摘要
采用光学显微镜、扫描电镜、电子探针、X射线衍射、XPS等方法对银质纪念币在大气中放置出现的白斑的成份、结构进行了宏观和微观的分析检查,并结合湿热加速试验及银币生产现场情况,综合分析白斑的生成机理.结果表明:在湿润环境中,Cl^-、O_2、H_2S是导致银币表面产生白斑的主要物质;银币表面白斑腐蚀产物主要由AgCl、Ag_2O和Ag_2S构成,腐蚀产物的颜色并不随腐蚀白斑长大而改变;银币表面存在的供氧差异腐蚀电池是银币表面白斑形核、长大的主要诱因.
Morphology and chemical composition of the corrosion spots on the surface of souvenir silver coins were examined by optical microscope（OM）,scanning electron microscope（SEM）,electron microprobe（EMPA）,X- ray photoelectron spectroscopy（XPS）,and X-ray diffraction（XRD）. It was found that the silver was sensitive to the presence of Cl^-、O_2 and H_2S in humid atmosphere. XPS and XRD analytical results showed that the white spots were consisted of AgCl、Ag_2O and Ag_2S.The white tarnished complex on the surface of silver was a series of electrochemical process that required the presence of chloride,oxygen and sulfur.
出处
《腐蚀科学与防护技术》
CAS
CSCD
北大核心
2011年第2期186-190,共5页
Corrosion Science and Protection Technology
关键词
银纪念币
白斑
AGCL
Ag_2O
Ag_2S
电化学腐蚀
silver coins
white spot
silver chloride
silver oxide
silver sulfide
electrochemical corrosion
