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腐蝕電化學阻抗譜等效電路解析完備性研究

2020-12-03 01:29:33 hualin

摘要:


隨著使用(yong)電(dian)化學(xue)(xue)(xue)(xue)(xue)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)方(fang)法(fa)(fa)研(yan)(yan)究(jiu)(jiu)腐(fu)蝕(shi)(shi)過(guo)程的(de)(de)(de)工(gong)(gong)(gong)作日益增多,腐(fu)蝕(shi)(shi)電(dian)化學(xue)(xue)(xue)(xue)(xue)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)解(jie)(jie)析(xi)(xi)(xi)(xi)技術(shu)逐漸成為(wei)腐(fu)蝕(shi)(shi)科學(xue)(xue)(xue)(xue)(xue)家需(xu)要(yao)掌握(wo)的(de)(de)(de)重要(yao)研(yan)(yan)究(jiu)(jiu)工(gong)(gong)(gong)具(ju)之(zhi)一。近年(nian)來,電(dian)化學(xue)(xue)(xue)(xue)(xue)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)方(fang)法(fa)(fa)研(yan)(yan)究(jiu)(jiu)的(de)(de)(de)腐(fu)蝕(shi)(shi)體系越(yue)來越(yue)復(fu)雜(za),不僅腐(fu)蝕(shi)(shi)環境和金(jin)屬狀(zhuang)態復(fu)雜(za)化,且(qie)形(xing)成于金(jin)屬表面界面膜層(ceng)的(de)(de)(de)種(zhong)(zhong)類也越(yue)來越(yue)多,導致簡單電(dian)化學(xue)(xue)(xue)(xue)(xue)體系的(de)(de)(de)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)等(deng)效(xiao)(xiao)電(dian)路(lu)解(jie)(jie)析(xi)(xi)(xi)(xi)方(fang)法(fa)(fa)越(yue)來越(yue)難以(yi)滿足復(fu)雜(za)腐(fu)蝕(shi)(shi)體系解(jie)(jie)析(xi)(xi)(xi)(xi)建(jian)模(mo)(mo)的(de)(de)(de)要(yao)求。與動(dong)力學(xue)(xue)(xue)(xue)(xue)解(jie)(jie)析(xi)(xi)(xi)(xi)方(fang)法(fa)(fa)相比,模(mo)(mo)擬(ni)等(deng)效(xiao)(xiao)電(dian)路(lu)的(de)(de)(de)解(jie)(jie)析(xi)(xi)(xi)(xi)方(fang)法(fa)(fa)因(yin)其簡單直觀而易于理解(jie)(jie),應用(yong)范(fan)圍(wei)日益擴(kuo)展。但其固有的(de)(de)(de)解(jie)(jie)析(xi)(xi)(xi)(xi)過(guo)程不嚴謹(jin)、不規(gui)范(fan)等(deng)不足,導致腐(fu)蝕(shi)(shi)過(guo)程等(deng)效(xiao)(xiao)電(dian)路(lu)模(mo)(mo)型缺陷增加和學(xue)(xue)(xue)(xue)(xue)術(shu)價(jia)值下降(jiang)。為(wei)此,在多年(nian)研(yan)(yan)究(jiu)(jiu)腐(fu)蝕(shi)(shi)電(dian)化學(xue)(xue)(xue)(xue)(xue)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)等(deng)效(xiao)(xiao)電(dian)路(lu)解(jie)(jie)析(xi)(xi)(xi)(xi)方(fang)法(fa)(fa)的(de)(de)(de)基礎上,本(ben)文(wen)分析(xi)(xi)(xi)(xi)了(le)電(dian)化學(xue)(xue)(xue)(xue)(xue)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)等(deng)效(xiao)(xiao)電(dian)路(lu)解(jie)(jie)析(xi)(xi)(xi)(xi)方(fang)法(fa)(fa)在腐(fu)蝕(shi)(shi)研(yan)(yan)究(jiu)(jiu)中的(de)(de)(de)應用(yong)現(xian)狀(zhuang),探討了(le)等(deng)效(xiao)(xiao)電(dian)路(lu)方(fang)法(fa)(fa)解(jie)(jie)析(xi)(xi)(xi)(xi)腐(fu)蝕(shi)(shi)過(guo)程的(de)(de)(de)優點和不足,以(yi)及(ji)提(ti)高這(zhe)一解(jie)(jie)析(xi)(xi)(xi)(xi)方(fang)法(fa)(fa)學(xue)(xue)(xue)(xue)(xue)術(shu)價(jia)值的(de)(de)(de)必要(yao)性和可行(xing)途徑,以(yi)期建(jian)立嚴謹(jin)規(gui)范(fan)的(de)(de)(de)腐(fu)蝕(shi)(shi)電(dian)化學(xue)(xue)(xue)(xue)(xue)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)等(deng)效(xiao)(xiao)電(dian)路(lu)模(mo)(mo)型解(jie)(jie)析(xi)(xi)(xi)(xi)路(lu)線,以(yi)適應復(fu)雜(za)腐(fu)蝕(shi)(shi)過(guo)程的(de)(de)(de)模(mo)(mo)型化研(yan)(yan)究(jiu)(jiu)需(xu)求,為(wei)腐(fu)蝕(shi)(shi)科學(xue)(xue)(xue)(xue)(xue)工(gong)(gong)(gong)作者提(ti)供一種(zhong)(zhong)高效(xiao)(xiao)實(shi)用(yong)的(de)(de)(de)腐(fu)蝕(shi)(shi)電(dian)化學(xue)(xue)(xue)(xue)(xue)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)解(jie)(jie)析(xi)(xi)(xi)(xi)工(gong)(gong)(gong)具(ju)。


關(guan)鍵詞: 腐蝕過程 ; 電化學阻抗譜 ; 等效電路 ; 模型 ; 判據


三十多(duo)年(nian)前,電化學阻抗(kang)譜(pu)(pu) (EIS) 還是(shi)一種令人敬畏的“高大上”復(fu)雜(za)電化學技(ji)術(shu)(shu),但近年(nian)來使用(yong)(yong)這一方法(fa)的腐(fu)(fu)蝕(shi)研(yan)究論文越來越多(duo)。常見(jian)腐(fu)(fu)蝕(shi)期刊每期少則2篇(pian),多(duo)則5篇(pian)以(yi)上,已(yi)成為(wei)腐(fu)(fu)蝕(shi)研(yan)究的不(bu)(bu)可(ke)或缺的重要方法(fa)之(zhi)一。其原因(yin)不(bu)(bu)難理(li)解(jie),其一,EIS擾動(dong)小,響應(ying)寬(kuan),提供近原位(wei)豐(feng)富(fu)腐(fu)(fu)蝕(shi)過程(cheng)(cheng)宏觀和微觀信(xin)息(xi),有助于(yu)(yu)機(ji)(ji)理(li)分析(xi)和建模;其二,電化學阻抗(kang)譜(pu)(pu)測試(shi)儀器和阻抗(kang)譜(pu)(pu)擬合(he)技(ji)術(shu)(shu)快(kuai)速發展和普(pu)及(ji);其三,不(bu)(bu)僅可(ke)應(ying)用(yong)(yong)于(yu)(yu)各種類型(xing)腐(fu)(fu)蝕(shi)研(yan)究,而且可(ke)應(ying)用(yong)(yong)于(yu)(yu)工程(cheng)(cheng)中腐(fu)(fu)蝕(shi)監檢測和腐(fu)(fu)蝕(shi)控制。EIS獲得(de)過程(cheng)(cheng)機(ji)(ji)理(li)信(xin)息(xi)層次豐(feng)富(fu),有助于(yu)(yu)理(li)解(jie)過程(cheng)(cheng)機(ji)(ji)理(li)和建立腐(fu)(fu)蝕(shi)模型(xing),但是(shi)另一方面,多(duo)相多(duo)界面體(ti)(ti)系的復(fu)雜(za)腐(fu)(fu)蝕(shi)過程(cheng)(cheng)的EIS解(jie)析(xi)和建模難度增(zeng)加,致使經(jing)驗不(bu)(bu)足的腐(fu)(fu)蝕(shi)研(yan)究者不(bu)(bu)能(neng)科學合(he)理(li)應(ying)用(yong)(yong)這一工具。阻抗(kang)譜(pu)(pu)解(jie)析(xi)技(ji)術(shu)(shu)已(yi)成為(wei)復(fu)雜(za)腐(fu)(fu)蝕(shi)過程(cheng)(cheng)EIS研(yan)究方法(fa)中值(zhi)得(de)關注的瓶頸問題。


1 腐蝕EIS方法發(fa)展現狀


EIS方(fang)(fang)法來源于電(dian)(dian)(dian)(dian)(dian)(dian)工學(xue)(xue)(xue)中分(fen)析電(dian)(dian)(dian)(dian)(dian)(dian)路頻譜(pu)響應(ying)的(de)(de)(de)交流阻(zu)(zu)(zu)抗(kang)(kang)(kang)技(ji)術。上世紀50年代,電(dian)(dian)(dian)(dian)(dian)(dian)氣工程師Delahay首先(xian)提出用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)工學(xue)(xue)(xue)的(de)(de)(de)交流阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)方(fang)(fang)法研究電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)(hua)學(xue)(xue)(xue)動(dong)力學(xue)(xue)(xue)問題[1]。荷(he)蘭科學(xue)(xue)(xue)家(jia)(jia)Sluyters的(de)(de)(de)系統(tong)研究將其發展(zhan)為電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)(hua)學(xue)(xue)(xue)方(fang)(fang)法中重(zhong)要工具[2],而法國(guo)(guo)科學(xue)(xue)(xue)家(jia)(jia)Epelboin首先(xian)應(ying)用(yong)EIS研究腐(fu)蝕(shi)電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)(hua)學(xue)(xue)(xue)中的(de)(de)(de)陽極(ji)溶解動(dong)力學(xue)(xue)(xue),使其成為研究腐(fu)蝕(shi)問題的(de)(de)(de)重(zhong)要方(fang)(fang)法[3]。80年代第一屆國(guo)(guo)際電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)(hua)學(xue)(xue)(xue)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)學(xue)(xue)(xue)術會議決定在電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)(hua)學(xue)(xue)(xue)領(ling)域采(cai)用(yong)“電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)(hua)學(xue)(xue)(xue)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)”一詞取代“交流阻(zu)(zu)(zu)抗(kang)(kang)(kang)”推(tui)動(dong)了這(zhe)一方(fang)(fang)法在腐(fu)蝕(shi)領(ling)域中的(de)(de)(de)應(ying)用(yong),曹楚南系統(tong)研究了腐(fu)蝕(shi)電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)(hua)學(xue)(xue)(xue)領(ling)域中電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)(hua)學(xue)(xue)(xue)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)理(li)論和應(ying)用(yong)問題,他的(de)(de)(de)《電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)(hua)學(xue)(xue)(xue)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)導論》已經成為電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)(hua)學(xue)(xue)(xue)阻(zu)(zu)(zu)抗(kang)(kang)(kang)譜(pu)方(fang)(fang)法研究腐(fu)蝕(shi)電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)(hua)學(xue)(xue)(xue)行為規律的(de)(de)(de)重(zhong)要參考書[4]。


近年(nian)來具備快速(su)(su)(su)測(ce)量(liang)和(he)(he)(he)數據(ju)分(fen)析(xi)(xi)(xi)擬合功(gong)能(neng)的(de)(de)(de)電(dian)(dian)(dian)化學(xue)工(gong)作站的(de)(de)(de)快速(su)(su)(su)發(fa)展,推動了(le)腐(fu)(fu)蝕EIS測(ce)試技術的(de)(de)(de)普及應(ying)用,實現了(le)EIS全程自(zi)動測(ce)量(liang)和(he)(he)(he)等效電(dian)(dian)(dian)路參數擬合計算(suan)功(gong)能(neng)。材(cai)料和(he)(he)(he)工(gong)程領域的(de)(de)(de)腐(fu)(fu)蝕研究(jiu)日益增(zeng)(zeng)加(jia)(jia),腐(fu)(fu)蝕研究(jiu)隊伍快速(su)(su)(su)擴(kuo)張,體(ti)(ti)現在國內外腐(fu)(fu)蝕期刊(kan)中(zhong)使用EIS方(fang)法的(de)(de)(de)研究(jiu)論文顯著增(zeng)(zeng)加(jia)(jia)的(de)(de)(de)趨勢。與(yu)(yu)此同時,隨著簡單腐(fu)(fu)蝕體(ti)(ti)系(xi)解(jie)析(xi)(xi)(xi)方(fang)法的(de)(de)(de)成(cheng)熟,研究(jiu)的(de)(de)(de)腐(fu)(fu)蝕體(ti)(ti)系(xi)迅速(su)(su)(su)擴(kuo)展,體(ti)(ti)系(xi)和(he)(he)(he)過(guo)(guo)(guo)程的(de)(de)(de)復(fu)雜程度(du)也(ye)(ye)(ye)顯著增(zeng)(zeng)加(jia)(jia)。EIS方(fang)法不斷擴(kuo)展應(ying)用的(de)(de)(de)同時,面(mian)臨數據(ju)解(jie)析(xi)(xi)(xi)難度(du)也(ye)(ye)(ye)越來越大(da)。與(yu)(yu)此同時也(ye)(ye)(ye)看到,一(yi)些(xie)研究(jiu)者(zhe)在腐(fu)(fu)蝕過(guo)(guo)(guo)程EIS解(jie)析(xi)(xi)(xi)和(he)(he)(he)建模方(fang)面(mian)存在一(yi)些(xie)與(yu)(yu)日增(zeng)(zeng)加(jia)(jia)的(de)(de)(de)理解(jie)力不足。究(jiu)其原(yuan)(yuan)因在于EIS方(fang)法起源于電(dian)(dian)(dian)工(gong)學(xue),發(fa)展于電(dian)(dian)(dian)化學(xue),使用EIS技術的(de)(de)(de)腐(fu)(fu)蝕研究(jiu)者(zhe)不僅(jin)需要掌(zhang)(zhang)握腐(fu)(fu)蝕過(guo)(guo)(guo)程結構(gou)特征,掌(zhang)(zhang)握動力學(xue)分(fen)析(xi)(xi)(xi)技術,也(ye)(ye)(ye)需要具備一(yi)些(xie)電(dian)(dian)(dian)子電(dian)(dian)(dian)路和(he)(he)(he)電(dian)(dian)(dian)極(ji)過(guo)(guo)(guo)程基礎。如,電(dian)(dian)(dian)阻(zu)性、電(dian)(dian)(dian)容(rong)性和(he)(he)(he)電(dian)(dian)(dian)感性響應(ying)電(dian)(dian)(dian)流/電(dian)(dian)(dian)位(wei)特征,電(dian)(dian)(dian)流相(xiang)位(wei)滯(zhi)后(hou)和(he)(he)(he)超(chao)前意(yi)義,腐(fu)(fu)蝕過(guo)(guo)(guo)程中(zhong)電(dian)(dian)(dian)荷流動形式(shi),擴(kuo)散阻(zu)抗(kang)的(de)(de)(de)起因,負阻(zu)抗(kang)產生原(yuan)(yuan)因,電(dian)(dian)(dian)荷遷移電(dian)(dian)(dian)阻(zu)和(he)(he)(he)極(ji)化電(dian)(dian)(dian)阻(zu)差別,涂層(ceng)電(dian)(dian)(dian)容(rong)和(he)(he)(he)涂層(ceng)電(dian)(dian)(dian)阻(zu)的(de)(de)(de)關系(xi)等概念的(de)(de)(de)理解(jie)是解(jie)析(xi)(xi)(xi)阻(zu)抗(kang)響應(ying)不可或缺(que)的(de)(de)(de)。


