Sliding Plate

Aluminium carbon and aluminium zirconium carbon slide boards
Sliding nozzle is a key device in the continuous steel casting process, and sliding plate is the core component of sliding nozzle device. The selection and composition of skateboard materials are the most basic factors that affect the performance and use effect of skateboard. In order to improve the safety, reliability and use times of skateboard, the materials of skateboard have been optimized and developed since its application.
The plate in the use of harsh conditions are: molten steel erosion, slag erosion (chemical erosion and oxidation), thermal shock, sliding wear; Factors that affect the service life of skateboard are: casting steel, operating conditions, sliding nozzle structure, material, performance indicators, etc. According to the damage form of skateboard, the corresponding relationship with corresponding performance is as follows: sliding surface wear (barren surface) -- the reason is surface oxidation, strength attenuation, wear, inhibition measures are to improve the oxidation resistance, improve the strength, tissue densification; Expanding diameter -- improving anti-erosion ability, tissue densification and low SiO2 content; Hole edge erosion, radial crack - reduce expansion coefficient, reduce elastic modulus. The performance requirements of the skateboard are high thermal strength, wear resistance, slag resistance, anti-spalling, the improvement of the skateboard material changes, corresponding to the improvement of these related performance.
The original boards were ceramic bonded high temperature fired into high aluminum or magnesium boards and impregnated with tar or asphalt for one or more times. Its service life is not very high, mainly because the material's thermal shock resistance and corrosion resistance are not suitable for harsh use conditions. The corrosion resistance of magnesia fired skateboard is better than that of high aluminum skateboard, but the spalling resistance is poor, and the use of the process will become worse, the corrosion resistance in the use of the process will gradually become worse. The high aluminum slide is mainly made of sintered alumina, which is fired at high temperature and impregnated with asphalt. Magnesia-sintered slide boards usually contain 85% to 95%MgO, with a small amount of Al2O3 or spinel added to improve the anti-spalling property. They are suitable for calcium-treated steel with poor thermal shock resistance. They are only suitable for small slide boards and are difficult to be used for large ladles. After the development of aluminum carbon and aluminum zirconium skateboard, according to the treatment temperature, there is no burning aluminum carbon (below 500℃), burned aluminum carbon skateboard (above 1000℃). Compared with fired skateboards, non-fired skateboards contain metal aluminum and have higher thermal strength and corrosion resistance, but the disadvantages are low cold strength, high temperature volume instability, low resistance to peeling, these disadvantages make it not suitable for making large skateboards. The fired skateboard is fired at high temperature, the resin is carbonized to form carbon combination, the added metal combination and reaction sintering to form carbide combination, the performance is excellent, the large size of the skateboard is mainly fired skateboard. Aluminum carbon skateboard than high aluminum skateboard in the use of not only to eliminate the latter due to oil immersion caused by the site of the use of harmful flue gas shortcomings, and has a significantly superior thermal shock resistance, anti-peeling and anti-erosion, especially smaller size of the electric furnace, the middle of the plate showed a significantly high service life. In practical applications, it has rapidly replaced the high aluminum and become the mainstream of skateboard materials. Currently, 90% of the skateboard is made of aluminum carbon and aluminum zirconium carbon. Aluminum zirconium carbon skateboard is based on aluminum carbon skateboard introduced zirconium oxide, improve the performance of the skateboard. This slide introduces low expansion coefficient zirconium mullite aggregate to improve thermal shock resistance and erosion resistance. In addition, zirconium oxide can also be introduced from zirconium oxide or zirconium oxide to further improve the performance of the slide, but the cost and price are also increased accordingly. Table 15-1 lists some basic performance indicators of aluminum carbon slide. Depending on the use conditions (ladle size, casting conditions, etc.), choose different types and sizes of skateboards, small ladle use lower grade non-burning skateboards; Medium ladle made of aluminum carbon or composite aluminum carbon slide plate; Large ladles are made of high grade aluminium carbon or aluminium zirconium carbon slide boards.

Table 15-2 lists the performance indexes of aluminum carbon and aluminum zirconium carbon skateboards for ladle developed by shinagawa corporation of Japan. Svr-a65gz is a common fired aluminum zirconium carbon slide; Other improved slide boards used for ladle use and casting of high erodibility steel are mainly maintained to increase the strength to reduce the waste surface without reducing the thermal shock resistance. The corresponding improvement measures are to use AZTS (al2o3-zro2-tio2-sio2), the raw material with low coefficient of expansion, to reduce the coefficient of expansion and the modulus of elasticity at the same time. Special forms (amorphous carbon) were added to increase cold compressive strength and reduce elastic modulus (e.g. SVR-A75GZ). The use of superfine aluminum oxide powder improves the cold and oxidized compressive strength (e.g. SVR-V55).

