The formation mechanism and distribution of micro-aluminum oxide layer
It is of great significance to study the thermal oxidation process to understand the reaction mechanism of aluminum particle and further its applications in propellants. The physical and chemical properties of micron-aluminum particle were evaluated by scanning electron microscopy, laser particle size analyzer, X-ray diffractometer and inductively coupled plasma atomic emission spectrometer. The thermal oxidation characteristics of the sample were studied by thermal analyzer. The experimental results showed that the initial oxide thickness of the sample was about 3.96 nm, and the calculated values of the specific surface area and the active aluminum content obtained by the established mathematical model were in good agreement with the measured values. The thermal oxidation process of the sample was divided into three stages. When the temperature rose to 1100 °C, the thermal oxidation efficiency of the sample reached 98.55%. With the increase in treatment temperature, dramatic crystalline changes occurred on the surface of the sample: amorphous alumina—γ-Al2O3, α-Al2O3, and the oxide layer thickness increased from 3.96 to 5.72 nm and 31.56 nm up to 320.15 nm. When the temperature reached 700 °C, the outer surface of the oxide layer contained a small amount of α-Al2O3, while the interior consisted of a large amount of γ-Al2O3, indicating that the conversion of γ-Al2O3 to α-Al2O3 occurred from the inside out.
KeywordsAluminum particle Physicochemical characteristics Thermal oxidation characteristics Oxide layer thickness Crystalline transformation and distribution
This work was funded by the National Natural Science Foundation of China (No. 51376160) and the National Natural Science Foundation of China (No. 51706057).
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