Comparison of structure and phase change characteristic of microencapsulated core/shell Al–Si alloy microparticles synthesized by two methods

Pre-oxidation process and modification with silane coupling agent (SCA) of original Al–Si alloy particles were selected to synthesize inorganic microencapsulated core/shell Al–Si alloy microparticles based on the sol–gel technology, respectively. The microstructure and phase change characteristic were measured and investigated by means of Fourier transform infrared spectra, X-ray diffraction, scanning electron microscopy, thermogravimetry and differential scanning calorimeter. These two methods can both realize the microencapsulation and form stable dense α-Al₂O₃ shell. It is speculated that the microencapsulated reason is mainly attributed to the change in surface electric behaviors of Al–Si alloy particles according to the results of zeta potential measure. The latent heats are 416.92 and 307.21 kJ/kg for specimens treated by pre-oxidation and the modification of SCA, respectively. The latter renders thicker and more uniform shell layer.