镁碳质塞棒棒头抗热震性优化及工业应用

浇铸钙处理钢时，铝碳质或尖晶石-碳质塞棒棒头容易被钢水中的游离Ca]侵蚀，而使用镁碳质材料能降低Ca]的侵蚀作用，进而提高棒头的使用寿命。研究了SiC细粉添加量对镁碳质棒头材料性能的影响，设计了镁碳质棒头复合结构并测试了产品的抗热震性，同时对比了镁碳质棒头与尖晶石-碳质棒头材料的常规性能和钢厂测试结果。研究结果表明，随着SiC细粉添加量的增多，材料常温强度和高温强度增大，而线膨胀系数下降。复合结构改善了棒头与棒身材料之间的物理匹配，提高了棒头稳定性，具体表现为镁碳质棒头试验样品经1 100℃热震循环3次后表面及内部均无裂纹。镁碳质棒头材料的力学强度虽稍弱于尖晶石-碳质棒头材料，但浇铸钙处理钢的表现更好。分析发现，导致尖晶石-碳质棒头材料损毁的直接原因是游离Ca]的侵蚀。

Optimization on thermal shock resistance and industrial applications of magnesia carbon stopper head

In the casting process of calcium-treated steel, alumina carbon stopper head and spinel carbon stopper head are easily corroded by the free Ca] in molten steel. Using magnesia carbon refractory can reduce the corrosion of Ca] and increase the service life of the stopper head. The influence of SiC powder amount on properties of magnesia carbon stopper head was studied, the composite structure of magnesia carbon stopper head was designed and the thermal shock resistance of the product was tested. The conventional properties and steel mill test results of magnesia carbon stopper head and spinel carbon stopper head were compared. Research indicates that, with the increase of SiC powder amount, the strength of materials at room temperature and high temperature are increased, while the thermal expansion coefficient is decreased. The composite structure improves the physical matching between the stopper head and the stopper body and improves stability of stopper head. The specific performance is that magnesia carbon stopper head test sample has no cracks on the surface and inside after thermal shock cycles at 1 100 ℃ for 3 times. Although the mechanical strength of magnesia carbon stopper head is slightly weaker than spinel carbon stopper head, the performance of casting calcium-treated steel for the former is better. The analysis finds that the direct cause of spinel carbon stopper head damage is the corrosion of free Ca].