Views: 0 Author: Site Editor Publish Time: 2022-07-29 Origin: Site
Electric furnace is a heating furnace that converts the electric energy in the furnace into heat to heat the workpiece. Electric furnaces can be divided into resistance furnaces, induction furnaces, electric arc furnaces, plasma furnaces, electron beam furnaces, etc. The electric furnace roof is generally made of high-alumina refractory materials. In the past, the electric furnace cover was mostly built with refractory bricks. Nowadays, high-alumina castables are mostly used for integral casting on site or prefabricated off-site. The castables for electric furnace cover mainly use corundum and bauxite as refractory raw materials, add mullite and other admixtures, and prepare according to the formula proportion.
1. High alumina castables
High alumina castable has many advantages, such as thermal shock resistance, erosion resistance, erosion resistance, spalling resistance and slag resistance, etc. It can adapt to the working environment of the electric furnace cover. When using the electric furnace cover, whether it is prefabricated or cast on site, high-alumina castables can be used as raw materials for construction, and the electric furnace top and refining furnace cover can be processed successfully. Whether it is a circular furnace cover or a triangle, the construction operation can be carried out according to the size and thickness of the electric furnace cover. The electric furnace cover cast with high alumina castables has many advantages, such as good integrity and convenient construction.
2. Cement castables
Among them, the electric furnace cover is prefabricated with cement castables, which has high cold and hot state strength, good thermal shock stability, long life, resistance to steel slag and high-temperature airflow erosion, high-temperature arc radiation resistance, and resistance to the airflow formed by high-speed dust extraction in the furnace. wear characteristics.
3. Steel fiber refractory castable
Because the electric furnace cover works under the condition of high temperature erosion and rapid cooling and rapid heating, the use conditions are quite harsh. Masonry with high-alumina bricks is easy to peel off due to the presence of electric-grade holes, while steel fiber reinforced castables have excellent thermal shock resistance, excellent resistance to high temperature melt erosion, and good volume stability at high temperatures. it is good.
Adding a certain proportion of heat-resistant steel fiber to the castable can improve the stress resistance of the castable, improve the toughness of the castable, and the steel fiber castable has good thermal shock stability, cracking resistance and spalling resistance. Reasonable maintenance after construction can better prolong the service life of the furnace cover.
The performance of the steel fiber-resistant castable is better than that of the first-grade high-alumina brick. When the steel fiber castable is produced, pay attention to using new cement to prepare it with good fluidity, because the compressive strength and flexural strength of the castable prepared with old cement will decrease after drying. The fluidity and setting speed are also not as good as new cement.
Therefore, when preparing and producing castables, newly produced cement must be used as a binder to enhance the strength and tensile capacity of steel fiber refractory castables.
4. Fired high alumina bricks
The service life of high-alumina bricks fired on the lid of an ordinary small electric arc furnace is generally in the range of 60 to 120 heats. There are holes in the center area of the electric arc furnace cover for inserting electrodes and adding some metallurgical auxiliary materials. It does not directly contact molten steel, but it is exposed to strong thermal shock, high temperature and dust erosion. The low melting point and high iron oxide dust interacts with the refractory material of the electric arc furnace cover to generate a liquid phase and promote the sintering of the surface of the refractory material of the electric arc furnace cover. , resulting in cracks between the sintered layer and the non-sintered layer, and strong thermal shock and erosion on the triangular area of the arc furnace cover when the arc light radiation and electrode extraction and insertion above 2000 ° C produce great thermal stress. It promotes the layer-by-layer peeling of the electrode hole surface and lower part in the triangular area, which is the main reason for the damage of the electric arc furnace cover.
Small electric arc furnace cover has less water cooling area, which may also be one of the reasons for the technical name of refractory bricks with low service life of fired high-alumina brick furnace covers.