Solid loading, ceramics

Mason MS, Huang T, Landers RG, Leu MC, Hilmas GE (2009) Aqueous-based extmsion of high solids loading ceramic pastes process modeling and control. J Mater Process Technol 209 2946-2957... 

This equation is similar to the Cross equation [3] for polymers to be discussed later. The Cross equation is also one of the key constitutive equations for ceramic suspensions at hig solids loading. 

It is obvious that here is a direct correlation between the energy barrier created by the DLVO theory and the viscosity of the system. Due to the importance of viscosity in ceramic processing, those relations have been studied already. Empirical relations have been derived correlating those two magnitudes with temperature and solids loading dependence for Al203 ... 

The ceramic slurry used in DCC consists of a high solids loaded suspension of ceramic particles such as AI2O3 with an enzyme catalyst. An example of an enzyme-catalyzed reaction is shown in Equation 11.36,... 

Wernet, J. and Feke, D.L., Effects of solids loading and dispersion schedule on the state of aqueous alumina/zirconia dispersions, J. Am. Ceram. Soc., 77, 2693, 1994. Nob. J.S. and Schwarz, J.A., Estimation of the point of zero charge of simple oxides by mass titration, J. Colloid Interf. Sci., 130, 157, 1989. 

A freeze-drying process was used to fabricate porous yttria-stabilized zirconia (YSZ) ceramics. Methyl cellulose (MC) was added into the slurry to control the microstructures of the porous YSZ ceramics. The experimental results indicated that the MC concentration and solid loading of YSZ slurry had great influences on the morphologies of pores. After MC addition, the microstmcture of porous YSZ developed from the laminated pores to the reticular pores. Comparison with the MC concentration, the solid loading of slurry had an obvious effect on the porosity. The specimens prepared from 5 to 30 vol% YSZ slurries with 2 wt% MC had porosities from 95.60 to 38.64%. 

In the present work, freeze-drying was used to prepare reticulated porous YSZ ceramics and the methyl cellulose (MC) solution was added in the aqueous ceramic slurry to modify the morphologies of pores. The influences of solid loading and MC concentration on microstmcture, porosity and bulk density were investigated. 

Commercial native tapioca and com starches from Thailand (Tesco) were purchased and used as received. Alumina powder (99.5% purity, Amarin, Thailand), wherein the particle size distribution is shown in Figure 1, was used as the ceramic raw material. Ceramic suspensions were prepared to different % solid loadings with sodium silicate (Amarin, Thailand) as a dispersant, having a fixed concentration of 3 wt.% on a dry alumina basis. The wt.% starch powders were added in different quantities 5 wt.%, 10 wt. %, 15 wt.% and 20 wt.% on a dry alumina basis, which corresponded to 69%, 66%, 63% and 60% solid loadings, respectively. Homogenization was carried out by ball... 

As one would expect, decreasing solids loading results in a lower bulk density, higher porosity and lower strength. Additionally, samples with better physical and mechanical properties can be prepared from tapioca starch at low starch content. There is a little difference in the strength of samples prepared from tapioca and com starches at high starch content Alumina ceramics with porosity of -61% and those with maximum theoretical relative density of 83% can be obtained in this experiment... 

Ceramic particles can be well dispersed in nonaqueous solvent via eleetrosta-tic repulsive forces. In the presence of organic dispersants, the electrostatic repulsive forces can be augmented by steric hindrance from the adsorbed dispersant molecules. The combined hindrances to attraction and coagulation can be very effective in dispersing fine particles and increasing solids loading. 

Liu W, Xie ZP, Bo TZ, Yang XF (2011) Injection molding of surface modified powders with high solid loadings a case for fabrication of translucent alumina ceramics. J Eur Ceram Soc 31 1611-1617... 

Fig. 4.39 SEM images of fracture surfaces of the Y2O3 presintered body calcined at 1000 °C for 2 h (a) and the final ceramics sintered in vacuum at 1850 °C for 6 h (b), which were derived from the slurry of 81 wt% solids loading. Reproduced with permission from [175]. Copyright 2014, Elsevier...

---