Binding mechanism of refractory binder

The bonding mechanism of refractory materials varies with the chemical properties of the binders. Usually, there are six typical binding mechanisms. Generally speaking, one kind of binding agent has its specific binding mechanism, but sometimes there will be the phenomenon that several binding mechanisms exist simultaneously. There binding mechanisms can be primary or secondary. This is very important for material design, and sometimes special requirements can be achieved through a certain binding agent with different binding mechanisms.

(1) Hydraulic bonding
It’s a kind of hydration reaction between the binding agent and water at normal temperature. For example, various kinds of cement are bonded through hydration bonding mechanism to make the materials to generate strength.
(2) Chemical bonding
It’s a kind of chemical reaction between the binding agent and the accelerating agent, or between the binding agent and the refractory material at room temperature, or a chemical reaction when heated to form a compound with binding effect. For example, when sodium silicate (water glass) binder is added with sodium fluorosilicate accelerator, they will react and generate the SiO2: nH2O solution, which will form a network structure of siloxane (Si-O-Si) through dehydration and thereby producing a strong binding effect.
(3) Condensation polymerization bonding
It’s a kind of condensation polymerization when the binder is added with catalyst or cross-linking agent to form a network structure to make the materials to generate strength.
(4) Ceramic bonding (sintering bonding)
It’s a kind of sintering bonging method, which is by means of adding auxiliaries or metal powders that can reduce the sintering temperature of the refractory material to greatly reduce the temperature of the liquid phase to promote the solid-liquid reaction at low temperature to generate the sintering bonding at low and medium temperature.
(5) Adhesion bonding
It’s a kind of physical bonding, which will contain one or several kinds of physical reaction. The common physical reaction is as below: 1. adsorption; 2, diffusion; 3, electrostatic effect.
(6) Cohesive bonding
It’s a kind of cohesive reaction, which is by means of the addition of agglomerating agents to make the microparticles (colloid particles) to generate bond.