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Application of metal in refractories
Jan 26, 2018

In recent years, metal composite refractory has become a hot research, such as Si, Al and Fe into the refractory materials, research and development of Si-Si3N4-corundum ceramic cup, Al-carbon-corundum skateboard and Fe-AlN -MgO-Si3N4 composite materials, and some have been in the production of the promotion and application, and achieved satisfactory results, it is worth mentioning that although Si is not a metal, but because of its ductility and ductility and other characteristics of the metal, Often classified as metal materials.

The study shows that once the metal is compounded into the refractory as a component, the metal has the function of forming the plastic phase, promoting the sintering and oxidation resistance, in addition to forming the corresponding compound to enhance the toughening matrix material in an appropriate atmosphere.

The role of metals in refractories:

Plastic phase forming: the metal under the action of stress will slide the lattice, with plastic features, to be introduced into the refractory material, compared with hard inorganic material particles in the molding process will play a plastic forming characteristics, making the same The green density of the samples prepared under the molding pressure is higher than that of the unmetallic samples.

Promote Sintering: The promoting effect of metal on refractory sintering can be attributed to two factors: First, the introduction of metal forming plastic phase forming can increase the density of the green body to shorten the distance between the particles and reduce the diffusion process of mass transfer Second, the melting point of the metal is generally lower than the refractory raw material, which can generate liquid phase at a lower temperature, the capillary force of the liquid phase and its own viscous flow speed up the atom transfer rate and the body Shrinkage, and promote the process of sintering densification.

Improve the toughness: The metal can improve the toughness of the composites through crack bridging, crack deflection and crack barrier mechanism. Crack bridging is the most effective toughening mechanism, that is, when the crack spreads to the interface of the metal material and the matrix material, Due to the ductility of the metal particles, the crack is forced to elongate, which will exert a bridging stress on the upper and lower surfaces of the crack, so as to prevent the crack opening and reduce the strength factor of the crack tip on the one hand, Of the plastic deformation occurs, consume the energy of the crack tip, play a role in toughening.

Anti-oxidation: carbon composite refractory material due to the presence of carbon so it has excellent thermal shock resistance and slag resistance, but there are easy oxidation defects, carbon once oxidized, its advantages will be lost. In order to give full play to the advantages of carbon-based refractory, often by adding the appropriate additives to improve its oxidation resistance. Due to the properties of the metal, it is easy to react with O2 and CO, and has been used as an antioxidant in refractory materials. Al, Si, Mg and corresponding alloys are often used as antioxidants.

In situ reaction of non-oxide: the metal is introduced into the refractory material, in the firing process, the use of its raw material composition or the surrounding gas reaction of non-metallic enhanced toughening phase can be achieved to improve the substrate at room temperature and high temperature performance and resistance Thermal shock and other effects. At present, the technology has received widespread attention.

It can be seen from the above that the addition of metal to the refractory material plays a positive role in the mechanical properties and oxidation resistance of the refractory material, which indicates that they have broad application prospects in refractory materials. With the continuous development of science and technology and the continuous breakthrough in the field of science, the performance of metal composite refractory materials will continue to be optimized, and its application range will also be further expanded.