摘要
目的研究S30432涂覆信源和榆能电厂两种不同硫酸盐含量的煤灰后的腐蚀行为,探讨S30432在SO2气氛/煤灰环境中的高温腐蚀机制。方法将涂覆煤灰的S30432钢试样置于烟气/煤灰中腐蚀,间隔一定时间取出样品称量,获得腐蚀动力学曲线。采用扫描电子显微镜、能谱分析仪和X-射线衍射仪等,研究腐蚀产物的形貌、成分和物相组成。结果合金发生了氧化和硫化腐蚀,腐蚀过程中有加速腐蚀阶段。S30432在低硫含量煤灰腐蚀后未见明显的腐蚀产物剥落,试样表面生成相对致密且具有保护性作用的Cr_2O_3膜,腐蚀产物膜较薄。在高硫含量煤灰中,腐蚀产物分层生长且剥落严重,腐蚀2000 h后失重超过45 mg/cm^2,腐蚀产物层主要由Fe2O3、(Fe,Cr)_2O_3、NiCr_2O_4及嵌入腐蚀层的煤灰粒子组成。在腐蚀层/基体界面形成了富Cr和S的腐蚀层。结论 S30432在烟气/信源煤灰环境中比在烟气/榆能煤灰环境中更耐蚀。煤灰中硫酸盐含量增加,S30432的腐蚀速率显著增加。在高温烟气/煤灰协同作用下,合金易发生热腐蚀,铁、镍、铬及其氧化物在合金表面熔盐中的溶解是造成合金耐蚀性降低的原因。
The work aims to study high temperature corrosion behavior of S30432 austenitic stainless steel coated with coal-ash received from Xinyuan and Yulin power plants in 0.3%SO2 flue gas at 700℃.Corrosion tests were conducted by placing S30432 steel coated with coal-ash in fuel gas/coal ash.Mass change was obtained by weighting the samples at intervals during the test,and corrosion kinetics of the samples was plotted.Morphology,constituents and phase composition of the corrosion products were investigated by SEM,EDS and XRD.The S30432 steel undergone oxidation,sulfidation corrosion.The accelerated corrosion stage was observed during the corrosion test.After S30432 corroded in the coal ash with low sulfur content,no obvious corrosion product spallation was observed,a relatively compact and protective Cr2O3 film was formed on the surface of the samples,and corrosion product film was thinner.However,the corrosion products grew in layer and peeled off severely in the coal ash with high sulphur content,weight loss exceeded 45 mg/cm^2 after 2000 h.The layer of corrosion products was mainly composed of Fe2O3,(Fe,Cr)2O3,NiCr2O4 and coal ash particles embedded in the corrosion layer.Cr and S-enriched corrosion layer was formed on the corrosion layer/substrate interface.Corrosion resistance of S30432 steel in flue-gas/Xinyuan coal-ash is much better than that of S30432 in flue-gas/Yuneng coal-ash.Corrosion rate of S30432 increases significantly with the increase of sulfate content in coal ash.Alloy is susceptible to hot corrosion under the synergistic effect of high temperature flue gas/coal ash.Rapid degradation of corrosion resistance of alloy is attributed to dissolution of iron,nickel,chromium and their oxides in molten salt on the surface and alloy.
作者
张民强
黄丽琴
刘光明
刘宇钢
汪元奎
毛晓飞
ZHANG Min-qiang;HUANG Li-qin;LIU Guang-ming;LIU Yu-gang;WANG Yuan-kui;MAO Xiao-fei(Dongfang Boiler Group Co.,Ltd,Material Research Institute,Zigong 643001,China;School of Materials Science and Engineering,Nanchang Hangkong University,Nanchang 330063,China;Guodian Science and Technology Research Institute,Wuhan 430066,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2018年第8期251-256,共6页
Surface Technology
关键词
S30432
煤灰
模拟烟气
高温腐蚀
硫酸盐
剥落
S30432
coal ash
simulated fuel gas
high temperature corrosion,sulfate
spallation
