摘要
目的使用超音速火焰喷涂(HVOF)方法制备Al-Cu-Fe准晶涂层,研究热处理温度对涂层中准晶相含量和性能的影响以及封孔处理对涂层耐蚀性的改善。方法以304不锈钢为基体和真空雾化Al-Cu-Fe准晶粉末为热喷涂材料,采用超音速火焰喷涂方法制备准晶涂层,并进行550~700℃热处理。利用透射电镜、扫描电镜、光学显微镜、能谱分析仪和X射线衍射仪分析准晶粉末和涂层的衍射花样、微观形貌、成分和相结构。分别使用显微硬度仪和电化学工作站对比测量304不锈钢和准晶涂层的硬度和耐蚀性能。结果粉末中二十面体准晶相(I相)为主相,并伴生准晶类似相(β相)。经过超音速火焰喷涂后,涂层中I相和β相的含量分别为78.7%和21.3%,相组成与原始粉末接近。550℃和600℃热处理1h后,涂层中β相消失,I相占比进一步上升,并伴随Al2Cu(θ相)产生。随着热处理温度继续升高至650℃,β相开始重新析出;当热处理温度升至700℃,β相占比增至13.5%。热处理后准晶涂层的最高硬度为674HV,为304不锈钢硬度(182HV)的3.7倍。准晶涂层经过热处理和表面封孔后,其在3.5%NaCl溶液中腐蚀的速率低于304不锈钢。结论合适的热处理温度是制备高纯准晶涂层的关键因素,准晶含量的提升有利于提高准晶涂层的硬度和耐蚀性。
Quasi-crystals,being brittle and porous in bulk form,are usually prepared as coatings,especially using thermal spraying for practical applications.However,due to the strict requirements for the formation of quasi-crystalline phases,powder composition,oxidization,spraying parameter,and heat treatment condition are all involved,which makes the preparation of high purity quasi-crystalline coatings quite difficult.Among the many thermal spraying techniques,high-velocity oxy-fuel spraying(HVOF)should be a good choice for such a purpose as it has a low heat-source temperature and a high particle projection speed,which can effectively avoid the oxidation of quasi-crystalline particles,reduce the ablation of the component metals of quasi-crystalline alloys,and improve the compactness and bonding strength of the coatings.In this article,high purity quasi-crystalline coatings are prepared using HVOF process.Besides the spraying process,heat treatments are specially focused to unveil the effects of different post-annealings on the content of quasi-crystalline phase,microstructure,hardness,and corrosion resistance of the prepared coatings.The chemical composition Al63Cu25Fe12of the icosahedral quascrystal in Al-Cu-Fe system is first selected according to the cluster-plus-glue-atom model and the electron-per-atom ratio(e/a),e/a=1.86.The pure Al,Cu and Fe metals are then melted into ingots in a vacuum induction furnace and the ingots are further atomized to make powders with particle size in the range of 15-50μm,the average particle size with high sphericity is 25μm.Lijia HV-8000 HVOF system is adopted to prepare quasi-crystalline coatings.The spraying parameters are as follows:the speed of spray gun is 300 mm/s,the spraying distance is 300 mm,the flow rate of aviation kerosene is 19 L/h,the flow rate of oxygen is 1850 scfh(1 scfh=28.3 L/h),and the powder feed rate is 30-35 g/min.The as-deposited coatings are finally annealed at 550-700℃for 1 hour in argon atmosphere.The surface of annealed sample is immersed in the sealin
作者
万鹏
曹达华
周瑜杰
杨玲
辛先峰
董闯
WAN Peng;CAO Da-hua;ZHOU Yu-jie;YANG Ling;XIN Xian-feng;DONG Chuang(Foshan Shunde Midea Electrical Heating Appliances Manufacturing Co.,Ltd.,Guangdong Foshan 528300,China;Dalian University of Technology,Liaoning Dalian 116024,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2023年第2期422-429,共8页
Surface Technology
基金
顺德区科技计划项目(201911220001)。
关键词
准晶涂层
超音速火焰喷涂
热处理
相组成
硬度
腐蚀
quasi-crystalline coating
high velocity oxy-fuel spraying
heat treatment
phase structure
hardness
corrosion