2 腐蝕(shi)EIS方法構成(cheng)


EIS方法包含兩個部分(fen),EIS測量和EIS解析,二者缺一不可。


首先需(xu)要測(ce)量(liang)(liang)包含體系腐(fu)(fu)蝕(shi)過(guo)(guo)程(cheng)(cheng)可(ke)靠(kao)信(xin)息(xi)的(de)(de)EIS。電化(hua)學阻(zu)(zu)抗方法是靈敏度極高的(de)(de)交流方法,可(ke)以測(ce)定高達1010 Ω高阻(zu)(zu)抗體系的(de)(de)微弱響(xiang)(xiang)應(ying)信(xin)號,也(ye)容(rong)易受到環境和(he)(he)工(gong)頻電磁噪聲的(de)(de)干擾而發生畸(ji)變,影響(xiang)(xiang)數據解析的(de)(de)可(ke)靠(kao)性。此外,腐(fu)(fu)蝕(shi)過(guo)(guo)程(cheng)(cheng)通常由多(duo)個平行過(guo)(guo)程(cheng)(cheng)和(he)(he)連(lian)續過(guo)(guo)程(cheng)(cheng)組(zu)成,且主(zhu)(zhu)響(xiang)(xiang)應(ying)過(guo)(guo)程(cheng)(cheng)會隨進程(cheng)(cheng)演化(hua)而轉移(yi)。測(ce)量(liang)(liang)期(qi)間(jian)(jian)需(xu)要增強主(zhu)(zhu)響(xiang)(xiang)應(ying),減弱干擾信(xin)號,同時(shi)(shi)選擇合適的(de)(de)時(shi)(shi)機,在主(zhu)(zhu)響(xiang)(xiang)應(ying)腐(fu)(fu)蝕(shi)過(guo)(guo)程(cheng)(cheng)出現期(qi)間(jian)(jian)實施測(ce)量(liang)(liang),才能(neng)獲得目標(biao)過(guo)(guo)程(cheng)(cheng)的(de)(de)響(xiang)(xiang)應(ying)數據。如點蝕(shi)誘導(dao)期(qi)處于鈍化(hua)期(qi)和(he)(he)發展期(qi)之(zhi)間(jian)(jian)的(de)(de)點蝕(shi)萌生期(qi)間(jian)(jian),測(ce)定其電化(hua)學阻(zu)(zu)抗譜響(xiang)(xiang)應(ying)必須把握好(hao)測(ce)量(liang)(liang)時(shi)(shi)間(jian)(jian),既不能(neng)早(zao)也(ye)不能(neng)晚,才能(neng)測(ce)量(liang)(liang)到如圖(tu)1所(suo)示誘導(dao)期(qi)阻(zu)(zu)抗譜。


測(ce)(ce)量方(fang)法(fa)需根據(ju)系統響應(ying)的(de)(de)(de)(de)因果性、線性和穩定性要求合理設(she)計(ji),才(cai)能夠獲(huo)得(de)(de)(de)需要的(de)(de)(de)(de)結果。很多難于(yu)理解的(de)(de)(de)(de)阻抗譜響應(ying)并(bing)不是(shi)所關心(xin)腐(fu)(fu)蝕過程的(de)(de)(de)(de)響應(ying),而(er)是(shi)測(ce)(ce)量環節不當得(de)(de)(de)到的(de)(de)(de)(de)不具有解析價值的(de)(de)(de)(de)無關響應(ying)。研究(jiu)者不僅需要根據(ju)研究(jiu)內容設(she)計(ji)合理的(de)(de)(de)(de)測(ce)(ce)試方(fang)法(fa),還需要具備識別(bie)和修正反(fan)常阻抗譜響應(ying)的(de)(de)(de)(de)能力(li),從(cong)而(er)獲(huo)得(de)(de)(de)具有解析價值的(de)(de)(de)(de)腐(fu)(fu)蝕EIS數據(ju)。


EIS測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)和(he)(he)(he)解(jie)(jie)(jie)(jie)(jie)析(xi)兩(liang)者密(mi)切相關(guan)。解(jie)(jie)(jie)(jie)(jie)析(xi)結(jie)果(guo)質(zhi)(zhi)(zhi)(zhi)(zhi)量(liang)(liang)(liang)(liang)(liang)取(qu)決(jue)于測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)數據(ju)(ju)(ju)質(zhi)(zhi)(zhi)(zhi)(zhi)量(liang)(liang)(liang)(liang)(liang),低質(zhi)(zhi)(zhi)(zhi)(zhi)量(liang)(liang)(liang)(liang)(liang)數據(ju)(ju)(ju)不(bu)僅影(ying)響(xiang)(xiang)解(jie)(jie)(jie)(jie)(jie)析(xi)結(jie)果(guo)準確性(xing)(xing)(xing)和(he)(he)(he)精密(mi)度(du),還(huan)可能會(hui)誤(wu)導解(jie)(jie)(jie)(jie)(jie)析(xi)思路。解(jie)(jie)(jie)(jie)(jie)析(xi)的(de)(de)目的(de)(de)是認識(shi)腐蝕(shi)(shi)電化(hua)學過程規律和(he)(he)(he)機理,計(ji)(ji)算腐蝕(shi)(shi)參數,預測(ce)(ce)腐蝕(shi)(shi)行(xing)為。低質(zhi)(zhi)(zhi)(zhi)(zhi)量(liang)(liang)(liang)(liang)(liang)解(jie)(jie)(jie)(jie)(jie)析(xi)結(jie)果(guo)和(he)(he)(he)解(jie)(jie)(jie)(jie)(jie)析(xi)模型會(hui)導致(zhi)研(yan)(yan)究工作價(jia)值(zhi)降低。因此,高效EIS研(yan)(yan)究首先(xian)要(yao)設(she)計(ji)(ji)和(he)(he)(he)實施科學的(de)(de)測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)方(fang)案(an),以(yi)期獲得與所研(yan)(yan)究腐蝕(shi)(shi)過程密(mi)切相關(guan)的(de)(de)具有解(jie)(jie)(jie)(jie)(jie)析(xi)價(jia)值(zhi)的(de)(de)高質(zhi)(zhi)(zhi)(zhi)(zhi)量(liang)(liang)(liang)(liang)(liang)阻抗(kang)數據(ju)(ju)(ju)。測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)方(fang)案(an)包括(kuo)測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)方(fang)法和(he)(he)(he)數據(ju)(ju)(ju)可靠(kao)性(xing)(xing)(xing)評價(jia)。測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)結(jie)果(guo)不(bu)僅取(qu)決(jue)于測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)儀(yi)器性(xing)(xing)(xing)能,還(huan)取(qu)決(jue)于電解(jie)(jie)(jie)(jie)(jie)池性(xing)(xing)(xing)能。前者在于選擇合適的(de)(de)商品儀(yi)器,后者通常根據(ju)(ju)(ju)研(yan)(yan)究內(nei)容合理設(she)計(ji)(ji)和(he)(he)(he)組(zu)建,考慮不(bu)周很(hen)容易影(ying)響(xiang)(xiang)測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)數據(ju)(ju)(ju)質(zhi)(zhi)(zhi)(zhi)(zhi)量(liang)(liang)(liang)(liang)(liang)。EIS方(fang)法的(de)(de)重(zhong)要(yao)特點(dian)之(zhi)一(yi)是能夠檢測(ce)(ce)到10-11 Acm-2的(de)(de)極其微弱(ruo)交流(liu)信號,因而(er)適用(yong)于有機涂層、緩(huan)蝕(shi)(shi)劑和(he)(he)(he)純(chun)水等高阻抗(kang)體系研(yan)(yan)究。微弱(ruo)交流(liu)信號不(bu)僅容易受到環境噪聲的(de)(de)影(ying)響(xiang)(xiang),還(huan)因其低頻區響(xiang)(xiang)應速度(du)低,達到穩態(tai)時間長,測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)結(jie)果(guo)存在過渡現象,數據(ju)(ju)(ju)重(zhong)現性(xing)(xing)(xing)差,導致(zhi)測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)的(de)(de)數據(ju)(ju)(ju)質(zhi)(zhi)(zhi)(zhi)(zhi)量(liang)(liang)(liang)(liang)(liang)下降。這不(bu)僅直接影(ying)響(xiang)(xiang)數據(ju)(ju)(ju)解(jie)(jie)(jie)(jie)(jie)析(xi)質(zhi)(zhi)(zhi)(zhi)(zhi)量(liang)(liang)(liang)(liang)(liang),還(huan)會(hui)誤(wu)導解(jie)(jie)(jie)(jie)(jie)析(xi)思路和(he)(he)(he)建模過程。為了確保數據(ju)(ju)(ju)的(de)(de)解(jie)(jie)(jie)(jie)(jie)析(xi)質(zhi)(zhi)(zhi)(zhi)(zhi)量(liang)(liang)(liang)(liang)(liang),需要(yao)測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)后先(xian)進行(xing)測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)數據(ju)(ju)(ju)質(zhi)(zhi)(zhi)(zhi)(zhi)量(liang)(liang)(liang)(liang)(liang)評估,不(bu)符合要(yao)求的(de)(de)測(ce)(ce)量(liang)(liang)(liang)(liang)(liang)數據(ju)(ju)(ju)不(bu)能用(yong)于數據(ju)(ju)(ju)解(jie)(jie)(jie)(jie)(jie)析(xi)。

img_1.png

圖1 碳(tan)鋼點蝕(shi)誘導(dao)期電化學阻抗譜響應[5]


常用(yong)的腐(fu)蝕EIS數(shu)據(ju)(ju)解(jie)析(xi)(xi)有兩種方(fang)(fang)(fang)法(fa),電(dian)(dian)化學(xue)(xue)(xue)(xue)動(dong)力(li)(li)學(xue)(xue)(xue)(xue)模(mo)型(xing)(xing)方(fang)(fang)(fang)法(fa)和(he)模(mo)擬(ni)等效電(dian)(dian)路模(mo)型(xing)(xing)方(fang)(fang)(fang)法(fa)。電(dian)(dian)化學(xue)(xue)(xue)(xue)動(dong)力(li)(li)學(xue)(xue)(xue)(xue)模(mo)型(xing)(xing)方(fang)(fang)(fang)法(fa)是(shi)根據(ju)(ju)腐(fu)蝕過(guo)程特征建立(li)電(dian)(dian)化學(xue)(xue)(xue)(xue)阻(zu)抗響應動(dong)力(li)(li)學(xue)(xue)(xue)(xue)方(fang)(fang)(fang)程,解(jie)析(xi)(xi)和(he)驗證后獲得腐(fu)蝕電(dian)(dian)化學(xue)(xue)(xue)(xue)動(dong)力(li)(li)學(xue)(xue)(xue)(xue)過(guo)程數(shu)學(xue)(xue)(xue)(xue)模(mo)型(xing)(xing),進(jin)而計算腐(fu)蝕電(dian)(dian)化學(xue)(xue)(xue)(xue)參數(shu)和(he)預測腐(fu)蝕行為。雖然這一(yi)直是(shi)傳(chuan)統電(dian)(dian)化學(xue)(xue)(xue)(xue)中(zhong)基本的數(shu)據(ju)(ju)解(jie)析(xi)(xi)方(fang)(fang)(fang)法(fa),但要(yao)求研究者具備一(yi)定的數(shu)學(xue)(xue)(xue)(xue)物理方(fang)(fang)(fang)程和(he)電(dian)(dian)化學(xue)(xue)(xue)(xue)動(dong)力(li)(li)學(xue)(xue)(xue)(xue)基礎。曹楚南在《電(dian)(dian)化學(xue)(xue)(xue)(xue)阻(zu)抗譜導論(lun)》著(zhu)作中(zhong)采用(yong)這一(yi)解(jie)析(xi)(xi)方(fang)(fang)(fang)法(fa)對腐(fu)蝕電(dian)(dian)化學(xue)(xue)(xue)(xue)阻(zu)抗譜原理進(jin)行了嚴謹深入的分析(xi)(xi)論(lun)證,并(bing)介(jie)紹了其在典型(xing)(xing)腐(fu)蝕過(guo)程中(zhong)的應用(yong),是(shi)使(shi)用(yong)這一(yi)方(fang)(fang)(fang)法(fa)的重要(yao)參考。


