粒度对微米级AlH3理化性能及稳定性的影响OA

To investigate the physicochemical properties and stability variations of micrometer-sized aluminum hydride(AlH3)with different particle sizes,three AlH3 samples with D50 particle sizes of 13.1,21.4,and 84.7 μm were characterized.Elemental analysis and X-ray diffraction(XRD)were adopted to characterize variations in crystal structure and chemical purity.Scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS)were utilized to analyze morphological features and surface elemental composition.Isothermal and non-isothermal thermal analyses were performed to evaluate discrepancies in thermodynamic stability.The results reveal that all three samples are α-AlH3 with chemical purity higher than 95%.AlH3 specimens of varying particle sizes possess analogous surface elemental compositions,whereas prominent distinctions exist in the crystalline surface morphology.The fine-particle AlH3(D50=13.1 μm)contains fewer surface defects and displays a microstructure nearly identical to the ideal crystalline structure of α-AlH3.As the particle size of AlH3 increases,the number of crystalline surface defects rises,and severe particle agglomeration is observed for the coarse AlH3 sample with a D50 of 84.7 μm.The apparent activation energies for non-isothermal thermal decomposition of the three graded AlH3 samples are all approximately 95 kJ/mol,presenting no statistically significant difference.Nevertheless,remarkable disparities are identified in the isothermal hydrogen desorption rates among the three samples.After isothermal aging at 50℃ for 10 days,the hydrogen desorption ratios of AlH3 with D50 values of 13.1,21.4,and 84.7 μm reach 0.054%,0.104%,and 0.136%,respectively.