Optimization of the Amount and Molecular Weight of Dispersing Agent PEG During the Co-Precipitation Preparation of Nano-Crystalline C-YSZ Powder.

Single-phase nano-crystalline yttria-stabilized zirconia (YSZ) powder was prepared by co-precipitation method using zirconium oxychloride (ZrOCl2 · 8H2O) and yttrium nitrate (Y(NO3)3 · 6H2O) as raw materials and ammonium bicarbonate (NH4HCO3) and liquor ammonia (NH4OH) as the precipitators. In order to get the powder with favorable dispersibility, polyethylene glycol (PEG, HO(CH2CH2O) n H) with different molecular weights and amounts was used as a dispersant agent in the synthesis process and its effects on the YSZ powder was investigated. The scanning electron micrograph (SEM) images showed that the degree of agglomeration and the mean crystal size of YSZ powder varied with the amount and the molecular weight of PEG. The appropriate amount and molecular weight of PEG were given by comparing the dispersibility and crystal size distribution of powders. In the process, one also could find that the promotion of dispersion was insensitive to the molecular weight, and all PEG (400­2000) can exert an ability to reduce the agglomeration. The proper amount of PEG400, PEG600, PEG1000, PEG2000 was 3 wt%, 3 wt%, 2 wt%, 2 wt%, respectively. The transmission electric microscope studies in conjunction with the XRD analyzes verified the low degree of agglomeration and the size of YSZ powder varied between 10~20 nm.