模(mo)(mo)擬(ni)(ni)等(deng)(deng)效(xiao)(xiao)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)模(mo)(mo)型(xing)(xing)方(fang)法(fa),即電(dian)(dian)(dian)(dian)(dian)模(mo)(mo)擬(ni)(ni)方(fang)法(fa) (electric analog) 采用電(dian)(dian)(dian)(dian)(dian)子(zi)元件組成特(te)定電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)使其與(yu)研究體(ti)系(xi)具有相同的(de)響(xiang)應(ying)規律,進而(er)通過電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)交(jiao)流阻抗(kang)(kang)行為研究動態腐蝕(shi)(shi)(shi)(shi)系(xi)統(tong)的(de)行為和(he)機理。這一方(fang)法(fa)貌似簡單,實(shi)(shi)則也需(xu)要扎(zha)實(shi)(shi)的(de)相關(guan)基礎與(yu)嚴(yan)(yan)(yan)謹的(de)解(jie)(jie)析(xi)(xi)方(fang)法(fa)。近年來由(you)于(yu)EIS方(fang)法(fa)在與(yu)腐蝕(shi)(shi)(shi)(shi)有關(guan)的(de)材料科學、生(sheng)物科學和(he)工程(cheng)(cheng)應(ying)用領域顯(xian)著(zhu)增加,這些領域研究者通常不具備扎(zha)實(shi)(shi)的(de)動力學分(fen)析(xi)(xi)基礎,因而(er)更傾向于(yu)使用易于(yu)理解(jie)(jie)的(de)等(deng)(deng)效(xiao)(xiao)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)模(mo)(mo)型(xing)(xing)方(fang)法(fa)。動力學解(jie)(jie)析(xi)(xi)大師常常質(zhi)疑這一方(fang)法(fa)的(de)科學性(xing)。EIS創(chuang)始人(ren)Sluyters認為模(mo)(mo)擬(ni)(ni)等(deng)(deng)效(xiao)(xiao)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)解(jie)(jie)析(xi)(xi)EIS是(shi)(shi)歧途(tu),“等(deng)(deng)效(xiao)(xiao)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)是(shi)(shi)可以(yi)證明,但是(shi)(shi)不可以(yi)創(chuang)造”[6]。曹楚南也認為模(mo)(mo)擬(ni)(ni)等(deng)(deng)效(xiao)(xiao)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)方(fang)法(fa)解(jie)(jie)析(xi)(xi)阻抗(kang)(kang)譜缺乏嚴(yan)(yan)(yan)謹性(xing)[4]。的(de)確如此(ci),腐蝕(shi)(shi)(shi)(shi)過程(cheng)(cheng)EIS響(xiang)應(ying)與(yu)其相應(ying)的(de)等(deng)(deng)效(xiao)(xiao)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)之間(jian)既不存在嚴(yan)(yan)(yan)格對(dui)應(ying)關(guan)系(xi),也不存在實(shi)(shi)質(zhi)性(xing)聯系(xi)。常見的(de)解(jie)(jie)析(xi)(xi)阻抗(kang)(kang)譜等(deng)(deng)效(xiao)(xiao)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)模(mo)(mo)型(xing)(xing)推導過程(cheng)(cheng)缺乏嚴(yan)(yan)(yan)謹性(xing),模(mo)(mo)型(xing)(xing)缺乏唯一性(xing),有時還會(hui)誤導對(dui)腐蝕(shi)(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)化學過程(cheng)(cheng)機理的(de)理解(jie)(jie)。因此(ci),這一方(fang)法(fa)的(de)解(jie)(jie)析(xi)(xi)程(cheng)(cheng)序需(xu)要規范完(wan)(wan)善。事實(shi)(shi)上(shang),一些復雜(za)體(ti)系(xi)的(de)腐蝕(shi)(shi)(shi)(shi)過程(cheng)(cheng),如不均勻分(fen)布態腐蝕(shi)(shi)(shi)(shi)體(ti)系(xi)中的(de)表面耦合電(dian)(dian)(dian)(dian)(dian)流過程(cheng)(cheng),很難用當前(qian)二(er)端電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)來描述,等(deng)(deng)效(xiao)(xiao)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)模(mo)(mo)型(xing)(xing)方(fang)法(fa)還需(xu)要繼續發(fa)展(zhan)和(he)完(wan)(wan)善。


3 完善腐蝕電化學(xue)阻抗譜等效電路解(jie)析方法的必要性


事(shi)實(shi)(shi)上,最初用(yong)電(dian)(dian)子(zi)學(xue)(xue)中的(de)(de)(de)(de)(de)(de)(de)等(deng)(deng)(deng)效(xiao)電(dian)(dian)路(lu)方(fang)(fang)(fang)(fang)法(fa)(fa)(fa)解(jie)(jie)析(xi)(xi)EIS并非(fei)為(wei)了(le)(le)構建腐(fu)(fu)(fu)(fu)蝕(shi)(shi)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)模(mo)(mo)型(xing),僅僅是(shi)模(mo)(mo)擬(ni)(ni)和理解(jie)(jie)電(dian)(dian)化(hua)(hua)學(xue)(xue)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)的(de)(de)(de)(de)(de)(de)(de)一(yi)(yi)種輔助方(fang)(fang)(fang)(fang)法(fa)(fa)(fa),不(bu)(bu)太關注建模(mo)(mo)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)邏輯嚴(yan)謹性(xing)(xing)和可驗(yan)(yan)證性(xing)(xing)。當(dang)(dang)時(shi)EIS解(jie)(jie)析(xi)(xi)更主(zhu)要(yao)的(de)(de)(de)(de)(de)(de)(de)困難(nan)在(zai)于(yu)電(dian)(dian)化(hua)(hua)學(xue)(xue)參(can)(can)數(shu)計算和阻(zu)抗譜(pu)數(shu)據精確(que)擬(ni)(ni)合(he)技術(shu)。隨著(zhu)計算機(ji)硬件(jian)和軟件(jian)技術(shu)快速(su)發(fa)展,測(ce)量(liang)技術(shu)和參(can)(can)數(shu)擬(ni)(ni)合(he)技術(shu)都(dou)取得(de)長足進步(bu),已(yi)經不(bu)(bu)再是(shi)解(jie)(jie)析(xi)(xi)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)的(de)(de)(de)(de)(de)(de)(de)主(zhu)要(yao)障礙。且(qie)由于(yu)簡單(dan)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)EIS解(jie)(jie)析(xi)(xi)技術(shu)的(de)(de)(de)(de)(de)(de)(de)積累和完善,阻(zu)抗譜(pu)解(jie)(jie)析(xi)(xi)對(dui)象轉移到復(fu)雜(za)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)機(ji)理分(fen)析(xi)(xi)和建立模(mo)(mo)型(xing)方(fang)(fang)(fang)(fang)面。復(fu)雜(za)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)體系不(bu)(bu)僅涉及多電(dian)(dian)極(ji)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng),還涉及多種膜過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)、局部腐(fu)(fu)(fu)(fu)蝕(shi)(shi)的(de)(de)(de)(de)(de)(de)(de)不(bu)(bu)均勻分(fen)布過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)、時(shi)間(jian)演化(hua)(hua)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)、復(fu)合(he)電(dian)(dian)源過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)、復(fu)雜(za)分(fen)布網絡電(dian)(dian)路(lu)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)等(deng)(deng)(deng)等(deng)(deng)(deng)。這些復(fu)雜(za)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)的(de)(de)(de)(de)(de)(de)(de)微分(fen)方(fang)(fang)(fang)(fang)程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)參(can)(can)數(shu)眾(zhong)多,且(qie)相(xiang)(xiang)互作用(yong),動力(li)學(xue)(xue)解(jie)(jie)析(xi)(xi)難(nan)度很大或者無法(fa)(fa)(fa)求解(jie)(jie),很難(nan)獲得(de)相(xiang)(xiang)應的(de)(de)(de)(de)(de)(de)(de)動力(li)學(xue)(xue)方(fang)(fang)(fang)(fang)程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng),非(fei)經數(shu)學(xue)(xue)專業(ye)訓練很難(nan)掌握(wo)。相(xiang)(xiang)對(dui)而(er)言,等(deng)(deng)(deng)效(xiao)電(dian)(dian)路(lu)模(mo)(mo)型(xing)是(shi)一(yi)(yi)種物理模(mo)(mo)擬(ni)(ni)方(fang)(fang)(fang)(fang)法(fa)(fa)(fa),更顯得(de)直觀簡單(dan)且(qie)可以用(yong)于(yu)復(fu)雜(za)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng),受(shou)到廣大非(fei)電(dian)(dian)化(hua)(hua)學(xue)(xue)專業(ye)的(de)(de)(de)(de)(de)(de)(de)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)科研(yan)(yan)和工程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)技術(shu)人員的(de)(de)(de)(de)(de)(de)(de)歡迎和廣泛(fan)使用(yong)。同時(shi),快速(su)擴展放大了(le)(le)等(deng)(deng)(deng)效(xiao)電(dian)(dian)路(lu)解(jie)(jie)析(xi)(xi)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)阻(zu)抗譜(pu)響(xiang)應的(de)(de)(de)(de)(de)(de)(de)先天不(bu)(bu)足,導致解(jie)(jie)析(xi)(xi)過程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)不(bu)(bu)嚴(yan)謹不(bu)(bu)規(gui)范,建立的(de)(de)(de)(de)(de)(de)(de)模(mo)(mo)型(xing)存在(zai)一(yi)(yi)些缺陷而(er)經不(bu)(bu)起嚴(yan)格檢驗(yan)(yan),成為(wei)病態等(deng)(deng)(deng)效(xiao)電(dian)(dian)路(lu)模(mo)(mo)型(xing)。考慮(lv)到當(dang)(dang)前等(deng)(deng)(deng)效(xiao)電(dian)(dian)路(lu)模(mo)(mo)型(xing)方(fang)(fang)(fang)(fang)法(fa)(fa)(fa)應用(yong)范圍和領域快速(su)擴展,不(bu)(bu)嚴(yan)謹不(bu)(bu)規(gui)范的(de)(de)(de)(de)(de)(de)(de)解(jie)(jie)析(xi)(xi)結果(guo)會使研(yan)(yan)究成果(guo)學(xue)(xue)術(shu)質量(liang)下(xia)降,影響(xiang)這一(yi)(yi)方(fang)(fang)(fang)(fang)法(fa)(fa)(fa)的(de)(de)(de)(de)(de)(de)(de)持續(xu)發(fa)展。為(wei)此,需(xu)要(yao)切實(shi)(shi)掌握(wo)這一(yi)(yi)解(jie)(jie)析(xi)(xi)方(fang)(fang)(fang)(fang)法(fa)(fa)(fa)的(de)(de)(de)(de)(de)(de)(de)理論基(ji)礎,消除隨意性(xing)(xing)和不(bu)(bu)確(que)定(ding)性(xing)(xing)的(de)(de)(de)(de)(de)(de)(de)弊病,發(fa)展嚴(yan)謹規(gui)范化(hua)(hua)的(de)(de)(de)(de)(de)(de)(de)解(jie)(jie)析(xi)(xi)程(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)(cheng)序,提(ti)高這一(yi)(yi)方(fang)(fang)(fang)(fang)法(fa)(fa)(fa)的(de)(de)(de)(de)(de)(de)(de)學(xue)(xue)術(shu)價(jia)值,成為(wei)解(jie)(jie)決復(fu)雜(za)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)問題的(de)(de)(de)(de)(de)(de)(de)強(qiang)有力(li)工具。


EIS數(shu)據解析(xi)目的(de)(de)是(shi)(shi)查明腐(fu)(fu)蝕(shi)(shi)機(ji)理(li)和(he)單元過程(cheng)性(xing)質,建(jian)立腐(fu)(fu)蝕(shi)(shi)模(mo)型,進(jin)而計(ji)算腐(fu)(fu)蝕(shi)(shi)參數(shu),預測腐(fu)(fu)蝕(shi)(shi)行為和(he)材料耐蝕(shi)(shi)壽(shou)命(ming)。從這一(yi)(yi)點來說,等效電路(lu)(lu)模(mo)型方(fang)(fang)法(fa)和(he)動(dong)力(li)學方(fang)(fang)法(fa)解析(xi)目標和(he)結果(guo)是(shi)(shi)完(wan)全相同的(de)(de),并(bing)無本質區別(bie)(bie)。差(cha)別(bie)(bie)僅在(zai)于解析(xi)途徑(jing)不同,事實(shi)上也經(jing)常(chang)混合(he)使用。因此,提升等效電路(lu)(lu)模(mo)型解析(xi)方(fang)(fang)法(fa)的(de)(de)嚴謹性(xing)和(he)科(ke)學性(xing),使其不再僅僅是(shi)(shi)論文的(de)(de)花邊裝飾品(pin),與動(dong)力(li)學解析(xi)方(fang)(fang)法(fa)一(yi)(yi)樣,使解析(xi)模(mo)型不僅能夠合(he)理(li)闡述(shu)腐(fu)(fu)蝕(shi)(shi)行為特征和(he)過程(cheng)機(ji)理(li),還能夠用于計(ji)算腐(fu)(fu)蝕(shi)(shi)參數(shu),預測長期腐(fu)(fu)蝕(shi)(shi)行為和(he)材料耐蝕(shi)(shi)壽(shou)命(ming),成為一(yi)(yi)種經(jing)得起理(li)論推敲和(he)應用檢驗的(de)(de)有效解析(xi)工具(ju)。


