Combination of mechanochemical activation and self-propagating behavior for the synthesis of nanocomposite Al2O3/B4C powder

In this research, Al2O3/B4C nanocomposite was successfully synthesized by combining of mechanically induced self-propagating reaction of aluminum, graphite and boric acid powders mixture. For this purpose the starting materials were activated in a planetary ball mill under Argon atmosphere. The structural evaluation of powder particles was investigated by X-ray diffraction, FTIR spectrometer and scanning electron microscopy (SEM). The effect of activation time on the combustion temperature and the reaction products was discussed based on STA experiments. The results indicated that the reaction between Al and B2O3 (aluminothermic reaction) is highly exothermic and should be in combustion mode. According to XRD analyses, the Al2O3/B4C nanocomposite was fabricated after 4 h of high energy ball milling. Simultaneous thermogravimetric analyzer (STA) results showed that increasing the activation time to 3 h can decrease the temperature of combustion reaction to590 °C. SEM observations confirmed that the range of particle size was within 100 nm.

► Al2O3/B4C has been synthesized starting with Al, B2O3 and C (graphite).
► Reactions occurred in MSR mode.
► By increasing milling time, an exothermic reaction occurs before aluminum melting.
► The quantity of 9Al2O3·2B2O3 extremely decreased with an increase in milling time.
► It was found the particle size below 100 nm after more 4 h.