Vliv slinovacího cyklu na mikrostrukturu oxidových keramických materiálů

Effect of sintering schedule on grain size of oxide ceramics

journal article - other

en

The sintering and grain size of sub-micrometric CeO2 and ZrO2 + 3 mol%Y2O3 prepared by injection moulding and cold isostatic pressing were studied. Using combinations of the ceramic powders used and shaping methods, three types of bodies were prepared that were characteristic by their own green body microstructure. Their sintering behaviour was described with the aid of high-temperature dilatometry. Each type of specimen was then sintered to two levels of final density (higher than 98% t.d.), for each density always via two or three different firing modes differing in temperature and holding time. In the ZrO2 specimen it was verified statistically that the final grain size was the same irrespective of whether the given final density was obtained by sintering for a longer period at a lower temperature or for a shorter period at a higher temperature. This finding did not hold for the injection moulded CeO2 cylinders, which contained cavities in the order of millimetre. When these defects in the structure of CeO2 ceramic were removed, it was verified statistically also for this material that the final grain size was a function of the density obtained and not the temperature cycle with which this density was obtained.

Bylo studováno slinování a velikost zrn submikrometrických CeO2 a ZrO2+3mol%Y2O3, připravených injekčním vstřikováním a izostatickým lisováním. Kombinací použitých keramických prášků a tvarovacích metod byly připraveny tři typy těles charakteristických svou vlastní mikrostrukturou green body. Jejich slinovací chování bylo popsáno s pomocí vysokoteplotní dilatometrie. Každý typ vzorku byl poté slinut na dvě úrovně konečné hustoty (vyšší než 98%t.d.) a to na každou hustotu vždy dvěma nebo třemi různými vypalovacími režimy, lišícími se teplotou a délkou prodlevy. U vzorků ZrO2 bylo statisticky ověřeno, že konečná velikost zrn byla stejná bez ohledu nato, jestli bylo dané konečné hustoty dosaženo slinováním po delší dobu při nižší teplotě nebo po kratší dobu při vyšší teplotě. U injekčně vstřikovaných CeO2 válců, které obsahovaly dutiny v řádu až milimetrů, toto zjištění nebylo platné. Jakmile se podařilo defekty ve struktuře CeO2 keramiky odstranit, pak také pro tento materiál bylo statisticky ověřeno, že konečná velikost zrn byla funkcí dosažené hustoty a nikoliv teplotního cyklu, kterým bylo této hustoty dosaženo.

The sintering and grain size of sub-micrometric CeO2 and ZrO2 + 3 mol%Y2O3 prepared by injection moulding and cold isostatic pressing were studied. Using combinations of the ceramic powders used and shaping methods, three types of bodies were prepared that were characteristic by their own green body microstructure. Their sintering behaviour was described with the aid of high-temperature dilatometry. Each type of specimen was then sintered to two levels of final density (higher than 98% t.d.), for each density always via two or three different firing modes differing in temperature and holding time. In the ZrO2 specimen it was verified statistically that the final grain size was the same irrespective of whether the given final density was obtained by sintering for a longer period at a lower temperature or for a shorter period at a higher temperature. This finding did not hold for the injection moulded CeO2 cylinders, which contained cavities in the order of millimetre. When these defects in the structure of CeO2 ceramic were removed, it was verified statistically also for this material that the final grain size was a function of the density obtained and not the temperature cycle with which this density was obtained.

oxidová keramika, slinování, velikost zrn

oxide ceramics, sintering, grain size

2005

01.01.2005

Springer

0022-2461

Journal of Materials Science

40

11

9