T91钢热浸镀铝及其在水蒸汽中的循环氧化行为
来源期刊：中南大学学报(自然科学版)2009年第4期
论文作者：张都清 刘光明 赵国群 管延锦
文章页码：956 - 962
关键词：T91钢；热浸镀铝；水蒸汽；循环氧化
Key words：T91 steel; hot dip aluminizing; water vapor; cyclic oxidation
摘 要：研究SA213T91钢热浸镀铝后并退火后样品在90% Ar+10% H2O气氛中于600，650和700 ℃下的循环氧化行为。研究结果表明：T91钢热浸镀铝并退火后样品在表面形成Fe2Al5金属间化合物层，该层中有贯穿Fe2Al5层的裂纹；Fe2Al5层下为扩散层；镀层表现良好的抗氧化性能；在600 ℃氧化速率缓慢，样品表面仅生成极薄的Al2O3膜，其生长方式主要由Al向外扩散为主，而在650 ℃和700 ℃时氧化质量增量增大；在循环氧化过程中，由于基体和镀层的热膨胀系数不匹配，镀层在降温和升温过程中将受到循环应力作用，镀层中裂纹增加，并导致镀层剥落。
Abstract: An aluminide coating was prepared on SA213T91 steel by hot dip aluminizing then annealing. The cyclic oxidation behaviors of coated samples were studied in 10% H2O＋90% Ar at 600, 650 and 700 ℃ for various time. The results show that Fe2Al5 intermetallic layer with penetrated micro-cracks forms on the sample surface after hot dip aluminizing and annealing. A diffusion layer containing Al is observed beneath the outer coating layer. The coated samples exhibit much better, oxidation resistance than that of bare sample oxidized under the same conditions. When the samples is oxidized at 600 ℃, the oxidation rate is very slow and only thin Al2O3 film forms on the sample surface. AFM observation reveals that the growth of oxide is dominated by Al diffusion outward. However, the oxidation rate is accelerated at 600 ℃ and 700 ℃. Because of the mismatch of linear expansion coefficient of coating and substrate, the stress was generated in the coating during the cyclic oxidation, which leads to more micro-cracks formation in the coating and parts of coating spallation.
基金信息：华电国际重点基金资助项目
