Effect of Polyacrylic Acid Addition on Rheology of SiC‐Al₂O₃‐ZrO₂(3Y) Mixed Suspensions

Abstract

A suspension with good rheology and high stability is crucial for slip casting and gelcasting technology. However, a mixed suspension from two or more different powders usually has bad rheology because of the easy agglomeration of mixed powders caused by the attractive force between the powders with heterocharges. We studied the surface modification of the each single-component powders (SiC, Al 2 O 3 , ZrO 2 (3Y) powders) and the SiC-Al 2 O 3 -ZrO 2 (3Y) mixed powders to increase the repulsive force by adjusting the pH value and adding polyacrylic acid (PAA) as dispersant. The PAA addition effects on the SiC-Al 2 O 3 -ZrO 2 (3Y) mixture were investigated in terms of zeta potential, pH range for heterocharge region, dispersion of the mixed powders and rheology of the mixed slurry based on the study of each unary suspensions. The results show that before surface modification the SiC-Al 2 O 3 -ZrO 2 (3Y) mixed powders were agglomerated severely because they were in the heterocharge region with a broad pH range from 3.5 to 8.25, while after surface modification (pH = 10.5, PAA = 0.8wt%) the heterocharge region was narrowed with a relatively narrower pH range from 2.6 to 3.7. The mixed powders with homocharges were dispersed well because of the great electrostatic repulsive force and steric hindrance offered by PAA and the mixed suspensions had favorable rheology. *zhangning5832@163.com

Effect of surface modification on silicon carbide particles with nanocrystalline spinel LZO for enhanced damping and mechanical property

“…In present scenario, great challenge for the researchers is to attain good stability and proper dispersion of the SiC particles in aqueous solution for the formation of SiC ceramics or SiC reinforced composites. Surface modification of SiC particles have immense effect on rheology and stability of suspensions and provide effective control on the microstructure of suspension-based ceramic green forming [12]. Thus improved properties and desired functionality of the composite materials can be achieved by governing the surface morphology.…”

Effect of surface modified silicon carbide particles with Al2O3 and nanocrystalline spinel ZnAl2O4 on mechanical and damping properties of the composite

“…In present scenario, great challenge for the researchers is to attain good stability, proper dispersion of the SiC particles, prevention of undesirable chemical reactions and poor adhesion between the reinforcement and the matrix for the formation of SiC ceramics or SiC reinforced composites [9][10][11][12]. Surface modification of SiC particles have immense effect on rheology and stability of the particles and provide effective control on the microstructure of suspension-based composite green forming [13].…”

Role of Low Molecular Weight Polymers on the Dynamics of Silicon Anodes During Casting

“…The addition of a dispersant to Si+LiPAA slurries has a much different effect than that observed in the Si+PAA slurries. All parameters for Si+LiPAA with and without dispersant are the same at 0 Hz, which suggests that the dispersant does not greatly affect the general structure of the slurry (Figure 6 and 7), which could be because the dispersant (i. e. dispersion forces) is not able to overcome the hydrodynamic forces in the slurry [15] or that the dispersant is not effectively separating the silicon as evidenced by the decrease in the magnitude of the zeta potential (Figure 2) when compared to silicon powder alone. This points to a fundamental difference in how neutralized low molecular weight polyelectrolyte species affect the structure of the slurry.…”

“…Although low molecular weight dispersants are often included in ceramics processing, this approach has not been widely applied to battery materials. In the processing of oxide‐based powders, such as, barium titanate, silica, alumina, mullite, yttria stabilized zirconia ceramics, a small amount (less than 1 wt %) of a low molecular weight polymer or small molecule, such as citric acid, is often added to a slurry to prevent flocculating, separating, and control flow behavior [8–16] . Dispersants function by steric stabilization which occurs when the dispersant adsorbs onto the particle, creating a repulsive force that physically separates the particles [17–19] …”