電(dian)模(mo)擬等(deng)效(xiao)電(dian)路(lu)模(mo)型(xing)方(fang)法是(shi)采用(yong)電(dian)子元(yuan)件組成特定電(dian)路(lu),使其與(yu)腐(fu)蝕過程(cheng)具有相(xiang)同(tong)的(de)電(dian)化(hua)學阻抗譜響應規律(lv),進(jin)而(er)建立腐(fu)蝕過程(cheng)的(de)等(deng)效(xiao)電(dian)路(lu)模(mo)型(xing),研究腐(fu)蝕過程(cheng)行為(wei)和(he)機理。與(yu)動力(li)學方(fang)法相(xiang)比較,等(deng)效(xiao)電(dian)路(lu)模(mo)型(xing)方(fang)法畢竟是(shi)來源(yuan)于電(dian)子電(dian)路(lu)分析的(de)物(wu)理方(fang)法,而(er)腐(fu)蝕是(shi)化(hua)學過程(cheng),兩者間(jian)具有本質區別。模(mo)擬過程(cheng)看起來簡單(dan),實則(ze)邏輯嚴謹(jin)的(de)模(mo)擬過程(cheng)相(xiang)當(dang)復雜(za)。


規范化(hua)模擬等(deng)(deng)(deng)效電(dian)路解(jie)(jie)析(xi)方法(fa)首先需要深入(ru)了(le)解(jie)(jie)等(deng)(deng)(deng)效電(dian)路過(guo)程和(he)腐蝕(shi)過(guo)程之間的(de)相關(guan)(guan)性(xing),查明(ming)兩者間的(de)物理(li)(li)關(guan)(guan)聯和(he)本質差異,才有可(ke)(ke)能奠定(ding)等(deng)(deng)(deng)效電(dian)路解(jie)(jie)析(xi)電(dian)化(hua)學(xue)阻抗譜方法(fa)物理(li)(li)化(hua)學(xue)基(ji)礎(chu)和(he)嚴謹規范的(de)解(jie)(jie)析(xi)路線。由此可(ke)(ke)知(zhi),解(jie)(jie)決上述問(wen)題需要面(mian)對(dui)腐蝕(shi)電(dian)化(hua)學(xue)過(guo)程 (ECP) —EIS—模擬等(deng)(deng)(deng)效電(dian)路 (EQC) 三(san)者間的(de)關(guan)(guan)系,見圖2。

img_2.png

圖2 腐蝕電化學(xue)過程 (ECP) -電化學(xue)阻抗譜(pu) (EIS)-等效電路 (EQC) 的關系


其中,第(di)一(yi)類關(guan)系(xi)(xi)是(shi)(shi)(shi)已(yi)(yi)知和(he)常用的(de),如(ru)(ru)ECP→EIS是(shi)(shi)(shi)測量腐(fu)蝕過(guo)(guo)程的(de)EIS響(xiang)應;EIS→EQC是(shi)(shi)(shi)根據EIS特征(zheng)和(he)數據解(jie)(jie)析(xi)相關(guan)的(de)等效電(dian)路(lu)EQC;EQC→EIS是(shi)(shi)(shi)驗證(zheng)EQC阻抗譜響(xiang)應一(yi)致性(xing)。第(di)二類關(guan)系(xi)(xi)是(shi)(shi)(shi)較困難(nan)的(de),當前尚未(wei)解(jie)(jie)決(jue)的(de),如(ru)(ru)EIS→ECP直(zhi)接解(jie)(jie)析(xi)傳輸函數,如(ru)(ru)ECP→EQC直(zhi)接解(jie)(jie)析(xi)等效電(dian)路(lu)。第(di)三類關(guan)系(xi)(xi)是(shi)(shi)(shi)EQC→ECP驗證(zheng)等效電(dian)路(lu)與腐(fu)蝕過(guo)(guo)程一(yi)致性(xing),即模(mo)型化過(guo)(guo)程。采用動力學模(mo)型方(fang)法取代等效電(dian)路(lu)方(fang)法,上述關(guan)系(xi)(xi)和(he)解(jie)(jie)析(xi)步驟仍(reng)然成立,不過(guo)(guo)是(shi)(shi)(shi)解(jie)(jie)析(xi)和(he)建(jian)模(mo)方(fang)法不同而已(yi)(yi)。


顯然,解析(xi)腐(fu)蝕(shi)(shi)EIS響應的(de)(de)目的(de)(de)是構建(jian)腐(fu)蝕(shi)(shi)過(guo)(guo)程傳(chuan)輸函(han)(han)數或腐(fu)蝕(shi)(shi)過(guo)(guo)程模型(xing)。目前,除了已知的(de)(de)簡單腐(fu)蝕(shi)(shi)過(guo)(guo)程以(yi)外,根(gen)據(ju)第二類關系從腐(fu)蝕(shi)(shi)過(guo)(guo)程直接建(jian)模和(he)根(gen)據(ju)EIS直接解析(xi)傳(chuan)輸函(han)(han)數還是不可(ke)能的(de)(de)。因此(ci),構建(jian)腐(fu)蝕(shi)(shi)過(guo)(guo)程模型(xing)只(zhi)有ECP→EIS→EQC→EQCM (腐(fu)蝕(shi)(shi)過(guo)(guo)程的(de)(de)等效電路(lu)模型(xing)) 是唯(wei)一可(ke)行路(lu)線,其(qi)中(zhong)還必(bi)須(xu)通(tong)(tong)過(guo)(guo)EQC→EIS和(he)EQC→EQCM兩項一致性驗證程序。由此(ci)可(ke)見,建(jian)立腐(fu)蝕(shi)(shi)模型(xing)的(de)(de)ECP→EQCM這一捷徑是走不通(tong)(tong)的(de)(de),可(ke)以(yi)走通(tong)(tong)的(de)(de)路(lu)線只(zhi)有一條:ECP→EIS→EQC→EQCM。


這里需要(yao)(yao)(yao)說明模擬等(deng)(deng)效(xiao)(xiao)電(dian)(dian)路(lu)(lu)(lu) (SEQC) 和(he)(he)(he)EQCM的(de)區(qu)別(bie)。SEQC表(biao)示(shi)該(gai)電(dian)(dian)路(lu)(lu)(lu)與(yu)(yu)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)過(guo)(guo)程(cheng)(cheng)(cheng)等(deng)(deng)效(xiao)(xiao),即(ji)不(bu)管其內部元(yuan)件(jian)性(xing)(xing)質(zhi)和(he)(he)(he)結構方式(shi)如(ru)何,只(zhi)(zhi)要(yao)(yao)(yao)外部電(dian)(dian)壓和(he)(he)(he)電(dian)(dian)流(liu)關系保持不(bu)變(bian)即(ji)為(wei)等(deng)(deng)效(xiao)(xiao)。而(er)(er)(er)模型(xing)(xing) (或公(gong)式(shi)) 則不(bu)同,無論是(shi)(shi)(shi)(shi)物理(li)模型(xing)(xing)還(huan)是(shi)(shi)(shi)(shi)數(shu)學模型(xing)(xing),描述的(de)是(shi)(shi)(shi)(shi)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)過(guo)(guo)程(cheng)(cheng)(cheng)真(zhen)實(shi)的(de)性(xing)(xing)質(zhi)、結構和(he)(he)(he)流(liu)程(cheng)(cheng)(cheng),即(ji)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)機理(li)。等(deng)(deng)效(xiao)(xiao)電(dian)(dian)路(lu)(lu)(lu)模型(xing)(xing)EQCM是(shi)(shi)(shi)(shi)用(yong)電(dian)(dian)路(lu)(lu)(lu)元(yuan)件(jian)和(he)(he)(he)結構來(lai)模擬腐(fu)(fu)(fu)蝕(shi)(shi)(shi)過(guo)(guo)程(cheng)(cheng)(cheng)機理(li)。其不(bu)僅要(yao)(yao)(yao)求(qiu)等(deng)(deng)效(xiao)(xiao)電(dian)(dian)路(lu)(lu)(lu)模型(xing)(xing)的(de)EIS響應與(yu)(yu)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)過(guo)(guo)程(cheng)(cheng)(cheng)等(deng)(deng)效(xiao)(xiao)性(xing)(xing)一致,而(er)(er)(er)且要(yao)(yao)(yao)求(qiu)等(deng)(deng)效(xiao)(xiao)電(dian)(dian)路(lu)(lu)(lu)元(yuan)件(jian)性(xing)(xing)質(zhi)和(he)(he)(he)結構流(liu)程(cheng)(cheng)(cheng)與(yu)(yu)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)過(guo)(guo)程(cheng)(cheng)(cheng)一致。只(zhi)(zhi)有(you)達到這兩(liang)點要(yao)(yao)(yao)求(qiu),才能(neng)稱之為(wei)EQCM。SEQC只(zhi)(zhi)是(shi)(shi)(shi)(shi)強(qiang)(qiang)調(diao)EIS等(deng)(deng)效(xiao)(xiao),而(er)(er)(er)EQCM更注重(zhong)(zhong)于與(yu)(yu)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)過(guo)(guo)程(cheng)(cheng)(cheng)電(dian)(dian)流(liu)和(he)(he)(he)結構一致。前者強(qiang)(qiang)調(diao)與(yu)(yu)EIS的(de)一致性(xing)(xing),后者強(qiang)(qiang)調(diao)與(yu)(yu)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)過(guo)(guo)程(cheng)(cheng)(cheng)的(de)一致性(xing)(xing),兩(liang)者從(cong)定義(yi)到功能(neng)均(jun)具有(you)本質(zhi)區(qu)別(bie)。等(deng)(deng)效(xiao)(xiao)電(dian)(dian)路(lu)(lu)(lu)模型(xing)(xing)是(shi)(shi)(shi)(shi)模擬等(deng)(deng)效(xiao)(xiao)電(dian)(dian)路(lu)(lu)(lu)的(de)升(sheng)級版,但這是(shi)(shi)(shi)(shi)一次飛躍性(xing)(xing)質(zhi)變(bian)的(de)升(sheng)級。模擬等(deng)(deng)效(xiao)(xiao)電(dian)(dian)路(lu)(lu)(lu)只(zhi)(zhi)是(shi)(shi)(shi)(shi)一種未(wei)經證實(shi)的(de)假(jia)設,而(er)(er)(er)等(deng)(deng)效(xiao)(xiao)電(dian)(dian)路(lu)(lu)(lu)模型(xing)(xing)則是(shi)(shi)(shi)(shi)已經證實(shi)的(de)有(you)效(xiao)(xiao)數(shu)學物理(li)模型(xing)(xing),可以(yi)用(yong)于認識(shi)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)機理(li),計算腐(fu)(fu)(fu)蝕(shi)(shi)(shi)參(can)數(shu),預(yu)測腐(fu)(fu)(fu)蝕(shi)(shi)(shi)行為(wei),評價耐蝕(shi)(shi)(shi)性(xing)(xing)壽命(ming),從(cong)而(er)(er)(er)具有(you)重(zhong)(zhong)要(yao)(yao)(yao)的(de)理(li)論意義(yi)和(he)(he)(he)應用(yong)價值。顯(xian)然,模擬等(deng)(deng)效(xiao)(xiao)電(dian)(dian)路(lu)(lu)(lu)驗證確認為(wei)模型(xing)(xing)之前只(zhi)(zhi)能(neng)是(shi)(shi)(shi)(shi)一種假(jia)設,是(shi)(shi)(shi)(shi)不(bu)具備上述模型(xing)(xing)的(de)理(li)論價值和(he)(he)(he)應用(yong)功能(neng)的(de)。


如上(shang)所述,解(jie)析(xi)腐蝕電(dian)化學(xue)阻(zu)抗(kang)譜的(de)(de)(de)(de)目的(de)(de)(de)(de)是建立腐蝕過(guo)程(cheng)的(de)(de)(de)(de)等(deng)(deng)效(xiao)(xiao)電(dian)路(lu)模(mo)型,按照ECPEISEQCEQCMECP的(de)(de)(de)(de)3E (EISEQCEQCM) 解(jie)析(xi)路(lu)線(xian)進行。其中最關(guan)鍵的(de)(de)(de)(de)也是最困難(nan)的(de)(de)(de)(de)步驟(zou)是EQCEQCM,如何進行等(deng)(deng)效(xiao)(xiao)電(dian)路(lu)與腐蝕過(guo)程(cheng)一致性的(de)(de)(de)(de)模(mo)型驗證目前尚(shang)無嚴謹規范的(de)(de)(de)(de)程(cheng)序可以遵循(xun)。為(wei)此,需要(yao)查明ECP、EIS、EQC三者間(jian)的(de)(de)(de)(de)相(xiang)關(guan)性,即它們相(xiang)同點(dian)和不同點(dian),為(wei)尋(xun)找合理嚴謹規范解(jie)析(xi)路(lu)線(xian)查明和奠基(ji)扎實的(de)(de)(de)(de)等(deng)(deng)效(xiao)(xiao)電(dian)路(lu)解(jie)析(xi)方法的(de)(de)(de)(de)理論基(ji)礎。為(wei)此,需要(yao)首先(xian)考慮以下(xia)事實。


