铝碳质长水口用低铝抗氧化涂层的研制

Study on Low Alumina Anti-Oxidation Coatings for Aluminum-Carbon Long Nozzle

为抑制铝碳质长水口使用过程中石墨的氧化,其表面会涂覆含20%~30%Al_2O_3的抗氧化涂层,但切割丝钢等特种钢冶炼过程必须严格控制钢液中夹杂的Al_2O_3的含量,因此需要制备低氧化铝含量的抗氧化涂层。本文通过调节涂料组成、加水量和水玻璃加入量制备了低铝抗氧化涂层,并利用扫描电镜分析了抗氧化实验后试样断口的显微结构。结果表明:以粘土粉、钾长石粉和硅砂为主要原料,添加10%硼砂的涂料可在800℃形成良好的釉层,此时涂料中Al_2O_3的含量可降至12%,得到了低铝涂料;当加入占涂料质量80%的水和40%的水玻璃时,涂层具有最佳的涂覆性能和抗氧化性能,涂层和长水口基体结合致密,保护了长水口中的石墨不被氧化。

The aluminum-carbon-based long nozzle is a functional original used in the steel smelting process.Due to the addition of graphite,the service life reduction of the long nozzle caused by the oxidation of graphite should be avoid.Generally,the surface of the long nozzle is coated with a layer containing 20%~30%Al2O3 anti-oxidation coatings to meet the requirement.However,during the smelting process of wire-cutting steel and other special steels,it is necessary to strictly control the content of Al2O3 in the molten steel.Therefore,it is requested to reduce the content of alumina in the anti-oxidation coatings applied to the surface of the long nozzle in the smelting process to prepare low alumina content of antioxidant coatings.This paper was focused on the preparation process of low alumina content coatings for aluminum-carbon long nozzle.Through the adjustment of the coatings composition and the amount of water and the water glass added.The microstructure of the fracture of the sample after anti-oxidation experiment was analyzed by using a scanning electron microscope,it is concluded that the coatings based on clay powder,potassium feldspar powder and silica sand as the main raw materials,with incorporation of 10%borax could form a good glaze layer at 800℃,while the content of Al2O3 reduced down to 12%,forming a low-alumina coatings;When added with 80%water and 40%water glass,the coatings showed the best application performance and anti-oxidation properties.The coatings and the long nozzle could be tightly adhered to protect the graphite in the long nozzle from oxidation.