Introduction: The Microworld Behind The Term
When dealing with high solids slurries, engineers are faced with two tasks: one is to break the charge attraction between the clay particles (decoagulation), and the other is to ensure that these particles are evenly distributed in the suspension without secondary agglomeration (dispersion). Understand the subtle differences between a coagulant and a dispersant,It is a prerequisite for achieving High-Pressure Casting stability.
I. Core distinctions: Focus on mechanisms of action
coagulation agent: focus on the neutralization and repulsion of charge
The primary goal of a decoagulant is to break up the "flocs" formed as a result of Van der Waals forces or charge imbalance ".
Mainly through ion exchange, the divalent cations on the surface of clay particles are replaced by monovalent cations, thereby increasing the Zeta potential.
Representative: sodium silicate, sodium carbonate and other inorganic salts.
Industrial embodiment: They can quickly "liquefy" extremely thick mud, greatly reducing the yield stress.
Dispersants: focus on space barrier and suspension stability
The goal of the dispersant is to ensure that the particles remain independent in the slurry for a long period of time.
In addition to providing electrostatic repulsion, Modern Organic dispersants make greater use of steric hindrance effects. The long-chain polymer adsorbs on the surface of the particles and acts like a brush to prevent the particles from approaching each other.
Representative: organic polymers such as sodium polyacrylate and polymaleic acid.
Industrial manifestation: They impart excellent settling resistance and temperature resistance to the slurry.
II. Internal Connection: From Synergy to Fusion
In the production practice of modern high-pressure grouting equipment, the two have been highly integrated into an "electro-static composite stabilization system".
Synergy and complementarity: the inorganic decoagulant is responsible for "initially opening" the agglomerates and reducing the cost; The organic dispersant is responsible for the "locked" state to prevent the slurry from "thickening" in the pipeline circulation ".
Determinants of filter cake quality: This connection directly affects the compactness of the body. Studies have shown that the use of inorganic coagulant slurry alone,The internal pore distribution of the filter cake formed at 1.2 MPa pressure is uneven, resulting in an increase of 0.8-1.2% in the deformation rate after sintering. After adding the high-efficiency dispersant, the particles are more compact and orderly.
III. Sunlets' Original Insight: The Chain Reaction of Decomposition and Dispersion on Mold Permeability
We have found through long-term observation that,If the dispersant molecular weight is not properly selected, excessively long polymer chains can block the micropores of the mold (about 10-20 μm).
In the high-end OEM production line, we recommend the use of medium molecular weight polyacrylic acid dispersant. This can not only ensure the stability of the slurry, but also ensure that the drainage rate of the mold is not damaged,So as to extend the service life of the mold by more than 20%.