其一,基本過(guo)(guo)(guo)程(cheng)(cheng)(cheng)是用(yong)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)元(yuan)(yuan)(yuan)(yuan)(yuan)件(jian)(jian)和結構(gou)來(lai)建(jian)立(li)的腐(fu)蝕(shi)(shi)過(guo)(guo)(guo)程(cheng)(cheng)(cheng)模(mo)(mo)(mo)型。腐(fu)蝕(shi)(shi)單(dan)元(yuan)(yuan)(yuan)(yuan)(yuan)過(guo)(guo)(guo)程(cheng)(cheng)(cheng)用(yong)電(dian)(dian)(dian)(dian)(dian)子(zi)元(yuan)(yuan)(yuan)(yuan)(yuan)件(jian)(jian)模(mo)(mo)(mo)擬(ni)(ni)(ni),腐(fu)蝕(shi)(shi)單(dan)元(yuan)(yuan)(yuan)(yuan)(yuan)平行(xing)/連(lian)續(xu)反應(ying)組(zu)合用(yong)并聯/串聯電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)來(lai)模(mo)(mo)(mo)擬(ni)(ni)(ni)。腐(fu)蝕(shi)(shi)模(mo)(mo)(mo)型建(jian)模(mo)(mo)(mo)質量(liang)則(ze)(ze)取(qu)決于等效(xiao)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)的電(dian)(dian)(dian)(dian)(dian)子(zi)元(yuan)(yuan)(yuan)(yuan)(yuan)件(jian)(jian)和結構(gou)的模(mo)(mo)(mo)擬(ni)(ni)(ni)質量(liang)。電(dian)(dian)(dian)(dian)(dian)子(zi)學中(zhong)(zhong)能夠(gou)模(mo)(mo)(mo)擬(ni)(ni)(ni)腐(fu)蝕(shi)(shi)電(dian)(dian)(dian)(dian)(dian)化學過(guo)(guo)(guo)程(cheng)(cheng)(cheng)的元(yuan)(yuan)(yuan)(yuan)(yuan)件(jian)(jian)僅有電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)、電(dian)(dian)(dian)(dian)(dian)容(rong)和電(dian)(dian)(dian)(dian)(dian)感(gan),加上來(lai)源于動(dong)力學模(mo)(mo)(mo)擬(ni)(ni)(ni)元(yuan)(yuan)(yuan)(yuan)(yuan)件(jian)(jian)Warbung阻(zu)(zu)抗、常相(xiang)(xiang)(xiang)位角元(yuan)(yuan)(yuan)(yuan)(yuan)件(jian)(jian) (CPE)、傳輸線元(yuan)(yuan)(yuan)(yuan)(yuan)件(jian)(jian)、雙(shuang)曲函數元(yuan)(yuan)(yuan)(yuan)(yuan)件(jian)(jian),遠不足以(yi)(yi)描述多種(zhong)多樣的腐(fu)蝕(shi)(shi)過(guo)(guo)(guo)程(cheng)(cheng)(cheng)。因(yin)此,不能夠(gou)直接套(tao)用(yong)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)概念的電(dian)(dian)(dian)(dian)(dian)子(zi)元(yuan)(yuan)(yuan)(yuan)(yuan)件(jian)(jian),而要理解具有腐(fu)蝕(shi)(shi)電(dian)(dian)(dian)(dian)(dian)化學意(yi)義(yi)的電(dian)(dian)(dian)(dian)(dian)子(zi)元(yuan)(yuan)(yuan)(yuan)(yuan)件(jian)(jian),才能構(gou)建(jian)符合腐(fu)蝕(shi)(shi)模(mo)(mo)(mo)型的等效(xiao)元(yuan)(yuan)(yuan)(yuan)(yuan)件(jian)(jian)。另外,不同(tong)于電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中(zhong)(zhong)電(dian)(dian)(dian)(dian)(dian)子(zi)流動(dong)形式(shi),腐(fu)蝕(shi)(shi)過(guo)(guo)(guo)程(cheng)(cheng)(cheng)中(zhong)(zhong)涉及多相(xiang)(xiang)(xiang)多界面(mian)(mian),不同(tong)相(xiang)(xiang)(xiang)中(zhong)(zhong)電(dian)(dian)(dian)(dian)(dian)荷(he)(he)流動(dong)形式(shi)不同(tong)。金屬中(zhong)(zhong)為電(dian)(dian)(dian)(dian)(dian)子(zi)流動(dong),電(dian)(dian)(dian)(dian)(dian)解質溶液中(zhong)(zhong)為離子(zi)流動(dong),鈍化膜(mo)中(zhong)(zhong)為載流子(zi)流動(dong)。電(dian)(dian)(dian)(dian)(dian)荷(he)(he)流經相(xiang)(xiang)(xiang)界面(mian)(mian)則(ze)(ze)必須進行(xing)轉換,以(yi)(yi)保持體系電(dian)(dian)(dian)(dian)(dian)中(zhong)(zhong)性原則(ze)(ze)。再有,電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中(zhong)(zhong)電(dian)(dian)(dian)(dian)(dian)荷(he)(he)為集中(zhong)(zhong)方式(shi)流動(dong),而腐(fu)蝕(shi)(shi)過(guo)(guo)(guo)程(cheng)(cheng)(cheng)中(zhong)(zhong)電(dian)(dian)(dian)(dian)(dian)荷(he)(he)在整個(ge)材(cai)料(liao)表面(mian)(mian)以(yi)(yi)不均(jun)勻分布方式(shi)流動(dong)。這些過(guo)(guo)(guo)程(cheng)(cheng)(cheng)均(jun)無法用(yong)電(dian)(dian)(dian)(dian)(dian)子(zi)元(yuan)(yuan)(yuan)(yuan)(yuan)件(jian)(jian)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)來(lai)模(mo)(mo)(mo)擬(ni)(ni)(ni)。


其二,尋找與(yu)腐蝕(shi)體(ti)系(xi)測定(ding)(ding)EIS具有(you)相(xiang)同(tong)響(xiang)應(ying)的等(deng)(deng)效(xiao)(xiao)電路(lu)。對(dui)于(yu)充分(fen)已(yi)知(zhi)腐蝕(shi)過程(cheng)來(lai)說,可采用已(yi)經確認(ren)(ren)的等(deng)(deng)效(xiao)(xiao)電路(lu)進行(xing)擬合計算來(lai)建立腐蝕(shi)過程(cheng)的等(deng)(deng)效(xiao)(xiao)電路(lu)模(mo)型(xing)。但對(dui)于(yu)部分(fen)未知(zhi)和完全未知(zhi)的腐蝕(shi)過程(cheng)來(lai)說,通過選擇具有(you)相(xiang)同(tong)阻抗譜響(xiang)應(ying)的電路(lu)來(lai)建立其等(deng)(deng)效(xiao)(xiao)電路(lu)必(bi)然遇到唯(wei)一(yi)(yi)(yi)性(xing)問題,即存在多個具有(you)相(xiang)同(tong)阻抗譜響(xiang)應(ying)的電路(lu),需要逐個檢驗,不通過則被(bei)否定(ding)(ding),通過則進行(xing)下一(yi)(yi)(yi)步。認(ren)(ren)定(ding)(ding)唯(wei)一(yi)(yi)(yi)與(yu)腐蝕(shi)過程(cheng)一(yi)(yi)(yi)致等(deng)(deng)效(xiao)(xiao)電路(lu)。等(deng)(deng)效(xiao)(xiao)電路(lu)模(mo)型(xing)一(yi)(yi)(yi)致性(xing)確認(ren)(ren)的重(zhong)要性(xing)顯而易見。


這一問(wen)題起(qi)因于電路(lu)(lu)理論中的等(deng)(deng)效變(bian)換原(yuan)理。即,保持外(wai)部電流-電壓關(guan)系(xi)不變(bian)的電路(lu)(lu)結構間存在等(deng)(deng)效轉(zhuan)換,即保持外(wai)部阻抗響應不變(bian)前提(ti)下可存在多個結構不同的等(deng)(deng)效電路(lu)(lu)。


圖3中(zhong)串/并(bing)聯電(dian)路等效變換(huan)的(de)前提條件是電(dian)路中(zhong)的(de)電(dian)阻和(he)電(dian)容滿(man)足(zu)如下(xia)關系:

R p = R S ω S + 1 ω S , C p = C S ω S + 1(1)

R S = R p ω p + 1 , C S = ω p + 1 ω p C p(2)

ω p = ( ω S R p C p ) 2(3)

式(shi) (1) 為串聯(lian)(lian)電(dian)路(lu)變換(huan)為并(bing)(bing)聯(lian)(lian)電(dian)路(lu)的條(tiao)件(jian)式(shi);式(shi) (2) 為并(bing)(bing)聯(lian)(lian)電(dian)路(lu)變換(huan)為串并(bing)(bing)聯(lian)(lian)電(dian)路(lu)的條(tiao)件(jian)式(shi);式(shi) (3) 為頻率變換(huan)條(tiao)件(jian)式(shi)。其(qi)中,CS為串聯(lian)(lian)電(dian)容;Rs為串聯(lian)(lian)電(dian)阻(zu);Cp為并(bing)(bing)聯(lian)(lian)電(dian)容;Rp為并(bing)(bing)聯(lian)(lian)電(dian)阻(zu);Wp為并(bing)(bing)聯(lian)(lian)電(dian)路(lu)特征頻率;Ws為串聯(lian)(lian)電(dian)路(lu)特征頻率。


根據圖3,只(zhi)(zhi)要滿足式(shi) (1)和(3) 的(de)變換條件,Rs-Cs串(chuan)聯電路就(jiu)能(neng)(neng)夠(gou)全頻(pin)(pin)域等(deng)效(xiao)于圖3b的(de)Cp//Rp并聯電路。同樣,只(zhi)(zhi)要滿足式(shi) (2)和(3) 的(de)變換條件,圖3b的(de)Cp//Rp并聯電路就(jiu)能(neng)(neng)夠(gou)全頻(pin)(pin)域等(deng)效(xiao)于圖3a的(de)Rs-Cs串(chuan)聯電路。即只(zhi)(zhi)要滿足式(shi) (1),(2) 和 (3) 中的(de)電阻、電容和頻(pin)(pin)率(lv)關系,兩個結構不(bu)(bu)同的(de)電路的(de)阻抗譜響應能(neng)(neng)夠(gou)實(shi)現(xian)全頻(pin)(pin)率(lv)范圍一(yi)(yi)致。可以證實(shi),同一(yi)(yi)個電路可具有(you)不(bu)(bu)同形式(shi)的(de)阻抗譜響應;同一(yi)(yi)阻抗譜響應也可具有(you)不(bu)(bu)同等(deng)效(xiao)電路。

img_3.png

圖3 串/并(bing)聯電路等(deng)效變換[5]

 

盡管模(mo)擬(ni)電(dian)路結構(gou)可以等效變(bian)(bian)換,但腐(fu)(fu)蝕(shi)過(guo)(guo)程(cheng)等效電(dian)路模(mo)型不能(neng)進行(xing)等效變(bian)(bian)換,對于滿足(zu)穩(wen)(wen)定性(xing)條件(jian)(jian)和限定演化階(jie)段內,其(qi)描述的(de)(de)腐(fu)(fu)蝕(shi)機(ji)理等效電(dian)路的(de)(de)元件(jian)(jian)性(xing)質和結構(gou)是(shi)對應(ying)于腐(fu)(fu)蝕(shi)宏/微觀過(guo)(guo)程(cheng)的(de)(de),應(ying)該是(shi)唯一(yi)的(de)(de)。很難接受一(yi)個穩(wen)(wen)定腐(fu)(fu)蝕(shi)過(guo)(guo)程(cheng)存在(zai)兩個結構(gou)不同的(de)(de)機(ji)理。如(ru)果EIS測量期(qi)間(jian)腐(fu)(fu)蝕(shi)機(ji)理發生變(bian)(bian)化,則(ze)表明該體系尚不滿足(zu)穩(wen)(wen)定性(xing)條件(jian)(jian),應(ying)該選擇測量時間(jian)更短(duan)的(de)(de)EIS測量參數,或改變(bian)(bian)實驗條件(jian)(jian),使腐(fu)(fu)蝕(shi)過(guo)(guo)程(cheng)在(zai)EIS測量周期(qi)內保持穩(wen)(wen)定不變(bian)(bian)。由此可見,在(zai)解(jie)析EIS時獲得與腐(fu)(fu)蝕(shi)過(guo)(guo)程(cheng)阻抗譜響應(ying)一(yi)致等效電(dian)路的(de)(de)存在(zai)性(xing)是(shi)不完備(bei)(bei)的(de)(de),還需要(yao)檢驗該等效電(dian)路的(de)(de)唯一(yi)性(xing)。只(zhi)有存在(zai)且(qie)唯一(yi)才能(neng)確認可能(neng)是(shi)該腐(fu)(fu)蝕(shi)過(guo)(guo)程(cheng)的(de)(de)等效電(dian)路模(mo)型,否則(ze)只(zhi)能(neng)是(shi)假設(she),而假設(she)不具備(bei)(bei)模(mo)型計(ji)算參數和預測行(xing)為的(de)(de)價值。


