Study On The Methods Of Determining The Metallic Aluminum Content In Aluminum Nanopowders

The aluminum nanoparticles prepared by electrical explosion of wire (EEW) were studied. In the volumetric method, the phenomenon of the incomplete reaction between aluminum and NaOH solution was probably relevant to the ion solvation. Besides, on the basis of traditional titrimetric methods of determining the metallic aluminum content in the aluminum nanoparticles, in this article Permanganatometric and Cerimetric methods were improved, the effect factors of acid degree, reaction time and so on in the system were also discussed, then the content of metal aluminum was determined by the optimal system. Finally the metal oxidation model and Rietveld refinement were used to calculate the metallic aluminum content.In this work, the characterizations of aluminum was tested by TEM,HRTEM,XRD and the results indicated that the aluminum powders by EEW with the sphere shape showed gaussian distribution in a diameter range from 20nm to 130nm. Besides, the aluminum nanoparticles showed a core-shell structure and the Al2O3 cell thickness was 3nm or so.With the volumetric method the metal aluminum content was only about 75.75%, and the reaction between aluminum nanopowders and NaOH solution was incomplete due to the ion salvation.In the Permanganatometric method, ethanol was used as nonaqueous solvent to prevent the reaction between aluminum nanoparticles and water at room temperature. Besides, Fe(NO3)3 as oxidizing agent. The contrast results illustrated that the content can reach the highest when the aluminum powders were 50mg or so, and the concentration and volume of HNO3 were 0.1mol/L and 28mL, the reaction time was 24h. More over, the mechanism of effect factors were discussed.The concentration of sulphuric acid in the ceric sulfate solution had an effect on the metal content in the cerimetric method and it could reach 87.70% when the H2SO4 concentration was 0.15mol/L.The oxidation of aluminum nanoparticles at low temperature could be saturated to a certain extent and the oxide layer stopped growing. For this core-shell structure, the thickness of the oxide layer was assumed 3nm from the HRTEM result. Then the metal content calculated with the method of Mathematics with Calculus was 78.79%. However, this method was also an estimation for some of the nanoparticles may be oxidized completely.The Rietveld refinement was used to calculate the content of metal aluminum phase. The powder diffraction data was collected using X-Ray Diffractomer with step scanning. Then the fullprof program was used to refine the structural parameters and the result showed that the metallic content was 90.44%, while the impurity Mg was detectived with a content of 0.21% in the aluminum nanopowders by EEW.Finally, there was a comprehensive comparison and analysis among these methods to determined the metallic content in the aluminum nanopowders, and the Rietveld refinement was set as a standard to determined more precise.