Introduction
In the process of ceramic manufacturing, the compatibility issue between dispersants and other additives originates from specific chemical interactions between their functional groups. Such interactions may neutralize or interfere with each other's expected effects. Incompatibility can lead to instability in ceramic slurries, alter their rheological properties, and introduce defects in the final product.
Common compatibility issues include:
Interaction with adhesives
Binders are used to enhance the strength of ceramic 'bodies' before firing. Dispersants primarily interfere with binders in two ways: • Neutralization or replacement: Certain dispersants, especially polyelectrolytes, are highly effective because they can firmly adsorb onto ceramic particles. However, they may also displace polymer binders or compete with polymer binders for surface adsorption sites. If the dispersant has a higher affinity for the particle surface than the binder, the binder will fail to adsorb properly, leading to reduced body strength and operational strength. • Dissipative flocculation: When high concentrations of dispersants are mixed with certain binders (e.g., polyvinyl alcohol (PVA)), dissipative flocculation occurs. High concentrations of free polymer chains not only fail to stabilize the particles but instead push them together, causing them to clump. This results in the slurry becoming viscous and unusable. |  |
Interaction with flocculants
Dispersants and flocculants have opposite functions, so their simultaneous use may inhibit flocculation and hinder the dewatering process.
Interaction with surfactants and lubricants
The mixing of anionic dispersants with cationic surfactants leads to charge neutralization. In wet processing, incompatibility between dispersants and lubricants can result in uneven distribution and defects.
Interaction between different substrates
Surfactants are designed for specific substrates (water or solvents), and using them in the wrong type of system will lead to instability and poor dispersion.
How to avoid compatibility issues.
To avoid compatibility issues, please test all additives in the formulation, consider their chemical properties and stability mechanisms, control the order of additive addition, and consult trusted suppliers.
The compatibility between dispersants and other additives in ceramic formulations is key to achieving stable slurry and high-quality products. Interactions such as the adsorption competition of binders, the functional counteraction of flocculants, and the charge neutralization of surfactants can all disrupt slurry stability and lead to product defects. By systematically testing the compatibility of additives, optimizing the addition sequence, and fully considering the chemical mechanisms, compatibility issues can be effectively prevented, ensuring smooth ceramic manufacturing processes and high-quality final products.