Dispersant is a widely used additive in the preparation of ceramic slurry, because the addition of dispersant can effectively improve the slurry performance and improve the stable dispersion effect. Ceramic dispersant has developed from traditional to many new products today. Sodium tripolyphosphate can disperse, reduce and degumm by itself, which plays an important role in ceramic production.

The basic principle of using dispersant in ceramic slurry is that the dispersant is automatically adsorbed on the solid surface of the slurry, which changes the properties of the interface and reduces the interfacial tension.

The water absorbed by the original particles is replaced by sodium tripolyphosphate as free water into the liquid phase, which is the dilution of the slurry and the increase of fluidity; Under the condition of ensuring the required slurry viscosity (i.e. fluidity), the solid content can be greatly increased, and the solid particles are adsorbed in the micro cracks to generate splitting pressure, which can be separated by increasing the depth of the micro cracks, so as to fully disperse the original agglomerated particles.

Application of sodium tripolyphosphate in degumming agent of ceramic glaze

1. Ceramic grade sodium tripolyphosphate is especially suitable for the dispersion of kaolin and bentonite. 

2. Sodium tripolyphosphate is used as a degumming agent for glazes (such as raw glaze, metal glaze, bottom glaze and matte glaze), which solves the problem of many bubbles during glaze spraying due to the fact that the glaze slurry becomes tofu brain and does not flow. It can be directly added to the mixing bucket of the glaze application line to obtain a smooth glaze surface. 

3. As a dispersant, sodium tripolyphosphate is suitable for the dispersion of coatings, refractories and ridge materials with low clay content.

The principle of adding sodium tripolyphosphate when grinding glaze: the uniformity and stability of ceramic powder particle dispersion system depend on the three main forces when the particles are close to each other.

1. Van der Waals force, which is the attraction between particles. When the particles move to the range of van der Waals force, the particles will attract each other and coalesce.

2. Electrostatic potential resistance, which is the repulsive force between particles. The electrolyte added in the dispersion system is adsorbed on the particle surface with a certain amount of charge to form an electric double layer, increase the zeta potential, generate repulsion, force the separation between particles, and the slurry tends to be dispersed and stable.

3. Steric resistance refers to the addition of uncharged polymer to the dispersion system, which is adsorbed on the particle surface to form a steric resistance layer to prevent particles from colliding and aggregating with each other.

The small particle size, large specific surface area and high surface energy of ceramic slurry lead to the serious agglomeration of glaze particles, which can easily lead to the low hardness, tensile strength and fracture resistance of ceramic body. Therefore, it is necessary to add appropriate sodium tripolyphosphate as dispersant in the process of preparing ceramic slurry to reduce the surface energy of ceramic powder and achieve the effect of uniform dispersion. In the ceramic glaze system with good dispersion, the raw material of ceramic body is the gap between particles, and the sintered ceramic glaze is smoother and more delicate than the traditional ceramic glaze, and the performance of heat resistance and corrosion prevention is better.