Impact of pressure in static and dynamic pressing of ultrafine plasmochemical ZrO2 (Y)-Al2O3 powders on compact density and compaction efficiency during sintering

摘要

The effect of different methods of pretreatment and compacting of ultrafine alumina-zirconia powders of composition (in mass%): 20 Al2O3-80 (ZrO2-Y2O3) on densification processes during pressing and subsequent calcination has been studied. Ultrafine powders were prepared by plasma-chemical method. It was found that the initial nanocomposite is a mechanical mixture made up of zirconia nanoparticles and amorphous alumina in a thermodynamically nonequilibrium state. Grinding of powders did not affect their phase state. Powder compacts were produced by means of uniaxial static pressing and magnetic pulse compaction. The impact of mechanical processing of powders on ceramics density was studied. It was shown that dry grinding of powders in a planetary ball mill does not increase the ceramics density. The best and virtually identical results were obtained using preliminary static pressing of powders at increased pressure P = 900 MPa and their subsequent grinding in a ball mill. Dilatometric studies showed that double-action magnetic pulse compaction provides the maximum shrinkage rate at lower temperatures in comparison to that observed under static pressing. The ceramic density achieved is higher than that obtained using other pressing methods.