火电机组过/再热器锅炉管内壁铝化物涂层研究(Ⅰ):涂层制备及组织结构  

Slurry Aluminide Coatings on Boiler Tubes for Overheater/Reheater(I):Preparation and Microstructure

作　　者：黄锦阳[1] 鲁金涛[1] 张醒兴 杨珍[1] 谷月峰[1] HUANG Jin-yang;LU Jin-tao;ZHANG Xing-xing;YANG Zhen;GU Yue-feng(National Engineering Research Center of Clean Coal Combustion for Utility Boilers,Xi’an Thermal Power Research Institute Co.Ltd,Xi’an 710032,China;Xi’an Yitong Thermal Power Technology Service Co.Ltd,Xi’an 710032,China)

机构地区：[1]西安热工研究院有限公司电站锅炉煤清洁燃烧国家工程中心,西安710032 [2]西安益通热工技术服务有限责任公司,西安710032

出　　处：《表面技术》2020年第7期272-279,共8页Surface Technology

基　　金：陕西省自然科学基础研究计划资助项目(2020JM-716);中国华能集团有限公司科技项目(HNKJ20-H43);陕西省特支计划青年拔尖项目(ZD18SST05)。

摘　　要：目的在奥氏体不锈钢锅炉管内壁制备抗高温蒸汽氧化涂层。方法采用料浆法在锅炉过/再热器用小口径Super304H不锈钢锅炉管内壁制备铝化物涂层,研究了钢管热处理制度范围内制备工艺(时间、温度)对涂层结构、成分和相组成的影响规律,同时基于扩散定律建立了涂层结构的预测模型。结果铝化物涂层厚度约为30~150μm,与基体冶金结合良好。涂层为双层结构,外层由(Fe,Ni)Al(Cr)相、Cr_xSi_y相以及少量Fe_3Al相组成,互扩散层(IDZ)由(Fe,Ni)Al相、Cr_xSi_y相、点状M_6C碳化物相和针状TCP相组成。涂层的制备温度和保温时间对互扩散层厚度变化影响显著,其随时间和温度的变化曲线近似满足抛物线规律。管材热处理制度范围内的温度过高,易减小涂层外层厚度。结论在匹配Super304H锅炉管热处理工艺的基础上,采用料浆法在小口径Super304H锅炉管内壁获得了双层结构的铝化物涂层。基于Fick第二扩散定律建立了涂层结构控制的预测模型,拟合结果与实验实测数据吻合较好,可为获得不同结构的涂层提供参考。The work aims to prepare the high-temperature resistant steam oxidation coating on the inner surface of austenitic stainless steel boiler tube.Al-Si slurry deposition process was employed to prepare aluminide coatings on the inner surface of Super304H boiler tubes used on overheater and reheater.The effects of process parameters(time and temperature)on the structure,composition,phase composition and atomic diffusion of the coatings were studied within the scope of the heattreatment on steel tube.Meanwhile,a prediction model of coating microstructure was established based on the Fick’s diffusion law.The aluminide coating had a thickness of about 30~150μm and showed good metallurgical bonding properties with the substrate.The coating had a two-layer structure,with an outer layer of(Fe,Ni)Al(Cr)phase,CrxSiy phases and a little Fe3Al and IDZ of(Fe,Ni)Al phase,CrxSiy phase,spotted M6C phase and needle-like TCP phase.The thickness of IDZ was significantly affected by the temperature and holding time.The thickness variation of this layer followed parabolic law with the holding time and the temperature.Besides,an excessive temperature within the heat treatment regime of tubes could easily reduce the thickness of outer layer.Aluminized coatings are successfully prepared on the inner surface of Super304H austenitic stainless steel boiler tube depending Al-Si slurry deposition process on the basis of matching Super304H boiler tube heat treatment process.A prediction model of coating microstructure control is established based on the Fick's second diffusion law.The prediction results are in good accordance with the experimentation results and can provide a reference for preparing the coatings with different microstructures.

关 键 词：锅炉管 SUPER304H 铝化物涂层 料浆法 扩散 工艺参数 

分 类 号：TG174.4[金属学及工艺—金属表面处理]