4 發展完備腐(fu)蝕電化學阻(zu)抗譜等效電路解析方法的必要步驟


綜(zong)上所述,腐(fu)(fu)蝕(shi)過(guo)程(cheng)的(de)等(deng)(deng)(deng)效(xiao)電(dian)路模型(xing)(xing)方法(fa)(fa)需要(yao)發展(zhan)其理(li)論(lun)(lun)基礎和應用技術,才能(neng)滿足(zu)日益增(zeng)長的(de)腐(fu)(fu)蝕(shi)研究和工程(cheng)應用的(de)需求。為此,不僅(jin)需要(yao)解決EIS等(deng)(deng)(deng)效(xiao)電(dian)路解析方法(fa)(fa)的(de)基礎理(li)論(lun)(lun),還需要(yao)解決在(zai)此基礎理(li)論(lun)(lun)構架上進行ECPEISEQCEQCMECP解析過(guo)程(cheng)中所涉及測量(liang)(liang)EIS數據質量(liang)(liang)評(ping)價、等(deng)(deng)(deng)效(xiao)電(dian)路和EIS一致性評(ping)價、等(deng)(deng)(deng)效(xiao)電(dian)路模型(xing)(xing)解析準(zhun)則、等(deng)(deng)(deng)效(xiao)電(dian)路模型(xing)(xing)和腐(fu)(fu)蝕(shi)過(guo)程(cheng)一致性驗(yan)證、等(deng)(deng)(deng)效(xiao)電(dian)路模型(xing)(xing)驗(yan)證準(zhun)則和驗(yan)證判據、復雜腐(fu)(fu)蝕(shi)過(guo)程(cheng)等(deng)(deng)(deng)效(xiao)電(dian)路解析思路和方法(fa)(fa)、常見病態等(deng)(deng)(deng)效(xiao)電(dian)路模型(xing)(xing)故障檢(jian)測,以及發展(zhan)嚴謹規范(fan)完備的(de)腐(fu)(fu)蝕(shi)電(dian)化學阻抗譜解析路線等(deng)(deng)(deng)問題。為此,作者擬在(zai)本系列論(lun)(lun)文中逐次討論(lun)(lun)以下有關問題。


4.1 腐蝕(shi)EIS等(deng)效電路解(jie)析方法的物理化學基礎


此處(chu)是(shi)指廣義物(wu)理(li)(li)(li)化(hua)學(xue)基礎(chu),其中不僅涉及電(dian)(dian)(dian)(dian)極(ji)動力學(xue),還涉及溶液電(dian)(dian)(dian)(dian)化(hua)學(xue),電(dian)(dian)(dian)(dian)子學(xue)和(he)固體物(wu)理(li)(li)(li)學(xue)基礎(chu)知識。用等(deng)效(xiao)(xiao)電(dian)(dian)(dian)(dian)路(lu)(lu)方法解(jie)(jie)析(xi)腐蝕EIS的(de)(de)目的(de)(de)是(shi)認識腐蝕過(guo)程機制和(he)關鍵步驟,進而(er)建(jian)立(li)腐蝕模型(xing)。這一系(xi)列解(jie)(jie)析(xi)過(guo)程必(bi)須建(jian)立(li)在腐蝕過(guo)程——電(dian)(dian)(dian)(dian)化(hua)學(xue)阻抗譜響應——模擬等(deng)效(xiao)(xiao)電(dian)(dian)(dian)(dian)路(lu)(lu)三(san)者之間的(de)(de)相關性(xing)基礎(chu)上(shang)。如果三(san)者間不具有(you)相關性(xing),解(jie)(jie)析(xi)過(guo)程則無(wu)從談起(qi)。查明(ming)三(san)者間的(de)(de)物(wu)理(li)(li)(li)化(hua)學(xue)相關性(xing),才(cai)能借助于其間密(mi)切(qie)關系(xi)理(li)(li)(li)順合理(li)(li)(li)而(er)扎實(shi)的(de)(de)邏(luo)輯(ji)推理(li)(li)(li)過(guo)程,剔除無(wu)依據隨意性(xing)分(fen)析(xi),依據相關性(xing)找(zhao)到(dao)嚴謹的(de)(de)解(jie)(jie)析(xi)途徑。其中最重要的(de)(de)部分(fen)是(shi)理(li)(li)(li)解(jie)(jie)電(dian)(dian)(dian)(dian)子學(xue)中電(dian)(dian)(dian)(dian)路(lu)(lu)等(deng)效(xiao)(xiao)原理(li)(li)(li)和(he)腐蝕機理(li)(li)(li)唯一性(xing)原理(li)(li)(li)間的(de)(de)差異,腐蝕過(guo)程和(he)等(deng)效(xiao)(xiao)電(dian)(dian)(dian)(dian)路(lu)(lu)過(guo)程中電(dian)(dian)(dian)(dian)位/電(dian)(dian)(dian)(dian)流/阻抗等(deng)電(dian)(dian)(dian)(dian)信號的(de)(de)異同點,等(deng)效(xiao)(xiao)電(dian)(dian)(dian)(dian)路(lu)(lu)模型(xing)元(yuan)件和(he)結構與腐蝕單元(yuan)過(guo)程的(de)(de)關系(xi)。查明(ming)這些問題對于建(jian)立(li)合理(li)(li)(li)的(de)(de)解(jie)(jie)析(xi)思路(lu)(lu)至關重要。


4.2 EIS測量方法(fa)選擇和數據質(zhi)量評價及(ji)其對(dui)解析過程的影響


CEPEIS是腐蝕電化學(xue)阻抗等(deng)效電路譜解析過(guo)程的第(di)一(yi)步,也是影響后續解析過(guo)程順(shun)利與否的關鍵一(yi)步。


如前所述(shu),盡(jin)管現代(dai)EIS測(ce)試(shi)(shi)儀(yi)器在(zai)測(ce)試(shi)(shi)靈敏度、分辨率、輸入阻抗(kang)(kang)、頻響范圍(wei)、響應(ying)速度等方面均已具備(bei)了很(hen)高的(de)性能,提(ti)供(gong)了可(ke)滿(man)足多(duo)種需求(qiu)的(de)測(ce)試(shi)(shi)方法選(xuan)擇和復雜豐富的(de)數據擬合(he)模擬技術。但測(ce)試(shi)(shi)高質量EIS仍主要取決(jue)于使用者的(de)經(jing)驗、理(li)解力和實驗規劃水(shui)平。很(hen)多(duo)測(ce)試(shi)(shi)細節考慮不周會導致(zhi)測(ce)定的(de)腐(fu)蝕(shi)EIS質量不滿(man)足解析要求(qiu)而失效。為了完成(cheng)腐(fu)蝕(shi)行(xing)為規律和腐(fu)蝕(shi)機理(li)的(de)有(you)效研(yan)究,獲得高質量EIS數據是直接關系(xi)到研(yan)究工作成(cheng)功的(de)前提(ti)。作者根據多(duo)年從(cong)事腐(fu)蝕(shi)EIS測(ce)試(shi)(shi)的(de)經(jing)歷,提(ti)供(gong)了從(cong)儀(yi)器選(xuan)擇到電解池(chi)設計,從(cong)測(ce)試(shi)(shi)過程故障排除到阻抗(kang)(kang)譜(pu)質量評價等諸方面細節分析和討論。


4.3 腐蝕過程等效電(dian)路(lu)模(mo)型解析準則——等效電(dian)路(lu)升級為等效電(dian)路(lu)模(mo)型的必(bi)經(jing)之路(lu)


EISEQC是ECPEISEQCEQCMECP解(jie)(jie)(jie)析過程(cheng)中(zhong)最主要的(de)(de)工(gong)作(zuo)(zuo)之一(yi),已經積累了大(da)量成(cheng)(cheng)(cheng)果,稍有(you)經驗的(de)(de)研(yan)究人(ren)員(yuan)都能夠從(cong)EIS響(xiang)應找到(dao)一(yi)些合適的(de)(de)EQC,完成(cheng)(cheng)(cheng)EISEQC步驟(zou),并(bing)采(cai)用合適的(de)(de)擬(ni)合模擬(ni)軟(ruan)件驗證所獲得(de)的(de)(de)SEQC的(de)(de)等效(xiao)性,本文不再贅述。但有(you)效(xiao)的(de)(de)阻抗(kang)譜擬(ni)合并(bing)不能證明該(gai)等效(xiao)電路(lu)(lu)作(zuo)(zuo)為(wei)(wei)模型(xing)是有(you)效(xiao)的(de)(de)[7]。獲得(de)SEQC僅(jin)僅(jin)是部(bu)分解(jie)(jie)(jie)析工(gong)作(zuo)(zuo),除了一(yi)些已經模型(xing)化驗證確(que)認等效(xiao)電路(lu)(lu)模型(xing)之外(wai),還需要進一(yi)步解(jie)(jie)(jie)析和驗證EQCM。完整的(de)(de)解(jie)(jie)(jie)析工(gong)作(zuo)(zuo)是以獲得(de)腐蝕過程(cheng)等效(xiao)電路(lu)(lu)模型(xing)EQCM為(wei)(wei)標志。因此(ci),還需要進一(yi)步完成(cheng)(cheng)(cheng)EQCEQCM解(jie)(jie)(jie)析步驟(zou)。


解析(xi)(xi)腐(fu)蝕過(guo)程(cheng)(cheng)EIS響(xiang)應的目的是(shi)獲得腐(fu)蝕過(guo)程(cheng)(cheng)的等(deng)效(xiao)電(dian)路(lu)模(mo)(mo)型(xing)。其(qi)要(yao)求(qiu)顧名思義極為(wei)(wei)簡單,其(qi)一(yi),與(yu)(yu)(yu)數學表達不(bu)同,該(gai)模(mo)(mo)型(xing)表達形式為(wei)(wei)電(dian)路(lu),即(ji)用電(dian)子元(yuan)件組(zu)成(cheng)的電(dian)路(lu)來描(miao)述腐(fu)蝕過(guo)程(cheng)(cheng);其(qi)二,該(gai)模(mo)(mo)型(xing)與(yu)(yu)(yu)腐(fu)蝕過(guo)程(cheng)(cheng)電(dian)化學阻抗響(xiang)應等(deng)效(xiao);其(qi)三,該(gai)模(mo)(mo)型(xing)組(zu)件性質、結構與(yu)(yu)(yu)腐(fu)蝕單元(yuan)過(guo)程(cheng)(cheng)機(ji)理(li)(li)一(yi)致(zhi)。據此,這也成(cheng)為(wei)(wei)腐(fu)蝕過(guo)程(cheng)(cheng)等(deng)效(xiao)電(dian)路(lu)模(mo)(mo)型(xing)的解析(xi)(xi)準則,(1) EQCEIS等(deng)效(xiao)電(dian)路(lu)模(mo)(mo)型(xing)的EIS響(xiang)應與(yu)(yu)(yu)腐(fu)蝕過(guo)程(cheng)(cheng)一(yi)致(zhi);(2) EQCEQCMECP等(deng)效(xiao)電(dian)路(lu)模(mo)(mo)型(xing)組(zu)件形式和(he)結構與(yu)(yu)(yu)腐(fu)蝕過(guo)程(cheng)(cheng)機(ji)理(li)(li)一(yi)致(zhi)。


如前(qian)所述,測量合格(ge)阻(zu)(zu)(zu)抗(kang)響(xiang)應(ying)(ying)后可根(gen)據阻(zu)(zu)(zu)抗(kang)譜(pu)特征(zheng)組建相應(ying)(ying)的(de)(de)(de)電(dian)路,然后檢(jian)(jian)驗其(qi)阻(zu)(zu)(zu)抗(kang)譜(pu)響(xiang)應(ying)(ying)等(deng)(deng)(deng)效(xiao)(xiao)性(xing),再(zai)檢(jian)(jian)驗其(qi)電(dian)路組件結構(gou)一(yi)(yi)致(zhi)性(xing)。全部(bu)通過后,則可確認(ren)為該腐(fu)(fu)蝕(shi)過程的(de)(de)(de)等(deng)(deng)(deng)效(xiao)(xiao)電(dian)路模型(xing)(xing),完(wan)成(cheng)解析(xi)建模。檢(jian)(jian)驗過程似(si)乎很(hen)簡單(dan)(dan),實際上在(zai)這一(yi)(yi)過程中需要合理解決(jue)(jue)一(yi)(yi)些復雜甚至是困難的(de)(de)(de)問(wen)題。例(li)如,阻(zu)(zu)(zu)抗(kang)譜(pu)解析(xi)有(you)時(shi)會發現存在(zai)多個與腐(fu)(fu)蝕(shi)過程阻(zu)(zu)(zu)抗(kang)譜(pu)一(yi)(yi)致(zhi)的(de)(de)(de)等(deng)(deng)(deng)效(xiao)(xiao)電(dian)路,而與腐(fu)(fu)蝕(shi)過程機理一(yi)(yi)致(zhi)的(de)(de)(de)等(deng)(deng)(deng)效(xiao)(xiao)電(dian)路模型(xing)(xing)只能有(you)一(yi)(yi)個,從而需要進一(yi)(yi)步(bu)檢(jian)(jian)驗哪一(yi)(yi)個是合格(ge)的(de)(de)(de)等(deng)(deng)(deng)效(xiao)(xiao)電(dian)路。再(zai)如,有(you)時(shi)會根(gen)據單(dan)(dan)容(rong)抗(kang)弧(hu)阻(zu)(zu)(zu)抗(kang)響(xiang)應(ying)(ying)獲(huo)得(de)雙(shuang)時(shi)間常數等(deng)(deng)(deng)效(xiao)(xiao)電(dian)路;或者(zhe)反之,根(gen)據雙(shuang)容(rong)抗(kang)弧(hu)響(xiang)應(ying)(ying)獲(huo)得(de)單(dan)(dan)時(shi)間常數的(de)(de)(de)等(deng)(deng)(deng)效(xiao)(xiao)電(dian)路。盡管兩者(zhe)阻(zu)(zu)(zu)抗(kang)譜(pu)響(xiang)應(ying)(ying)一(yi)(yi)致(zhi),也要解決(jue)(jue)結構(gou)差(cha)異問(wen)題。


