Preparation of magnesium aluminate spinel by auto combustion route using glycine as fuel and densification study with Cr2O3 addition

The present work deals with the processing and sintering of phase pure Mag–Al spinel by auto-combustion process by using glycine as fuel. Magnesium and aluminium nitrates have been used as the oxidizers and glycine as the fuel. Addition of glycine to the mixture of magnesium and aluminium nitrates results in a series of redox reactions to form a complex which subsequently crystallizes to form spinel at a lower temperature. Mag-Al spinel has been synthesized by varying metal to glycine ratio as 1:2, 1:2.22 and 1:2.5. Variation of Calcination temperature was done from 600 ̊C to 800 ̊C for 2 hours soaking and their XRD analysis were performed to identify the exact starting temperature for obtaining definite phase for pure spinel. The phase pure Mag-Al spinel was formed at 700 °C, for all the composition.Cr2O3 is added to the spinel and densification effect was studied. The effect is highest in the Composition 3 that is metal to glycine ratio 1: 2.5. The highest Bulk density was achieved is 3.52 that is for composition 3. Apparent porosity and shrinkage value was also calculated