Role Of Metal In Refractory Materials

Metal as a group of elements is applied in the refractory, besides the effect of reinforcing and toughening matrix material, and it has the effect of plastic molding, promoting the sintering and oxidation resistance.
 

Plastic molding: Metal in the stress of the lattice will be a slip which has the plastic molding, so putting the metal into refractory will make the higher density product than that without adding metal samples under the same forming pressure.

Promoting the sintering: The metal to the refractory material to promote the sintering effect can be attributed to two factors: the first one is that the plastic phase formed by metal forming can improve the density of the body, shorten the distance between the particles, and reduce the energy needed for the diffusion in the process of firing; the second one is that the melting point of metals is generally lower than that of refractory materials, which can produce liquid at a lower temperature, and the capillary force of liquid phase formation and the viscous flow of the liquid can accelerate the transfer rate of the atom and the shrinkage of the body.

Improving toughness: The metal is through crack bridging, crack deflection and crack barrier mechanism to improve the toughness of the composites. The crack bridging is most effective toughening mechanisms, that when the crack expands to the interface of metal material and the matrix material, because of the ductility of the metal particles, crack makes the stress stretch, a bridging stress will be used in the crack surface, on the one hand, it can prevent the crack opening and decrease the strength factor of the crack tip, in addition, it can play a role in toughening as plastic deformation will be happened with the crack opening which consume the crack tip energy.
 

Oxidation resistance: Carbon composite refractory materials have excellent thermal shock resistance and slag resistance due to the existence of carbon, however, there is a defect that it is easy to be oxidized, and once the carbon is oxidized, the advantage will be lost. In order to give full play to the advantages of carbon composite refractory, it is often used to improve its antioxidant properties by adding appropriate additives. Due to the active performance of metal which is easy to react with O2 and CO, so metal has been used as an antioxidant in refractory material. Commonly used antioxidant are Al, Si, Mg and the corresponding alloy, such as Al2O3,SiO2 and MgO can be use in refractory of fused cast AZS block, zircon brick, magnesia brick and other refractory bricks.
 

In conclusion, Metal added into the refractory materials plays a active role on the mechanical properties and oxidation resistance of refractory materials, which indicates that they have a broad application prospect in the refractory materials. With the continuous development of science and technology and the continuous breakthrough in the field of science and technology, the performance of metal composite refractory materials will be continuous optimized and its application scope will be further expanded.