High corrosive steel casting slide
Aluminum carbon and aluminum zirconium carbon skateboards are commonly used in steel mills at home and abroad, and some of the high erosive steel, such as Ca treated steel, al-si killed steel, high oxygen steel and other steel using aluminum carbon or aluminum zirconium carbon skateboards erosion serious, service life significantly reduced. When high oxygen steel is poured into common aluminum carbon slide, carbon oxidation and erosion of Al2O3 by infiltration of FeO and MnO occur. When casting high-calcium steel, CaO will react with Al2O3 to produce low melting point al2o3-cao, causing serious erosion. Therefore, the skateboard material to diversify the development, the use of other more appropriate materials, such as low carbon silicon aluminum carbon skateboard and magnesium, spinel, magnesium - aluminum, spinel - carbon, zirconia and other materials slide, respectively suitable for the corresponding special treatment of steel pouring.
Low carbon low silicon with metal aluminum light - fired skateboard
The modified aluminum carbon slide can be used for high oxygen steel casting. Characteristic is to add a certain amount of metal lead in the ingredients, 500~1000℃ medium temperature treatment, not only to maintain the high thermal strength and erosion resistance advantages of the non-burning skateboard, and high cold strength and high oxidation resistance, can be made large size skateboard, the use of high oxygen steel better than burned aluminum zirconium carbon skateboard. At the appropriate heat treatment temperature, Al liquefies to produce a high-strength and dense tissue structure, which significantly increases the corrosion resistance and strength. This skateboard has a good ability to resist crack propagation. Treatment temperature has significant effects on the skateboard performance: the temperature increase, obviously increase the compressive strength, erosion resistance to improve, but more than 1000 ℃ because generates more aluminium carbide and hydration and elasticity modulus increase, the spalling resistance, erosion resistance will decline, so the best for 800 ~ 1000 ℃. This kind of skateboard is presented in table 15-3 (A, B, C, D) and aluminum light burning charcoal skateboard performance comparison.

Alkaline slide board and zirconia Mosaic slide board
Magnesium or magnesiumcarbonized skateboards show higher corrosion resistance and service life when used for continuous casting of calcium-treated steel, high-oxygen steel and aluminum-silicon killed steel, but their disadvantages are poor thermal shock resistance and peeling resistance, and they can only make small skateboards but not ladle skateboards. Through the improvement of the process and the introduction of Al2O3 or spinel slide plate, the thermal shock resistance, peeling resistance and erosion resistance have been significantly improved, than aluminum zirconium carbon slide plate is more suitable for some special steel continuous casting.
Table for the adoption of powder, a total of 15-4 - ingredients - organic binder - mixing - 1000 t press molding to 1650 ~ 1680 ℃ high temperature firing, Baptist oil, vacuum heat treatment and grinding process of alkaline skateboard performance index, used in 160 t converter ladle batch, 1560 ~ 1580 ℃ rimming steel, low alloy steel, half killed steel, life is 2 times, every time cast hole corrosion damage of 3 mm, uniform reaming, mild drought.

Table 15-5 compares the performance indexes of al2o3-mgo-c alkaline slide developed by using corundum aggregate to partially replace electrofused magnesia aggregate. MG is a magnesium carbonaceous slide plate, which can only be used for medium bag; AMG skateboard overcomes the disadvantage of poor thermal shock resistance of alkaline skateboard and can be successfully used as ladle skateboard.

Table 15-6 summarizes the performance indexes of three types of skateboards suitable for pouring high corrosion steel. PL1 and PL6 are based on the common aluminum carbon skateboards, which reduce the carbon content and/or silicon content, add aluminum metal, and heat treatment below 1000℃. The oxidation resistance and crack propagation resistance of these skateboards are improved. Spinel-c slide has the ability to resist the erosion of high calcium steel; ZrO2 Mosaic slide made by controlling appropriate particle size composition, proportion of monocline and cubic phase, adding appropriate amount of Cr2O3 has good corrosion resistance to high oxygen and high calcium steel. Table 15-7 compares the results of application and use times of casting calcium-treated steel for several sliding plates of different materials.