The influence of mol ratio of Ce/total in feed solution on the ceria stabilized zirconia kernel sintering product

Cerium stabilized zirconia kernel has been prepared by external gelation method. As the raw materials, solution of Ce(NO₃)₃.6H₂O and ZrO(NO₃)₂.2H₂O are used with variation of ratio mol (Zr/Total) nitrat 12; 24; 36; 48 and 60 % in the feed solution. To obtain a good gel, the key parameters that must be fulfilled are pH sol, feed viscosity, frequency, amplitude and flow rate of feed. In the washing process, the conductivity of last washing water is conditioned at ≤ 20 μS/cm equivalent to 0.001 % by weight of NH₄OH content, considered to be sufficiently good to proceed to the next process. The drying process was carried out under vacuum condition at 80 °C while calcination at 500 °C with a heating rate of < 2 °C in atmosphere. The dried CSZ gel was measured its diameter and physical condition using a digital microscope. Characterization using DTA-TGA showed an endothermic peak at temperatures around 80 °C to 189 °C with mass reduction of 18.75 %, and an exothermic peak with mass reduction of 11.34 %. The endothermic peaks are detected due to evaporation of water and residual ammonia in the gel, while the exothermic peaks due to decomposition of organic compounds and ammonium nitrate in the gel. The best variation of the mole ratio Ce/Total in the calcination and sintering processes until temperature 1350 °C is 12 and 24 %, the gel is still looked not broken or cracked, the calcined gel has an IR spectrum with a vibration frequency at the value of the hydroxyl functional group, nitrate, cerium and zirconium oxide. The sintered CSZ kernel produces a diffractogram in the form of Zirconium Cerium Oxide compound tetragonal crystal structure. (author)