Influence of dispersant on powders dispersion and properties of zirconia green compacts

Adsorption of water-soluble polymeric dispersant onto zirconia powders together with its influence on powder dispersion and green compact properties of the ceramics were investigated. Three different zirconia powders, each has its own specific particle morphology and surface chemistry (impurity), were employed. Typical Langmuir-type adsorption isotherms were observed for these zirconia powders; however, the isotherm plateau was roughly identical as approaching to maximum specific adsorption of approximately 2.5-2.8 mg per specific surface area of the powders, whilst the initial slopes in the isotherms were distinctly different which appeared to be powder-specific. This may arise from surface chemistry effect as further evidenced by an observation on the pyrolysis behavior of the adsorbance. The particle size and particle-size distribution of the powders generally became smaller and narrower. respectively, when the maximum adsorption was attained. Variation in particle size distribution gives rise to a significant effect on particle packing efficiency in the green-shape consolidates. (C) 2000 Elsevier Science Ltd and Techna S.r.l. All rights reserved.