Stabilizing of magnesium powder by microencapsulation with azidodeoxy cellulose nitrate

Abstract

• Magnesium powder was coated with azidodeoxycellulose nitrate via solvent/non-solvent method. • FT-IR, SEM and TG/DSC techniques were employed to evaluate quality of the coated particles. • Taguchi robust design was applied to optimize coating process variables. • The significance of coating conditions on thermal stability of coated magnesium was studied. Surface of magnesium particles is highly reactive and may be oxidized easily during storage at ambient conditions. Coating the surface of metal particles with a layer of polymer could be a simple and efficient way to prevent oxidation. In this study, Taguchi robust design was employed as a statistical experiment design for coating of magnesium powder with azidodeoxy cellulose nitrate via solvent/non-solvent technique. FT-IR spectroscopy and scanning electron microscopy techniques were used to evaluate the surface morphology of coated particles. The effect of azidodeoxy cellulose nitrate coating on magnesium powder thermal stability has been investigated by means of thermogravimetry (TG) coupled with differential scanning calorimetry (DSC). The effects of procedure parameters, i.e., type of solvent, percent of polymer as the stabilizer, flow rate of non-solvent addition, and added non-solvent volume in the coating quality and thermal properties of magnesium powder have been studied by thermal analysis methods. Analysis of variance (ANOVA) was employed to evaluate quantitatively the effect of these parameters on thermal stability of coated magnesium particles. Thermal data showed that magnesium powder could be stabilized considerably by controlling coating process parameters including the percent of the stabilizer, flow rate of non-solvent addition, and type of solvent. Based on the ANOVA results, using of 3% stabilizer, 1 ml/min as non-solvent flow rate, and DMF as the solvent are optimum conditions for coating of magnesium particles with azidodeoxy cellulose nitrate leads to producing coated particles with higher thermal stability (567 °C); whereas, TG/DSC analysis results revealed that the main thermal oxidation of the pure magnesium powder starts at lower temperature ranges of 260 °C.