4.4 等(deng)效電路與腐蝕過程阻抗譜一致(zhi)性驗證:EQCEIS


在腐(fu)蝕(shi)電(dian)化學(xue)阻(zu)(zu)抗(kang)譜等(deng)(deng)(deng)效(xiao)電(dian)路解(jie)(jie)析方(fang)法(fa)中的(de)(de)(de)“等(deng)(deng)(deng)效(xiao)”是(shi)指解(jie)(jie)析的(de)(de)(de)等(deng)(deng)(deng)效(xiao)電(dian)路的(de)(de)(de)模擬EIS與(yu)(yu)實測的(de)(de)(de)腐(fu)蝕(shi)過程阻(zu)(zu)抗(kang)譜響應(ying)在全頻(pin)率范圍(wei)一(yi)致。這種說法(fa)與(yu)(yu)電(dian)子學(xue)中“等(deng)(deng)(deng)效(xiao)即為(wei)外電(dian)路電(dian)壓/電(dian)流關系不(bu)變”說法(fa)的(de)(de)(de)意(yi)義(yi)是(shi)一(yi)致的(de)(de)(de)。有(you)些研(yan)究者常常認為(wei)這是(shi)阻(zu)(zu)抗(kang)譜解(jie)(jie)析成功完成的(de)(de)(de)標志,認為(wei)該(gai)等(deng)(deng)(deng)效(xiao)電(dian)路即為(wei)腐(fu)蝕(shi)過程的(de)(de)(de)模型。前述(shu)分析表明(ming),完成這一(yi)步驟(zou)是(shi)建模過程確(que)定(ding)為(wei)等(deng)(deng)(deng)效(xiao)的(de)(de)(de)部分,尚不(bu)能(neng)確(que)認是(shi)腐(fu)蝕(shi)過程模型。兩者的(de)(de)(de)擬合精度(du)(du)自然(ran)(ran)也不(bu)具備確(que)認模型的(de)(de)(de)功能(neng),僅是(shi)等(deng)(deng)(deng)效(xiao)電(dian)路的(de)(de)(de)模擬精度(du)(du)。阻(zu)(zu)抗(kang)譜并(bing)非獨立技術,模型有(you)效(xiao)性驗證還需(xu)要其他輔(fu)助技術[7]。雖然(ran)(ran)如此(ci),等(deng)(deng)(deng)效(xiao)電(dian)路與(yu)(yu)腐(fu)蝕(shi)過程阻(zu)(zu)抗(kang)譜一(yi)致性確(que)認仍然(ran)(ran)是(shi)解(jie)(jie)析過程的(de)(de)(de)不(bu)可缺少(shao)的(de)(de)(de)重要步驟(zou)之一(yi)。


4.5 等效電路與腐(fu)蝕過(guo)程一致性驗(yan)證:EQCEQCMECP


如前所述,等(deng)(deng)效(xiao)(xiao)(xiao)電(dian)(dian)路(lu)升級(ji)為(wei)等(deng)(deng)效(xiao)(xiao)(xiao)電(dian)(dian)路(lu)模(mo)型(xing)EQCEQCMECP,必(bi)須(xu)進行(xing)等(deng)(deng)效(xiao)(xiao)(xiao)電(dian)(dian)路(lu)過(guo)程(cheng)和腐蝕(shi)過(guo)程(cheng)一致性驗證,通(tong)過(guo)則(ze)為(wei)模(mo)型(xing),不(bu)通(tong)過(guo)則(ze)不(bu)能(neng)成為(wei)模(mo)型(xing)。這是3E解析程(cheng)序的關鍵步驟之(zhi)一。


等效電(dian)(dian)(dian)路(lu)(lu)模(mo)型(xing)檢驗判據(ju)是所建等效電(dian)(dian)(dian)路(lu)(lu)與腐(fu)(fu)(fu)蝕(shi)(shi)(shi)過(guo)程(cheng)(cheng)性(xing)(xing)質和(he)結(jie)構(gou)一致,能(neng)夠(gou)有效模(mo)擬(ni)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)過(guo)程(cheng)(cheng)。腐(fu)(fu)(fu)蝕(shi)(shi)(shi)模(mo)型(xing)用等效電(dian)(dian)(dian)路(lu)(lu)組件(jian)性(xing)(xing)質來(lai)模(mo)擬(ni)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)基(ji)本單元過(guo)程(cheng)(cheng)和(he)結(jie)構(gou)。腐(fu)(fu)(fu)蝕(shi)(shi)(shi)過(guo)程(cheng)(cheng)模(mo)擬(ni)等效組件(jian)性(xing)(xing)質包括組件(jian)屬性(xing)(xing)、位置(zhi)和(he)連接關系。腐(fu)(fu)(fu)蝕(shi)(shi)(shi)過(guo)程(cheng)(cheng)等效電(dian)(dian)(dian)路(lu)(lu)模(mo)型(xing)不僅(jin)能(neng)夠(gou)模(mo)擬(ni)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)過(guo)程(cheng)(cheng)機理,還能(neng)夠(gou)計算腐(fu)(fu)(fu)蝕(shi)(shi)(shi)參數,預測腐(fu)(fu)(fu)蝕(shi)(shi)(shi)行為和(he)材料耐蝕(shi)(shi)(shi)壽命(ming),設計腐(fu)(fu)(fu)蝕(shi)(shi)(shi)監測和(he)控制方法。這也是腐(fu)(fu)(fu)蝕(shi)(shi)(shi)項目(mu)研究的最終(zhong)目(mu)標。但(dan)達到這一步目(mu)標并非易(yi)事(shi),需要(yao)經歷(li)一系列嚴格的驗證過(guo)程(cheng)(cheng)。


4.6 等效(xiao)電路(lu)腐(fu)蝕模型驗證判據(ju)—白(bai)腐(fu)蝕組件(WCE)


EQCEQCMECP模型(xing)驗(yan)證(zheng)(zheng)(zheng)(zheng)(zheng)是(shi)(shi)關系到所建等效電路是(shi)(shi)否成(cheng)立為模型(xing)的必不(bu)可(ke)少的重(zhong)要步(bu)(bu)驟(zou)(zou)(zou),也是(shi)(shi)整個(ge)解(jie)(jie)析(xi)過程成(cheng)敗的決定性環節。在EQC驗(yan)證(zheng)(zheng)(zheng)(zheng)(zheng)為EQCM以(yi)前,只能(neng)(neng)(neng)是(shi)(shi)不(bu)具備模型(xing)價(jia)值假設。為了進行有(you)效的模型(xing)驗(yan)證(zheng)(zheng)(zheng)(zheng)(zheng),需要準備盡可(ke)能(neng)(neng)(neng)多的輔助證(zheng)(zheng)(zheng)(zheng)(zheng)據。因此,解(jie)(jie)析(xi)腐蝕過程之前就(jiu)應該考(kao)慮(lv)整個(ge)ECPEISEQCEQCMECP測試和解(jie)(jie)析(xi)過程細(xi)節,盡可(ke)能(neng)(neng)(neng)為模型(xing)驗(yan)證(zheng)(zheng)(zheng)(zheng)(zheng)步(bu)(bu)驟(zou)(zou)(zou)提供充分的驗(yan)證(zheng)(zheng)(zheng)(zheng)(zheng)素材和證(zheng)(zheng)(zheng)(zheng)(zheng)據,才能(neng)(neng)(neng)確保明細(xi)驗(yan)證(zheng)(zheng)(zheng)(zheng)(zheng)步(bu)(bu)驟(zou)(zou)(zou)順利通過。


通(tong)常有兩(liang)條(tiao)模(mo)型(xing)驗(yan)(yan)證(zheng)(zheng)(zheng)路線可(ke)選。其(qi)一是(shi)正面論(lun)證(zheng)(zheng)(zheng)法,與(yu)動力學方法類似(si),從(cong)基本假(jia)設開(kai)始,經歷嚴謹(jin)邏(luo)輯路線數據(ju)分析和建模(mo),并進(jin)行(xing)第(di)三方模(mo)型(xing)驗(yan)(yan)證(zheng)(zheng)(zheng)確(que)認與(yu)腐(fu)蝕過程一致(zhi)性。其(qi)中(zhong)任何(he)步驟都(dou)不能(neng)(neng)存(cun)在數據(ju)解析和邏(luo)輯推(tui)理缺陷(xian)(xian),方能(neng)(neng)夠通(tong)過模(mo)型(xing)驗(yan)(yan)證(zheng)(zheng)(zheng)。其(qi)二是(shi)反(fan)面驗(yan)(yan)證(zheng)(zheng)(zheng)法,分析審查模(mo)型(xing)候(hou)選等(deng)效電路的邏(luo)輯結構缺陷(xian)(xian),無任何(he)缺陷(xian)(xian)則通(tong)過為模(mo)型(xing),有任一缺陷(xian)(xian)存(cun)在則不通(tong)過。


與(yu)EIS動力(li)學解析法(fa)不(bu)同,等(deng)效電(dian)(dian)路(lu)解析EIS過程中的(de)(de)建立候(hou)(hou)選等(deng)效電(dian)(dian)路(lu)的(de)(de)方法(fa)是模(mo)擬(ni)法(fa),即根據阻(zu)抗譜響應特征分(fen)析和(he)推(tui)測可能的(de)(de)等(deng)效電(dian)(dian)路(lu)組件和(he)結構,并進(jin)(jin)行(xing)阻(zu)抗譜擬(ni)合與(yu)模(mo)擬(ni)。與(yu)測定(ding)阻(zu)抗譜一(yi)致成(cheng)為(wei)候(hou)(hou)選等(deng)效電(dian)(dian)路(lu),不(bu)一(yi)致則淘汰(tai)出局。其結果優(you)劣常(chang)常(chang)取決于(yu)解析者的(de)(de)經驗(yan)和(he)判斷(duan)力(li),因而存(cun)在嚴(yan)謹(jin)動力(li)學專家(jia)所詬(gou)病的(de)(de)不(bu)確定(ding)性(xing)(xing)和(he)隨意性(xing)(xing)。消除這種不(bu)確定(ding)性(xing)(xing)的(de)(de)方法(fa)就(jiu)是進(jin)(jin)行(xing)嚴(yan)格的(de)(de)模(mo)型驗(yan)證(zheng)(zheng)。顯(xian)然(ran),因等(deng)效電(dian)(dian)路(lu)解析法(fa)并沒有經歷嚴(yan)謹(jin)分(fen)析和(he)邏(luo)輯論證(zheng)(zheng)過程,進(jin)(jin)行(xing)正(zheng)面(mian)驗(yan)證(zheng)(zheng)其可靠(kao)性(xing)(xing)唯(wei)一(yi)性(xing)(xing)不(bu)僅需(xu)(xu)要窮舉所有可能候(hou)(hou)選等(deng)效電(dian)(dian)路(lu),而且需(xu)(xu)要逐層(ceng)次進(jin)(jin)行(xing)嚴(yan)謹(jin)分(fen)析論證(zheng)(zheng),顯(xian)然(ran)極為(wei)困難。選擇反面(mian)驗(yan)證(zheng)(zheng)法(fa)則是可行(xing)的(de)(de)高(gao)效途徑。驗(yan)證(zheng)(zheng)是不(bu)需(xu)(xu)要嚴(yan)謹(jin)分(fen)析和(he)論證(zheng)(zheng),只需(xu)(xu)驗(yan)證(zheng)(zheng)是否存(cun)在缺陷(xian)即可否定(ding)模(mo)型。


因此,這一(yi)驗證方法的(de)(de)關(guan)鍵工具(ju)是檢驗判(pan)據(ju)(ju),該檢驗判(pan)據(ju)(ju)必須經(jing)過(guo)嚴(yan)謹可(ke)(ke)靠性(xing)(xing)論(lun)證,或已(yi)(yi)經(jing)歷廣泛應用(yong)(yong)確(que)認其(qi)可(ke)(ke)靠性(xing)(xing)。已(yi)(yi)經(jing)歷長(chang)期研究工作確(que)認可(ke)(ke)靠性(xing)(xing)的(de)(de)典(dian)型腐蝕電(dian)(dian)化學過(guo)程等效電(dian)(dian)路(lu)(lu)模(mo)型組件性(xing)(xing)質和連接方式均具(ju)有(you)(you)各自(zi)特征,已(yi)(yi)證實為WCE,可(ke)(ke)用(yong)(yong)作檢驗等效電(dian)(dian)路(lu)(lu)模(mo)型一(yi)致性(xing)(xing)判(pan)據(ju)(ju)。如,雙電(dian)(dian)層電(dian)(dian)容、電(dian)(dian)荷遷移電(dian)(dian)阻(zu)(zu)、極化電(dian)(dian)阻(zu)(zu)、擴(kuo)散阻(zu)(zu)抗、涂層電(dian)(dian)容和電(dian)(dian)阻(zu)(zu)等。這些判(pan)據(ju)(ju)來源于大量公(gong)開發(fa)表的(de)(de)研究成(cheng)果(guo),其(qi)可(ke)(ke)靠性(xing)(xing)毋庸置疑。隨著新腐蝕體(ti)系(xi)研究工作的(de)(de)發(fa)表,還會有(you)(you)新的(de)(de)驗證判(pan)據(ju)(ju)可(ke)(ke)以采用(yong)(yong),經(jing)發(fa)展可(ke)(ke)形成(cheng)WCE數據(ju)(ju)庫,以供模(mo)型驗證時調用(yong)(yong)。可(ke)(ke)以推斷,隨著WCE數據(ju)(ju)庫發(fa)展,模(mo)擬等效電(dian)(dian)路(lu)(lu)SEQC的(de)(de)模(mo)型驗證過(guo)程會越(yue)來越(yue)簡單有(you)(you)效,復雜腐蝕體(ti)系(xi)EIS解析過(guo)程也會變得更加簡潔(jie)有(you)(you)效。


