摘要
采用XRD、SEM、EDS、增重法测量和热力学计算等手段研究了铸态GH3625合金在900℃下不同腐蚀介质中(Air、75%Na_(2)SO_(4)+25%NaCl和2%SO_(2)+H_(2)O+Air)腐蚀120 h后的高温腐蚀行为,探讨了不同腐蚀介质下氧化膜的形成及破坏机制。研究表明,GH3625合金在不同介质中腐蚀后,从合金最表层到合金内部结构均可分为疏松氧化层、致密氧化层、贫Cr区和合金基体,其中氧化层主要由NiO、Cr_(2)O_(3)和NiCr_(2)O_(4)组成。同时,合金在熔盐和高温酸性气氛中腐蚀后的贫Cr区深度(约14和11μm)均大于在空气中氧化后贫Cr区深度(约8μm),腐蚀介质对合金表层氧化膜的破坏程度从大到小依次为熔盐介质、高温酸性气氛介质和空气介质。合金的腐蚀主要是不同介质下合金表层氧化膜的形成与溶解的相互竞争,当GH3625合金在熔盐介质中腐蚀时,腐蚀机制主要是氧化膜与Cl^(-)反应生成气相Cl_(2)和与Na_(2)O反应生成铬酸盐Na_(2)CrO_(4);而当GH3625合金在酸性气氛介质中腐蚀时,腐蚀机制主要是Cr、Ni元素与SO_(2)、O_(2)的连续硫化和氧化反应。
The corrosion behavior of as-cast GH3625 alloy were studied in different corrosive media(Air,75wt%Na_(2)SO_(4)+25wt%NaCl and 2%SO_(2)+H_(2)O+Air)at 900℃for 120 h,utilizing XRD,SEM,EDS,mass-gain measurement and thermodynamic calculation.The formation and destruction mechanism of the oxide film under different corrosive media were discussed.Results show that from the top layer to the internal structure of GH3625 alloy is divided into loose oxide layer,dense oxide layer,Cr poor zone and alloy matrix after corrosion in different media,and the oxide layer is mainly composed of NiO,Cr_(2)O_(3)and NiCr_(2)O_(4).In addition,the depth of Cr-poor zone after corrosion in corrosive medium(14μm and 11μm)is greater than that after oxidation in air(8μm).The damage degree of corrosion medium to the surface oxide film of the alloy is molten salt medium,acidic atmosphere medium and air medium in descending order.The corrosion of GH3625 alloy is mainly due to the competition between the formation and dissolution of the surface oxide film in different media.When GH3625 alloy is corroded in 75wt%Na_(2)SO_(4)+25wt%NaCl medium,the corrosion mechanism is mainly that the oxide film reacts with Cl^(-) to form gas phase Cl_(2)and reacts with Na_(2)O to form chromate Na_(2)CrO_(4).However,when GH3625 alloy is corroded in 2%SO_(2)+H_(2)O+Air,the corrosion mechanism is mainly the continuous sulfurization and oxidation reaction of Cr,Ni and SO_(2),O_(2).
作者
马元俊
丁雨田
刘建军
高钰璧
陈建军
王兴茂
Ma Yuanjun;Ding Yutain;Liu Jianjun;Gao Yubi;Chen Jianjun;Wang Xingmao(State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals,Lanzhou University of Technology,Lanzhou 730050,China;School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2022年第5期1713-1723,共11页
Rare Metal Materials and Engineering
基金
国家重点研发计划(2017YFA0700703)
国家自然科学基金(51661019)
甘肃省科技重大专项(145RTSA004)
兰州理工大学红柳一流学科建设计划。
关键词
GH3625合金
高温腐蚀
腐蚀介质
氧化膜
腐蚀机制
GH3625 alloy
high temperature corrosion
corrosive medium
oxide film
corrosion mechanism
