Self-flow characteristics of self-flowing refractory castables

August 13, 2018
The self-flow characteristics of self-flowing refractory castables mainly depend on the particle size composition. In traditional castables, the proportion of aggregates is large, and there are many direct contacts between the aggregates. This contact hinders the flow properties of the materials and requires vibration to flow. . The self-flowing castable contains less aggregate and more matrix, so that there is little direct contact between the aggregate particles, the fine powder forms a continuous fluid with water, and the fluid consists of particles with suitable consistency and high density. It can prevent particle segregation without losing fluidity, so that the material can flow freely under its own gravity.
It can be said that there is no self-flowing castable without a suitable dispersant. A dispersant is a surface active substance whose mechanism of action in a castable is: dissolution in water - formation of a colloid with a certain charge - certain particles that are agglomerated by the matrix (eg CA, SiO 2 , a-Al 203 ) Etc.) Adsorption—The formation of an electric double layer on the surface of the particle creates an electrostatic repulsion between the particles, overcoming the van der Waals force between the particles—distributing the particles—releasing the water encapsulated by the condensed particles—wetting the surface of the particles to impart a certain fluidity . The amount of dispersant generally has an optimum value, and the dispersion effect is not good. When more, the coagulation occurs, the viscosity of the material is increased, and the material loses fluidity. In addition, depending on the matrix material, the type of dispersant used is also different.