Introduction
Dispersants are a widely used surfactant that are extensively applied in the preparation of ceramic slurries. The role of dispersants in ceramic slurries is primarily achieved through electrostatic repulsion and steric stability, with these two mechanisms often working synergistically in a single dispersant (electro-steric stability). Electrostatic repulsion occurs when charged dispersant molecules adsorb onto the surface of particles, forming repulsive forces; steric stabilization arises from the physical barrier formed by the long chains of dispersants, preventing excessive aggregation of particles.
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Mechanism of Action:
| Electrostatic repulsion: | Positional resistance stabilization effect: | Potential resistance stability: | ||
The negatively charged groups of anion dispersants (such as sodium polyacrylate) adsorb onto the surface of ceramic particles. These negatively charged groups repel each other, forming a repulsive force that maintains particle suspension and prevents their agglomeration. When the double electric layers of two particles overlap, this repulsive effect is enhanced. | Long-chain molecular dispersants (such as polyacrylamide) adsorb onto the surface of particles. Segments of the chains extend in the liquid medium, forming a physical barrier around the particles. When two particles approach each other, the extended segments overlap and produce a strong repulsive force, preventing close contact and aggregation. | Many modern dispersants combine two mechanisms to achieve higher stability. Charged groups provide electrostatic repulsion, while long polymer chains produce steric effects. |
Actual working principle
Wettability enhancement: Dispersants enhance the wettability of powders to liquids.
Viscosity reduction: By inhibiting particle agglomeration, dispersants reduce viscosity, thereby improving slurry fluidity and processing performance.
Enhanced stability: The repulsive force generated by dispersants prevents particle sedimentation, ensuring long-term stability of suspensions.
Dispersing efficiency: The effectiveness of dispersants depends on their specific chemical structure, particle surface properties, liquid medium characteristics, and the overall pH value of the slurry.
Dispersants, as a key additive in ceramic slurry preparation, effectively solve process challenges such as particle agglomeration, sedimentation, and poor fluidity through dual stabilization mechanisms of electrostatic repulsion and steric hindrance. They not only significantly reduce slurry viscosity and improve processing performance but also ensure long-term uniformity of the slurry by forming stable double electric layers and polymer barriers. With in-depth research on the interaction mechanisms between dispersant molecular structure and particle surfaces, the development of high-performance and environmentally friendly dispersants will further promote the refinement and efficiency of ceramic manufacturing.