含不同粒度SiC的MgO–Al2O3–C材料服役状态下的侵蚀机理

Degradation of MgO–Al_2O_3–C Refractories Containing SiC with Different Particle Sizes in Service State

采用精炼钢包对两种含不同粒度SiC的Mg O-Al_2O_3-C(MAC)材料在包壁部位进行了115~135炉的工业试验,发现SiC粒度显著影响MAC材料的侵蚀速率,采用平均粒径D50=24.58μm的SiC粉的MAC材料的侵蚀速率为1.05 mm/炉(135炉),采用平均粒径D50=4.34μm的SiC粉的MAC材料侵蚀速率为1.30 mm/炉(115炉)。对用后MAC材料的损毁机理研究表明:2种材料中SiC都与CO(g)反应生成SiO(g),一部分SiO(g)继续与CO(g)反应生成SiO_2(s)和C(s),利用体积膨胀促进了材料结构致密化,大幅提高了抗氧化性能;而另一部分SiO(g)直接溢出MAC材料。当SiC粒度较大时,SiC与CO(g)反应较慢,减少了SiO(g)直接溢出,生成更多SiO_2(s),使得组织结构更致密,抑制了MAC材料中C的氧化,材料组成与结构保持更加完好,强度较高,具有更高的抗钢水冲刷磨损能力;SiC粒度大,在提高材料抗氧化能力的同时,也减少了材料与熔渣的接触面积,降低了MgO向熔渣的溶解速率。故在精炼钢包环境中,平均粒径D50=24.58μm的SiC比D50=4.34μm的SiC更利于提高MAC材料的抗侵蚀能力。

Two kinds of Mg O–Al2O3–C（MAC） refractories containing SiC with different particle sizes were examined in the sidewall of refining ladle for 115–135 heats. The results show that the corrosion rate of the MAC refractories is remarkably affected by the particle size of SiC. The corrosion rate of the MAC refractory containing SiC with the median size（i.e., D（50）=24.58 μm） is 1.05 mm/heat（135 heats）, and that of MAC refractory containing SiC with the median size（i.e., D50=4.34 μm） is 1.30 mm/heat（115 heats）. It is indicated that SiC in the two refractories reacts with CO（g） to form SiO（g）, and part of SiO（g） further reacts with CO（g） to form SiO2（s） and C（s）, thus improving the oxidation resistance by densifying the structure because of the volume expansion. The reaction rate of SiC and CO（g） is slower when particle size of SiC is larger, leading to the decrease of the overflow rate of SiO（g） and the production of more SiO2（s）, which can densify the structure and inhibit the oxidation of carbon in MAC refractories. The more stable composition and structure of the material is, the higher strength and the better abrasion resistance will be. Furthermore, the larger particle size of SiC decreases the contact area between the slag and the material, and then decreases the dissolution rate of Mg O into slag. Therefore, the the MAC refractories containing SiC with the median size（i.e., D50=24.58 μm） have a higher corrosion resistance, compared to the MAC refractories containing SiC with the median size（i.e., D50=4.34 μm）.