4.7 復雜腐蝕(shi)過程(cheng)等效(xiao)電路解(jie)析(xi)思路


經(jing)(jing)歷多(duo)(duo)年的(de)研(yan)(yan)究和(he)積(ji)累,腐(fu)(fu)蝕(shi)(shi)科(ke)學與(yu)工程研(yan)(yan)究對(dui)象已(yi)經(jing)(jing)從(cong)簡單體(ti)系(xi)(xi)(xi)進入(ru)復(fu)(fu)雜(za)體(ti)系(xi)(xi)(xi)。復(fu)(fu)雜(za)腐(fu)(fu)蝕(shi)(shi)體(ti)系(xi)(xi)(xi)主要特點(dian)是(shi)多(duo)(duo)相多(duo)(duo)界面(mian)過(guo)程動態分(fen)布(bu)耦合體(ti)系(xi)(xi)(xi)。由(you)于實際腐(fu)(fu)蝕(shi)(shi)現(xian)象皆(jie)以復(fu)(fu)雜(za)體(ti)系(xi)(xi)(xi)形式發生于工程應用(yong)環境中,近年來(lai)腐(fu)(fu)蝕(shi)(shi)EIS解(jie)析工作(zuo)正在面(mian)對(dui)越(yue)來(lai)越(yue)多(duo)(duo)的(de)復(fu)(fu)雜(za)腐(fu)(fu)蝕(shi)(shi)體(ti)系(xi)(xi)(xi)。其(qi)中的(de)典型實例是(shi)金(jin)屬/溶液界面(mian)中增加了膜(mo)(mo)(mo)相,如有機(ji)涂(tu)層膜(mo)(mo)(mo)、無(wu)機(ji)涂(tu)層膜(mo)(mo)(mo)、金(jin)屬涂(tu)鍍(du)層膜(mo)(mo)(mo)、鈍化(hua)膜(mo)(mo)(mo)、化(hua)學轉化(hua)膜(mo)(mo)(mo)、腐(fu)(fu)蝕(shi)(shi)產物膜(mo)(mo)(mo)、緩蝕(shi)(shi)劑(ji)膜(mo)(mo)(mo)、微生物膜(mo)(mo)(mo)、疏水膜(mo)(mo)(mo)、自主裝(zhuang)膜(mo)(mo)(mo)、導電(dian)高分(fen)子膜(mo)(mo)(mo)等,簡稱為腐(fu)(fu)蝕(shi)(shi)膜(mo)(mo)(mo)。目前所(suo)涉及腐(fu)(fu)蝕(shi)(shi)膜(mo)(mo)(mo)的(de)種類不低于十數種,導電(dian)性(xing)(xing)、孔隙率等膜(mo)(mo)(mo)的(de)性(xing)(xing)質(zhi)也分(fen)布(bu)很寬廣。文獻所(suo)見電(dian)化(hua)學阻抗(kang)譜解(jie)析腐(fu)(fu)蝕(shi)(shi)膜(mo)(mo)(mo)作(zuo)用(yong)和(he)機(ji)理的(de)思路尚不清晰(xi),解(jie)析過(guo)程嚴謹性(xing)(xing)和(he)規(gui)范(fan)性(xing)(xing)存在質(zhi)疑,導致多(duo)(duo)數解(jie)析模(mo)型可靠性(xing)(xing)存在較大的(de)不確(que)定性(xing)(xing)。


發(fa)展(zhan)復雜腐蝕體系電(dian)(dian)(dian)(dian)化(hua)(hua)學(xue)阻(zu)抗(kang)譜等(deng)效(xiao)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)模型解(jie)析方(fang)法的(de)途徑不外(wai)乎(hu)以下兩種(zhong),其(qi)一是根據(ju)膜(mo)(mo)阻(zu)抗(kang)及其(qi)變化(hua)(hua)的(de)高低簡化(hua)(hua)電(dian)(dian)(dian)(dian)流支路(lu)(lu)(lu)和等(deng)效(xiao)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)模型;其(qi)二是分析各種(zhong)膜(mo)(mo)的(de)厚度、孔隙率、電(dian)(dian)(dian)(dian)導(dao)率、導(dao)電(dian)(dian)(dian)(dian)機制等(deng)基(ji)本(ben)電(dian)(dian)(dian)(dian)化(hua)(hua)學(xue)屬性劃分典型膜(mo)(mo)類別,研究不同類別阻(zu)抗(kang)響(xiang)(xiang)應(ying)特征及其(qi)等(deng)效(xiao)組件結構(gou)和鑒別方(fang)法,并用于解(jie)析過程中。需(xu)要根據(ju)這一思路(lu)(lu)(lu)查(cha)明膜(mo)(mo)屬性與電(dian)(dian)(dian)(dian)化(hua)(hua)學(xue)阻(zu)抗(kang)譜響(xiang)(xiang)應(ying)的(de)關系,進而發(fa)展(zhan)相應(ying)的(de)等(deng)效(xiao)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)表達技術。


除了腐(fu)(fu)蝕(shi)膜(mo)以外,復(fu)雜(za)(za)(za)腐(fu)(fu)蝕(shi)體(ti)系還體(ti)現在(zai)腐(fu)(fu)蝕(shi)過(guo)程(cheng)空間和(he)時(shi)間分(fen)布性(xing)(xing)、動態(tai)性(xing)(xing)和(he)耦合性(xing)(xing)等。這些(xie)特征在(zai)實際(ji)腐(fu)(fu)蝕(shi)過(guo)程(cheng)中以點(dian)蝕(shi)、縫(feng)蝕(shi)、焊縫(feng)腐(fu)(fu)蝕(shi)、應力腐(fu)(fu)蝕(shi)等不(bu)同的局部(bu)腐(fu)(fu)蝕(shi)形式以及負阻抗響(xiang)應[8]廣泛存在(zai)。如何用EIS等效(xiao)電路方法模擬(ni)這些(xie)復(fu)雜(za)(za)(za)腐(fu)(fu)蝕(shi)狀態(tai)和(he)過(guo)程(cheng)尚需(xu)開發(fa)新思(si)路。作者(zhe)擬(ni)在(zai)后(hou)續工作中系統分(fen)析這些(xie)過(guo)程(cheng)的基本阻抗響(xiang)應特征并進(jin)行分(fen)類(lei)建(jian)模,以期建(jian)立這些(xie)復(fu)雜(za)(za)(za)腐(fu)(fu)蝕(shi)體(ti)系適用的等效(xiao)電路解析路線。


4.8 常見病態等效電路模型故障檢測


由于當前等(deng)效電路解(jie)(jie)析(xi)(xi)電化(hua)學阻(zu)抗譜(pu)方法本(ben)身存在解(jie)(jie)析(xi)(xi)過程不(bu)嚴謹、不(bu)規范等(deng)先天不(bu)足,加之(zhi)腐(fu)蝕過程復(fu)雜(za)性(xing),存在缺陷的病態(tai)等(deng)效電路模型常(chang)常(chang)見諸于國內(nei)外高(gao)等(deng)級腐(fu)蝕期刊發表(biao)的研究(jiu)論文中[9,10],有些甚至被經常(chang)引用,這(zhe)是(shi)(shi)一個必須加以關注(zhu)的事實,也是(shi)(shi)本(ben)文撰寫的初始推動力。


論文(wen)擬在這一部(bu)分分析(xi)討論從已發表(biao)論文(wen)中提取的(de)(de)若干病態腐蝕等效(xiao)電路(lu)及(ji)(ji)其模型的(de)(de)缺陷性質(zhi)、成因以及(ji)(ji)修(xiu)正方法,目的(de)(de)是(shi)從應(ying)用角度完善腐蝕電化學阻抗譜等效(xiao)電路(lu)解(jie)析(xi)方法。事實上,常見的(de)(de)病態等效(xiao)電路(lu)模型缺陷表(biao)現(xian)形式多種多樣,都可以根據前文(wen)建立的(de)(de)ECPEISEQCEQCMECP嚴謹(jin)規(gui)范的(de)(de)3E (EISEQCEQCM) 解(jie)析(xi)程(cheng)序審查和修(xiu)正。


4.9 嚴謹(jin)規范(fan)完備的腐蝕EIS 3E解析路線(xian)圖


如(ru)(ru)前(qian)所述,等效電路解析(xi)(xi)方(fang)法貌似簡單易用,如(ru)(ru)以建立模型為(wei)目(mu)標,需要經歷多個(ge)分析(xi)(xi)驗證步驟才(cai)能完成。為(wei)達此目(mu)標,必須嚴謹地規(gui)范化解析(xi)(xi)程序,增(zeng)強邏輯性,降(jiang)低不(bu)確定(ding)性,才(cai)能獲得具有較高(gao)學(xue)術價值的腐蝕模型。


為此,在(zai)上述工作(zuo)基礎(chu)上,將匯總形(xing)(xing)成(cheng)完備腐蝕電(dian)化(hua)學阻抗譜等效(xiao)電(dian)路(lu)(lu)(lu)解(jie)析(xi)方(fang)法(fa)(fa)路(lu)(lu)(lu)線圖,形(xing)(xing)成(cheng)嚴(yan)謹規范化(hua)解(jie)析(xi)規則。即使專業基礎(chu)不(bu)(bu)同(tong)、研究體系不(bu)(bu)同(tong)、解(jie)析(xi)方(fang)法(fa)(fa)不(bu)(bu)同(tong),對(dui)于同(tong)一研究體系遵守(shou)同(tong)一解(jie)析(xi)規則,其解(jie)析(xi)結果即使存(cun)在(zai)差異也具有(you)明(ming)確(que)的可比性(xing),會(hui)顯著消除當(dang)前(qian)等效(xiao)電(dian)路(lu)(lu)(lu)解(jie)析(xi)方(fang)法(fa)(fa)存(cun)在(zai)的不(bu)(bu)確(que)定性(xing)和隨意(yi)性(xing),提(ti)高這一解(jie)析(xi)方(fang)法(fa)(fa)的科學價值和應用價值。


作者擬對上述9項工作內容進行深入研(yan)(yan)究(jiu)(jiu)、分析和(he)討論,并將在后續系列(lie)論文(wen)中陸續報導。其目(mu)的是研(yan)(yan)究(jiu)(jiu)和(he)發展嚴謹規范腐蝕過程電化(hua)學(xue)阻抗譜等(deng)效電路模型(xing)解(jie)析方(fang)法(fa),為廣大(da)腐蝕科研(yan)(yan)人員提供(gong)一種可(ke)靠易用的腐蝕電化(hua)學(xue)研(yan)(yan)究(jiu)(jiu)工具。


5 結束語


盡管等(deng)(deng)效(xiao)電(dian)(dian)(dian)路(lu)(lu)模型(xing)解(jie)(jie)(jie)(jie)析(xi)(xi)腐(fu)(fu)蝕(shi)(shi)(shi)EIS方(fang)法(fa)(fa)存在推理(li)(li)不嚴謹(jin),無(wu)實(shi)質聯系(xi)(xi)形式模擬等(deng)(deng)缺陷,因其(qi)(qi)方(fang)法(fa)(fa)簡單實(shi)用而人氣廣泛,尤其(qi)(qi)適用于復(fu)雜腐(fu)(fu)蝕(shi)(shi)(shi)體系(xi)(xi)。如能理(li)(li)順(shun)夯實(shi)其(qi)(qi)理(li)(li)論基礎(chu),規(gui)劃其(qi)(qi)解(jie)(jie)(jie)(jie)析(xi)(xi)程序,充實(shi)其(qi)(qi)檢(jian)驗判據,完善腐(fu)(fu)蝕(shi)(shi)(shi)阻抗(kang)(kang)譜(pu)(pu)(pu)數據庫,定能成為腐(fu)(fu)蝕(shi)(shi)(shi)研究強力工具(ju)。為此,本文對(dui)當前腐(fu)(fu)蝕(shi)(shi)(shi)EIS等(deng)(deng)效(xiao)電(dian)(dian)(dian)路(lu)(lu)解(jie)(jie)(jie)(jie)析(xi)(xi)方(fang)法(fa)(fa)的特點和(he)(he)現(xian)狀,發展(zhan)(zhan)和(he)(he)完善等(deng)(deng)效(xiao)電(dian)(dian)(dian)路(lu)(lu)解(jie)(jie)(jie)(jie)析(xi)(xi)腐(fu)(fu)蝕(shi)(shi)(shi)EIS方(fang)法(fa)(fa)的必要性和(he)(he)可(ke)行(xing)(xing)性進行(xing)(xing)了分析(xi)(xi)和(he)(he)討論,提(ti)出發展(zhan)(zhan)完備(bei)等(deng)(deng)效(xiao)電(dian)(dian)(dian)路(lu)(lu)解(jie)(jie)(jie)(jie)析(xi)(xi)方(fang)法(fa)(fa)的可(ke)行(xing)(xing)步驟,包括解(jie)(jie)(jie)(jie)析(xi)(xi)方(fang)法(fa)(fa)物理(li)(li)化(hua)(hua)學基礎(chu)、解(jie)(jie)(jie)(jie)析(xi)(xi)模型(xing)驗證與判據、病態等(deng)(deng)效(xiao)電(dian)(dian)(dian)路(lu)(lu)模型(xing)起因、復(fu)雜腐(fu)(fu)蝕(shi)(shi)(shi)電(dian)(dian)(dian)化(hua)(hua)學阻抗(kang)(kang)譜(pu)(pu)(pu)解(jie)(jie)(jie)(jie)析(xi)(xi)思(si)路(lu)(lu)和(he)(he)規(gui)范的EIS等(deng)(deng)效(xiao)電(dian)(dian)(dian)路(lu)(lu)模型(xing)解(jie)(jie)(jie)(jie)析(xi)(xi)程序等(deng)(deng)問題進行(xing)(xing)探索,以期筑石鋪路(lu)(lu),拋磚引玉,發展(zhan)(zhan)完備(bei)嚴謹(jin)規(gui)范的腐(fu)(fu)蝕(shi)(shi)(shi)電(dian)(dian)(dian)化(hua)(hua)學阻抗(kang)(kang)譜(pu)(pu)(pu)等(deng)(deng)效(xiao)電(dian)(dian)(dian)路(lu)(lu)解(jie)(jie)(jie)(jie)析(xi)(xi)和(he)(he)建(jian)模技(ji)術。