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采用热浸镀铝及随后的高温扩散处理在15CrMo钢表面制备热浸镀铝镀层。对热浸镀铝15CrMo钢和未处理15CrMo钢进行等温氧化测试。结果表明,通过热浸镀工艺获得了包含FeAl和Fe_3Al两相的镀层,镀层内存在Kirkendall孔洞和碳化物聚集区。相比较未处理15CrMo钢而言,热浸镀铝15CrMo钢具有优异的耐氧化抗性。热浸镀铝15CrMo钢的氧化增重曲线在650、850℃下缓慢升高;在850℃,未处理的15CrMo钢具有较差的耐氧化性,其氧化增量曲线随氧化时间延长而线性升高。在热氧化过程中,优先形成于铝化钢表面的Al_2O_3可作为屏障而阻碍氧进入镀层,而在裂纹周边形成的Fe_2O_3对镀层没有保护作用。
Hot-dip aluminized coatings were prepared on 15CrMo steel by hot-dip aluminizing followed by high-temperature diffusion. Isothermal oxidation tests were performed on hot dip aluminized 15CrMo steel and untreated 15CrMo steel. The results show that the coating containing two phases of FeAl and Fe_3Al is obtained by hot dip coating, and the Kirkendall holes and the carbide agglomeration zone exist in the coating. Hot dip aluminized 15CrMo steels have excellent resistance to oxidation compared to untreated 15CrMo steels. Oxidation weight gain curve of hot-dip aluminized 15CrMo steel increased slowly at 650 and 850 ℃, and untreated 15CrMo steel had poor oxidation resistance at 850 ℃. The oxidation increase curve increased linearly with the oxidation time high. During the thermal oxidation process, Al_2O_3 preferentially formed on the surface of aluminized steel can be used as a barrier to prevent oxygen from entering the coating, whereas Fe_2O_3 formed on the periphery of the crack has no protective effect on the coating.