This experiment investigated the effects of sodium based bentonite, sodium carboxymethyl cellulose (CMC), white latex, and sodium tripolyphosphate on the suspension rate and viscosity of water-based casting coatings, as well as their interactions.

Experiments have shown that sodium based bentonite and CMC can significantly improve the suspension rate and viscosity of coatings; White emulsion reduces the suspension rate of the coating, but increases its viscosity; Sodium tripolyphosphate not only reduces the suspension rate of coatings but also reduces their viscosity. It was found that there is an interaction between them on the suspension rate of the coating, while there is no interaction on its viscosity.

Water-based casting coatings are low-cost, safe and reliable, with stable performance, convenient transportation, clean and pollution-free. They are widely used in sand casting, metal casting, centrifugal casting, lost foam casting, and other fields, and are one of the future development directions of casting coatings. In the production of water-based casting coatings, the most commonly used inorganic suspending agents include sodium bentonite, organic suspending agents include sodium carboxymethyl cellulose (CMC), thickeners include white latex, and binders include sodium tripolyphosphate. But research on the impact and interaction of these auxiliary materials on the most important technical indicators of coatings - suspension rate and viscosity. In this study, neutral bauxite was selected as the aggregate for water-based coatings, and the effects of additives such as sodium bentonite, CMC, white latex, and sodium tripolyphosphate on the suspension rate and viscosity of the coatings were studied, providing reference for the research of water-based casting coatings.

Experimental materials and methods: bauxite, 320 mesh; Sodium based bentonite; Sodium carboxymethyl cellulose (CMC); Sodium tripolyphosphate; White latex; Wetting agent: OP-10; Defoamer: JFC.

The suspension rate of the coating is determined by using a 100mL cylindrical measuring cylinder and settling for 6 or 24 hours; The viscosity is determined using a 100mL, quasi 6mm flow cup method. Sodium based bentonite, white latex, CMC, and sodium tripolyphosphate are induced and dissolved using a specific process before use to produce a slurry, which is then used 72 hours later.

Conclusion:

1. White latex significantly increases the viscosity of the coating, but reduces its suspension rate; Sodium based bentonite and CMC improve the suspension rate and viscosity of coatings; Sodium tripolyphosphate not only reduces the suspension rate of coatings, but also reduces their viscosity.

2. From the influence of these four additives on the suspension rate and viscosity of coatings, it can be seen that there is no corresponding relationship between the suspension rate and viscosity of coatings.

3. There is an interaction between sodium tripolyphosphate and sodium based bentonite, sodium tripolyphosphate and white latex, sodium based bentonite and CMC on the suspension rate of the coating, but no interaction on its viscosity.

4. When examining the 6-hour suspension rate of coatings, there is a strengthened interaction between CMC and sodium based bentonite in Tongling, while the production and sales of Tongling bentonite include sodium tripolyphosphate and sodium based bentonite, as well as a weakened interaction between sodium tripolyphosphate and white latex.