With the technical progress of refractory raw material technology and the improvement of refractory performance requirements of related industries, refractory raw materials for refractory products production have developed from the original natural raw materials to the selected natural raw materials, and then to the fire-resistant raw materials synthesized according to the predetermined physical and chemical performance requirements, so as to greatly improve the quality, performance and service life of refractory materials [1 China is rich in the natural mineral resources of Al Si series which can be used as refractory materials. The proven reserves of high alumina bauxite alone are 3.1 billion tons, ranking first in the world . However, compared with refractories such as magnesia and corundum, the high temperature strength of Al Si series refractories is relatively low due to their poor slag resistance and low high temperature strength. Although there have been many studies on the synthesis of Sialon from kaolin There are many reports [4-5], but the raw materials used in the synthesis of Theron are mostly limited to kaolin, and Theron is a metastable phase, its synthesis and use will be limited to some extent. Based on the above reasons, the research on the effective utilization of Al Si natural minerals is carried out, and the synthesis of Al Si natural minerals is transformed into non oxide or non oxide by carbothermal reduction process Oxide system refractory powder is the main method to effectively utilize the natural mineral resources of Al Si system [6-7]
With the development of modern iron and steel industry and the requirement of producing high value-added steel products such as pure steel and ultra pure steel, the traditional magnesia carbon refractories have been seriously challenged. With the decrease of carbon content, the high-temperature performance of magnesia carbon brick is greatly affected, such as thermal shock performance and slag erosion resistance. Adding some substances to refractories can improve its slag erosion resistance and permeability, For example, SiC, si4n3, ZrO2, magnesia alumina spinel and so on [8-10]
In this study, sic2al2o3 system composite powder was synthesized by carbothermal reduction method with wax and natural graphite as raw materials. The influence of temperature on the synthesis of composite powder was investigated. The sic2al2o3 powder was added into low carbon magnesia carbon brick as additive to investigate its anti slag erosion performance and anti-oxidation performance, and the relevant mechanism was discussed
In experiment 111, the raw materials for the synthesis of SiC 2al2o3 composite powder are wax stone and natural flake graphite. The chemical composition of wax stone is shown in Table 1, and its crystalline phases are al2si4o10 (OH) 2, al2si2o5 (OH) 4 and AlOOH. The mass fraction of carbon in natural graphite is 98%. According to the chemical composition of wax stone and the purity of graphite shown in Table 1, the content of wax stone and natural graphite is calculated first Proportioning ratio. Suppose that the SiO2 in the wax reacts with the carbon in the graphite to form SiC, while the Al2O3 remains; at the same time, assuming that in the atmosphere of argon, the reduction reaction between SiO2 and carbon is carried out according to the following formula :
SiO2 ( s) + 3C ( s) = SiC ( s) + 2CO ( g). (1) It can be calculated that the proportioning (mass) ratio of wax and graphite is 100 / 20
After the wax stone and natural graphite are fully mixed according to the ratio, they are placed in a graphite crucible, heated to 1500-1700 ℃ in a r atmosphere, and kept for 4 hours at each temperature. The flow rate of argon in the experiment is 2 L / min.
For the synthesized sample, the change of crystalline phase in the sample with heating temperature was analyzed by X-ray diffraction, and its microstructure and constituent elements were observed and analyzed by electron microscope and element energy spectrum analysis. The chemical composition of the sample was analyzed by fluorescence X-ray diffraction.