Optimized Slurries for Spray Drying: Different Approaches to Obtain Homogeneous and Deformable Alumina-Zirconia Granules

Abstract

Spray drying is widely used for producing granulated feed materials for compaction process, which is the current industrial method for manufacturing alumina-zirconia femoral heads. The optimization of the granules compaction behavior requires the control of the slurry rheology. Moreover, for a dual-phase ceramic suspension, the even phase distribution has to be kept through the atomization step. Here we present two approaches addressing the key issues involved in the atomization of a composite system. Alumina-10 vol % zirconia powders were prepared by either a powder mixing route, or by the surface modification of a commercial α-alumina powder with a zirconium salt. Slurries from both powders were spray dried. The correlation between slurry rheology and pH, granules morphology and sintered microstructures was here investigated and discussed on the ground of the two feed materials characteristics. The processing conditions were optimized to obtain dense and homogeneous alumina-zirconia micro-nano composites by both processing routes.

Mechanism of Reduced Sintering Temperature of Al2O3–ZrO2 Nanocomposites Obtained by Microwave Hydrothermal Synthesis

“…Alumina-toughened zirconia (ATZ) and zirconia-toughened alumina (ZTA) are important materials for high-temperature structural [1,2,3] and medical [4,5,6,7] applications due to their excellent strength and toughness, high wear resistance and temperature stability, and the fact that they are both chemically inert. In order to obtain these properties, the tetragonal metastable phase of zirconia (t-ZrO 2 ) needs to remain stable at room temperature; however, t-ZrO 2 is normally only stable at temperatures above 1170 °C.…”

Synthesis of Al2O3-ZrO2 powders from differently concentrated suspensions with a spray drying technique

“…We previously described the use of Nano Spray Dryer B-90 for the production of Al 2 O 3 and ZrO 2 nanopowders from strong solutions and suspensions [6,7]. Spray drying is widely used for producing granulated feed materials for compaction process, which is the current industrial method for manufacturing aluminazirconia femoral heads [8]. The aim of this work is to evaluate the phase composition and morphology Al 2 O 3 -ZrO 2 nanopowders prepared from the differently concentrated aluminium and zirconium salts in water suspension by means of spray drying technique.…”

Analysis of heat recovery from a spray dryer by recirculation of exhaust air

“…(2), (14), (18) and the relationships T da.in = T ma , the drying air temperature at the heater inlet is given as The energy efficiency of spray drying process is defined as the ratio of the energy required for evaporation of specified amount of water to the energy supplied to the dryer:…”

“…The slurry feed rates were selected on the basis of the small-scale industrial production rates of advanced materials [17]. The range of variation of water content was chosen based on the literature data [18] and our preliminary experimental study on drying of alumina-zirconia composite slurry in a laboratory-scale spray dryer. Other independent parameters were kept constant; ambient air temperature at 30°C and relative humidity at 70%, the product water content at 3 wt% on a wet basis.…”