PREPARATION OF Y-PSZ CERAMICS OF CONTROLLED PARTICLE-SIZE DISTRIBUTION

Pressing of Y-PSZ powder was performed in a low pressure (4 bar) injec tion moulding equipment at 92 degrees C input material temperature and 2.5 - 7 Pas viscosity range. Model experiments were carried out to el aborate the deparaffination technology of the injection moulded specim ens. The specific surface of the embedding matrix was the chosen varia ble during model experiments. In order to determine the effective diff usion coefficient in the deparaffinating compound, the twice semi-infi nite one dimensional instationary model was used. Using the equation D -eff = f(x) We could also conclude that the deparaffination time can f urther be decreased by establishing a constant wall potential and thus an even more economical technology can be employed. After deparaffina tion the specimens were pre-sintered. Pre-sintered samples were heat t reated in a two-stamped hot press at constant pressure and temperature for 10 - 70 minutes and specimens were investigated to determine thei r physical and morphological properties. Connections between changes i n physical properties, the rate of changes and the duration of hot pre ssing were studied. It was found that hot-pressing process can be divi ded into three periods.