Research On Composition, Structure And Properties Of Al₂O₃-Spinel-SiC-C Based Refractory

At present, Al₂O₃-SiC-C based castable is widely used in large and medium-scale iron runner of blast furnace. And this type of castable has obviously improved the service life of iron runner. With the development of metallurgical technology of blast furnace, various metallurgical technology of blast furnaces have been adopted extensively, the working environment of iron runner refractory worsens day by day. So the new requirement to the serviceability of Al₂O₃-SiC-C based castable has been put forward. Spinel have some merits e.g.:high melting point(2135℃), well resistant to high-temperature melt, and good thermal shock resistance, meanwhile, spinel can absorb FeO in slag, which can reduce the erosion of FeO to material. So, introducing magnesium-aluminium spinel to Al₂O₃-SiC-C castable for iron runner is one aim of this thesis.In addition, with the progress of metallurgical technology and the increases of continuous casting capabilities, refining technology of external furnace is applied widely. The expanding of the containing of ladle, the raising of molten steel temperature and the extending of residence time limit the service conditions. The aluminium-magnesium carbon brick used extensively for ladle that has disadvantages that heavy of after-expansion , high coefficient of heat conductivity, high carbon content,at present, is easy to cause deformation of ladle and increase the content of carbon of molten steel ,and then polluted molten steel. According to the need for continuous casting and clean steel , developing long-life and light pollution high-quality ladle inner refractory is significant. The research work of this thesis is mainly included two parts:1. The influence of binder, MgAl₂O₄ and SiC on the properties of Al₂O₃-MgAl₂O₄-SiC-C castable is studied. The results show that the slag resistance of the samples usedα-bond as binder is optimum, while the slag resistance of the samples used traditional calcium aluminate cement and SiO2 micro powder is not very well. With the increase content of MgAl₂O₄, slag resistance is enhanced. With the increase content of SiC, slag resistance is enhanced, but the strength decrease. In the meantime, as the grain size of SiC increase, the slag resistance of samples is also increased, but the strength will increase after it drops first.2. The effect of the content of Si-powder and the carbon on the property of Al₂O₃-MgAl₂O₄-SiC-C material is studied. The results show that as the increase of the Si-powder, the HMOR, thermal shock resistance, oxidation resistance of the sample as well as the slag resistance are all improved. And the linear change rate of the sample is tend to reduce. The linear change rate of the sample that added in carbon black is higher than that of added in graphite, and theβ- SiC produced is to be much more.