Abstract:

Al-Si-Cr coating was prepared on the surface of 25Cr35NiNb alloy by pack cementation, and its anti-coking properties were studied by coking experiment using ethylene cracking test apparatus. The microstructure of coating and the morphology of coke were investigated with metallurgic microscope, electronic scanning microscope (SEM) and energy dispersive X-ray spectrometer (EDS). Al-Si-Cr coating with thickness of about 130 mm was obtained by pack cementation. The coating had multiple layers with dense structure, consisting of an outer layer composed of aluminum-silicon-rich compounds and an inner layer composed of chromium- silicon-rich compounds. The Al-Si-Cr coating had excellent coking inhibiting properties. It could inhibit catalytic coking effectively, and the rate of coke inhibition was up to 72.5%.

Key words: ethylene cracking, coking, coking inhibition, coating, pack cementation

摘要：

采用固体粉末包埋渗方法在25Cr35NiNb合金表面制备Al-Si-Cr涂层,通过乙烯裂解模拟装置中的结焦实验,对涂层抑制结焦性能进行分析评价。运用金相显微镜、扫描电子显微镜(SEM)和能谱仪(EDS)等方法分析了涂层显微组织及结焦层形貌特征。结果表明,采用粉末包埋共渗可以得到厚度在130 mm左右的Al-Si-Cr涂层,涂层具有多层结构且组织致密,外层为富铝硅层,内层为富铬硅层;Al-Si-Cr涂层具有良好的抗结焦性能,可有效抑制催化结焦,抑制结焦率达72.5%。

关键词: 乙烯裂解, 焦化, 抑制结焦, 涂层, 包埋渗