The role of metals aluminum in refractory materials:
Plastic phase forming: The metal lattice will slip under the action of stress, which has plastic characteristics. Compared with the hard inorganic material particles, it will play the plastic forming characteristics during the forming process, so that the same The density of the green body prepared under the forming pressure is higher than that of the sample without metal addition.
Promote sintering: The sintering effect of metals on refractory materials can be attributed to two factors:
First, the introduction of metal-forming plastic phase molding can increase the density of the green body, shorten the distance between particles, and reduce the energy required for diffusion and mass transfer during the firing process;
Second, the melting point of metals is generally lower than that of refractory materials, which can generate a liquid phase at a lower temperature. The capillary force formed by the liquid phase and its own viscous flow accelerate the migration rate of atoms and the shrinkage of the green body, which promotes The densification process of sintering.
Improve toughness: Metals can improve the toughness of composite materials through mechanisms such as crack bridging, crack deflection, and crack barrier. Among them, crack bridging is the most effective toughening mechanism, that is, when cracks propagate to the interface between metal material and matrix material, Due to the ductility of the metal particles, the cracks make the stress elongate, which will exert a bridging stress on the upper and lower surfaces of the crack. On the one hand, it can prevent the crack from opening and reduce the strength factor of the crack tip. The plastic deformation occurs at the opening, which consumes the energy of the crack tip and plays a role in toughening.
Oxidation resistance: Carbon composite refractories have excellent thermal shock resistance and slag resistance due to the presence of carbon, but there are defects that are easily oxidized. Once carbon is oxidized, its advantages will be lost. In order to give full play to the advantages of carbon composite refractories, it is often by adding appropriate additives to improve its oxidation resistance. Due to its lively performance, metal is easy to react with O2 and CO, etc. It has been used as an antioxidant in refractory materials. Al, Si, Mg and corresponding alloys are commonly used as antioxidants.
In-situ reaction to generate non-oxide: introduce metal into refractory material, during the firing process, use it to react with raw material components or surrounding gas to generate non-metallic reinforced and toughened phase, which can improve the performance of the substrate at normal temperature and high temperature and resistance Thermal shock and other effects. At present, this technology has received extensive attention.
It can be seen from the above that the addition of metals to refractory materials has a positive effect on the mechanical properties and oxidation resistance of refractory materials, which indicates that they have broad application prospects in refractory materials. With the continuous development of science and technology and the continuous breakthroughs in the scientific field, the performance of metal composite refractories will continue to be optimized, and its scope of application will be further expanded.
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