Contact (galvanic) corrosion 关于接触腐蚀

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1、GeneralMetalFinishingContact(galvanic)corrosion关于接触腐蚀G.Krolik–GuangzhouChina–2015/12/11Whatiscontactcorrosion?什么是接触腐蚀?ProprietaryandConfidentialGeneralMetalFinishingContactcorrosionWhatiscontactCorrosion?Differentmetalsshowdifferentchemicalbehavior不同金属有不同的化学特性‒Relatedtoenvironment

2、alconditions与周围环境有关系Typeofelectrolytewhichsurroundthemetal金属周围的电解液Ioncontent离子的含量pHOxigencontent氧气含量Temperature温度etc.其它...Tocomparethemetalstheelectrochemicalpotentialcanbemeasuredunderdifferentconditions在不同条件下,金属间的电位差可以通过测量并比较Ifthedifferenceinthepotentialis>100mVcontactcor

3、rosionisprobable当不同金属间的电位差>100mV时很有可能发生接触腐蚀ProprietaryandConfidential3G.Krolik-GuangzhouChina-2015/12/11ContactcorrosionWhatiscontactCorrosion?Iftwoormoreelectricalconencteddifferentmetalsaredippedinanelectrolyte,electronswillflowfromthelessnoblemetalltothenobelmetal.当两种或两种以上通电的金属

4、浸泡在电解液中,电子从活性较强的金属流向相对惰性的金属Thelessnoblemetalbecometheanode–willbedisolved活性较强的金属这时做阳极-被溶解Onthenobelmetalforexamplegaswillbegenerated惰性金属上会有副产物生成，如:气体e(+)(-)Me+1H2lessnoblenobleProprietaryandConfidential4G.Krolik-GuangzhouChina-2015/12/11ContactcorrosionWhatiscontactCorrosion?Con

5、tactcorrosion-Oildistributionpipeinhumidenvironment接触腐蚀-如在潮湿环境中的油管-Contactofmaterialswithdifferentelectrochemicalpotential化学电位各不相同的金属接触Brass黄铜Aluminium铝UnalloyedSteel非合金钢Copper铜ProprietaryandConfidential5G.Krolik-GuangzhouChina-2015/12/11Electrochemicalpotential电位差ProprietaryandCon

6、fidentialGeneralMetalFinishingContactcorrosionElectrochemicalpotential–Standardpotential电位差–标准电势Thestandartpotentialismeasuredunderstandartconditions标准电势需要在特定标准条件下测试。‒Ionactivity1(1mol/l)离子活性1‒Temperature温度25°C‒Barometricpressure气压101,325kPa‒ph=0Referenceelectrodestandardhydrogen

7、electrode参考电极为标准氢电极ProprietaryandConfidential7G.Krolik-GuangzhouChina-2015/12/11ContactcorrosionElectrochemicalpotential–StandardpotentialMeasuringequipment测量设备Ionconcentrationofmetalion金属离子浓度p=101,325kPa1mol/le.g.Ag+StandardhydrogenMetal金属e.g.silverelectrode(Ag)标准氢电极pH=0Proprieta

8、ryandConfidential8G.Krolik