赤泥掺杂的涂料提高钢坯表面高温抗氧化性机理研究

Study on Mechanism of Red Mud Doped Coatings for Improving High Temperature Anti-Oxidation on Surface of Billet

以赤泥、SiO_(2)、MgO和石墨粉为主要原料,通过湿磨制备了赤泥掺杂涂料。对涂层在钢坯表面的脱落性能、抗氧化性能及机理进行分析,利用SEM-EDX、XRD、TG-DSC分析涂层的显微结构、物相组成、热重性能。结果表明:涂料的脱落性能明显好于市售涂料;涂料能够显著提高钢坯的高温抗氧化性能,有涂层的钢坯在900℃时的单位面积抗氧化烧损效果最佳,可降低80.5%;钢坯加热过程中涂层中石墨粉与O_(2)反应生成CO和CO_(2)混合气体层,阻挡外界O_(2)入侵,减缓钢坯的氧化速率;950℃时,原位生成的MgFe_(2)O_(4)尖晶石增强了涂层致密性,减缓了钢坯的氧化速率。

Red mud-doped coating was prepared by wet grinding with red mud,in which taking SiO_(2),Mg O and graphite powders as main raw materials.The peeling performance,anti-oxidation ability and mechanism of the coating on the surface of billets were analyzed.The microstructure,phase compositions and thermogravimetric properties of the coating were analyzed by SEM-EDX,XRD and TG-DSC.The results indicate that the peeling property of the coating is better than that of the commercial coatings.The coating can significantly improve the anti-oxidation performance of billets at high temperature.The anti-oxidation loss per unit area of coated billet at 900℃is the best,which can be reduced 80.5%.In the process of heating the billet,the graphite powder in the coating reacts with O_(2)to form a mixed gas layer of CO and CO_(2),which prevents the invasion of external O_(2)and slows down the oxidation rate of the billet.At 950℃,the Mg Fe_(2)O_(4)spinel which in-situ formed can enhance the compactness of the coating and slow down the oxidation rate of the billet.