PENGARUH METODE PREPARASI BROTH DAN JENIS PREKURSOR ZIRKONIUM PADA KARAKTERISTIK KERNEL YTTRIA-STABILIZED ZIRCONIA (YSZ)

Abstract

THE INFLUENCE OF SOL PREPARATION METHOD AND TYPE OF ZIRCONIUM PRECURSOR ON THE CHARACTERISTIC OF YTTRIA-STABILIZED ZIRCONIA (YSZ) KERNEL. Fabrication of yttria-stabilized zirconia (YSZ) kernel by external gelation method has been done. Urea was used in the broth preparation to serve as: 1) as homogenous precipitation agent to produce sol when added at decomposing temperature of urea and 2) as pore promoter when added at below decomposing temperatures of urea. The research used urea in varied mol urea/metal ratio to obtain an the optimum value based on the resulted morphological properties of the sintered kernel. The zirconium precursor used was zirconium oxynitrate hydrate. Characterization of the kernel products include examination with SEM to study the morphological properties of the dried and sintered kernels, measurement of diameter and density of the sintered kernel, and XRD examination to determine the phase of the resulted solid solution of zirconium-yttrium oxide. Based on the
morphological examination, the optimized addition of urea according to its function: 1) as precipitation agent in the sol preparation, mol urea/metal ratio of 1.0 at decomposing temperature of 80^oC and 2) as porosity generation in the gel microsphere, mol urea/metal ratio of 1.5 at addition temperature of 50^oC. The XRD examination shows that a mixture of 16% mol yttrium nitrate dan 84% mol zirkonium nitrate has resulted in solid solution of Y_0,15Zr^0,85O_1,93 or 92ZrO₂.8Y₂O₃ kernels with cubic phase. Increase in precursors concentration in broth has resulted in increase in the diameter of the sintered YSZ kernel, where kernels with average diameter of 0,510 mm was obtained from 0,855 mol/L precursors in broth. Kernels with desired diameter can be prepared by tuning of precursors concentration in broth.