Introduction: Finding the Optimal Solution of Rheology
In the high-pressure grouting process, the slurry needs to meet the dual indexes of high solid content (68%-72%) and low viscosity. The key to achieving this goal is the decoagulant. However, simply dispersing the particles is not sufficient, the slurry must also have excellent resistance to settling and stability over time.
I. Inorganic Decoagulant: Classic Electrostatic Stabilization
Inorganic Decoagulant, represented by sodium silicate and sodium carbonate, increases the Zeta potential on the surface of clay particles by releasing anions.
Advantages: Very low cost, can quickly reduce the initial viscosity.
Limitations and Stability Risk: Inorganic salts are very sensitive to impurity ions (e. G., ca²rex, Mg ²rex) in the mud.When the slurry circulates in the pipeline for too long, the phenomenon of "back-thickening" is easy to occur. In the continuous production test, the 24-hour viscosity fluctuation rate of the slurry using only the inorganic decoagulant is usually more than 15%, which increases the risk of uneven wall formation during high-pressure molding.
II. organic polymer decoagulants: steric hindrance and enhanced stability
Polymeric organic decoagulants such as sodium polyacrylate are the first choice for modern high-end molding processes.
Synergistic mechanism: In addition to electrostatic repulsion, its long-chain molecules attach to the surface of the particles to form a barrier layer, resulting in a steric effect.
Stability advantage: This "dual stabilization" mechanism makes the slurry much less sensitive to temperature and shear forces. Even under the condition of high solid content,Also can maintain excellent thixotropy.
III. Original Insights
For complex types such as toilets without ring holes, the organic decoagulant can ensure the uniformity of slurry flow in extremely narrow gaps in the mold and prevent cold joint marks caused by excessive local dehydration.
In order to balance cost and performance,Composite decoagulants become a trend.
Uniformity of filter cake structure: Studies have shown that composite decoagulants optimize particle packing density. According to, such uniformity can reduce the deformation rate after firing by 0.5 or more.
Impact on mold life: Compared to high sodium salt decoagulants,The low sodium compound can reduce the salt crystallization in the micropores of the high pressure resin mold, thus prolonging the life of the mold by 15%-20%.