The effect of polyvinyl alcohol as a binder and stearic acid as an internal lubricant in the formation, and subsequent sintering of spray-dried alumina

The production of ceramic components using fewer processing steps on a shorter timescale is very important when considering the industrial and economic aspects of the manufacture of these materials in bulk. Spray-dried granules are expected to give compacts with fewer defects due to their low shear strength compared to conventional powders. Several extent studies show results for product of high relative densities (∼50% at 10 MPa), however, this study arrives at a process for making ceramic components with comparable density (48–49%) at 10 MPa), using less processing time and fewer processing steps which becomes extremely important when one considers the industrial aspects such as bulk production and manufacturing cost. In the present investigation, 35 vol% alumina slurries with 0.5% weight dispersant (ammonium polyacrylate) have been synthesized with different contents of binder (PVA) and lubricant (stearic acid). It is found that variations in the amounts of these additives plays a significant role in the formation of spray-dried granules, as well as the subsequent consolidation and densification of the compacts made using the granule particles. There is support for adopting the concept of a ‘compact process’.