, the introduction of the GNPs not only improved the Vickers hardness of the composites but also decreased their density. The thermal conductivity investigations showed that in both the press-sintered and hot-rolled samples, although the thermal conductivity of composites was improved at low GNPs contents, it was negatively affected at high GNPs contents.展开更多
基金the National Natural Science Foundation of China (20571020)
文摘La2O3 and Ce2O3 were penetrated into PbTiO3 to obtain conductive powders, and then they were mixed with polyurethane and butyl acetate to prepare conductive coatings. The results showed that the electric property of modified PbTiO3 powders was improved by penetration of La2O3 and Ce2O3. XRD patterns showed that some new compounds such as La2Ti6O15, CeTi21O38 and Pb0.634La0.209Ti0.948O2.284 were formed, which led to the rapid increase of conductivity. The resistivity of modified PbTiO3 powders decreased to 3.88 Ω·m. The coatings using modified PbTiO3 powders as fillings also had a good conductivity. When the PbTiO3 powders were 10% and antisettle agent (bentonite) content was 0.50%, and mass ratio between polyurethane and butyl acetate was 1.05, the surface resistivity of the coatings fell down to 1.3×108 Ω·m. This kind of conductive coatings could be used in electromagnetic shielding.
基金Project supported by the National Natural Science Foundation of China (20571020)
文摘A new kind of AZO powders were synthesized by co-precipitation method with the doping content of Al was 3.0 wt%. Further modification of La to the powders was done via a gaseous penetration processing. Changes in constitution,structure,and electrical conductivity caused by doping and penetration were characterized. The doping of Al lowered the resistivity of AZO powders from over 1×1014(ZnO made domestically) to 4.24×107 Ω·cm. But more effective modification via gaseous penetration processing decreased the resistivity of La penetrated AZO powders to the lowest point of 2.45×105 Ω·cm. The optimal penetration conditions coordinated by orthogonal test were that La3+ content of the penetration solvent was 2.0 wt.%,and that the penetration processing lasted for 5 h at the temperature of 480 oC. XRD analysis demonstrated that the doping process of Al only leaded to the changes of the peak width and intensity without new phases appearing. Yet,new phases appeared after the processing of gaseous penetration of La,which indicated that La enter the AZO powders thus complex reactions occurred to form the extra compounds. EDAX analysis,coupling with XRD,provided the evidence that La did exist in the penetrated AZO powders and the potential sign of the generation of extra compounds. Through SEM images,it was illustrated that the gaseous penetration processing progressed the growth of grain size in the shape of rod and generated distinguishable phases of extra compounds.
文摘The objective of this research is to improve the thermal conductivity and mechanical properties of Al/GNPs（graphene nanoplatelets） nanocomposites produced by classical powder metallurgy and hot rolling techniques. The microstructural evaluation confirmed the uniform dispersion of GNPs at low content and agglomeration at higher contents of GNPs. The structure of graphene was studied before and after the mixing and the Raman spectrum proofs that the wet mixing has a great potential to be used as a dispersion method. There was no significant peak corresponding to the Al_4C_3 formation in both the differential scanning calorimetry curves and X-ray diffraction patterns. The microstructural observation in both fabrication techniques showed grain refinement as a function of the GNPs content. Moreover, the introduction of the GNPs not only improved the Vickers hardness of the composites but also decreased their density. The thermal conductivity investigations showed that in both the press-sintered and hot-rolled samples, although the thermal conductivity of composites was improved at low GNPs contents, it was negatively affected at high GNPs contents.
