渗铝涂层对Cr20Ni80电热合金丝抗氧化性能的影响  

Study on the Oxidation Resistance of Cr20Ni80 Electrothermal Alloy Wire by Aluminized Coating

作　　者：王晓军[1] 王馨 WANG Xiao-jun;WANG Xin(College of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050)

机构地区：[1]兰州理工大学材料科学与工程学院,甘肃兰州730050

出　　处：《材料保护》2021年第1期1-6,共6页Materials Protection

摘　　要：为提高电热合金丝的抗高温氧化性能,采用固体粉末包埋法在Cr20Ni80电热合金丝表面制备渗铝涂层,通过高电阻电热合金快速寿命装置对渗铝试样在恒温1 000℃下进行高温氧化试验、在恒温1 200℃下进行快速寿命测试并拟合电阻随时间的变化曲线,利用X射线衍射仪(XRD)、扫描电镜(SEM)、能谱分析(EDS)和热重分析仪(TGA)研究了渗铝涂层结构、氧化膜形貌、氧化膜相组成以及渗铝试样氧化动力学。结果表明:渗铝试样快速寿命相较于未渗铝试样提高了7.62%。渗铝涂层为双层结构,内外层厚度约为5μm和40μm。渗铝试样氧化动力学曲线基本符合抛物线规律。氧化膜分为3层:最外层为Al2O3与微量NiO;次外层为Ni Al及少量Al2O3、NiO;最内层是富Cr层和Cr2O3,并存在少量不连续分布的Si O2。氧化初期,渗铝试样迅速在表面形成了一层均匀致密的Al2O3保护性氧化膜,有效地改善了Cr20Ni80电热合金丝抗氧化性能。In order to improve the high-temperature oxidation resistance of electrothermal alloy wire,an aluminized coating was prepared on the surface of Cr20 Ni80 electrothermal alloy wire by solid powder embedding. The high-temperature oxidation test of aluminized sample was carried out at 1 000 ℃ in air by a high resistance heating electrothermal alloy fast life device,and the fast life test was performed at a constant temperature of 1 200 ℃ with fitting the resistance curve with time. In addition,X-ray diffraction( XRD),scanning electron microscope( SEM),energy spectrum analysis( EDS) and thermogravimetric analyzer( TGA) were used to study the structure of aluminized coating,the morphology and phase composition of oxide films and the oxidation kinetics of aluminized sample. Results showed that the fast life of aluminized samples increased by 7.62% compared with that of unaluminized samples. The aluminized coating possessed a two-layer structure with 5 μm thickness of the inner layer and 40 μm thickness of the outer layer. Meanwhile,the oxidation kinetics curve of the aluminized sample basically conformed to the parabolic law. The oxide film could be divided into three layers: the outermost layer was Al2 O3 and trace Ni O;the secondary outer layer was Ni Al and a small amount of Al2 O3 and Ni O;the innermost layer was Cr-rich layer,Cr2 O3 and a small amount of Si O2 with discontinuous distribution. At the initial stage of oxidation,an uniform and dense Al2 O3 protective oxide film was formed quickly on the surface of aluminized sample,so that the oxidation resistance of Cr20 Ni80 electrothermal alloy wire was effectively improved.

关 键 词：Cr20Ni80电热合金 固体粉末包埋法 渗Al涂层 高温氧化 

分 类 号：TG174.44[金属学及工艺—金属表面处理]