Effect of high energy ball milling on compressibility and sintering behavior of alumina nanoparticles

The effect of high-energy ball milling on the textural evolution of alumina nanopowders (compaction response, sinter-ability, grain growth and the degree of agglomeration) during post sintering process is studied. The applied pressure required for the breakage of the agglomerates (Py) during milling was estimated and the key elements of compressibility (i.e. critical pressure (Pcr) and compressibility (b)) were calculated. Based on the results, the fracture point of the agglomerates decreased from 150 to 75 MPa with prolonged milling time from 3 to 60 min. Furthermore, the powders were formed by different shaping methods such as cold isostatic press (CIP) and uniaxial press (UP) to better illustrate the influence of green compact uniformity and powder deagglomeration on the densification behavior of nanopowders.