5.1 Electrode potential is the reversible work that is required to transfer a unit of positive charge between the surface in question and a reference electrode through the electrolyte that is in contact with both electrodes. The sign of the electrode potential is determined by the Gibbs Stockholm Convention described in Practice G3.
5.2 The electrode potential of a surface is related to the Gibbs free energy of the oxidation/reduction reactions occurring at the surface in question compared to the Gibbs free energy of the reactions occurring on the reference electrode surface.4
5.3 Electrode potentials are used together with potential-pH (Pourbaix) diagrams to determine the corrosion products that would be in equilibrium with the environment and the electrode surface.5
5.4 Electrode potentials are used in the estimation of corrosion rates by several methods. One example is by means of Tafel line extrapolation, see Practices G3 and G102. Polarization resistance measurements are also determined using electrode potential measurements, see Test Method G59 and Guide G96.
5.5 Corrosion potential measurements are used to determine whether metal surfaces are passive in the environment in question, see Test Method C876.
5.6 Corrosion potential measurements are used in the evaluation of alloys to determine their resistance or susceptibility to various forms of localized corrosion, see Test Methods F746, F2129, G61, and G150.
5.7 Corrosion potentials are used to determine the metallurgical condition of some aluminum alloys, see Test Method G69. Similar measurements have been used with hot dipped galvanized steel to determine their ability to cathodically polarize steel. See Appendix X2.
5.8 Corrosion potentials are used to evaluate aluminum and magnesium alloys as sacrificial anodes for underground and immersion cathodic protection application, see Test Method G97 and NACE TM0190–2012.
5.9 Corrosion potentials are used to evaluate the galvanic performance of alloy pairs for use in seawater and other conductive electrolytes, see Test Method F3044, Guide G71, and Guide G82.
5.10 Electrode potential measurements are used to establish cathodic protection levels to troubles......
如電極電位的定義所示,要測量金屬的電極電位,必須將該金屬與氫電極組成測量電池,然后用電位差計或其他測量儀器測出該電池的電動勢。氫電極在金屬電極電位測量中起比較電極的作用,電化學測量中將它稱為參比電極。由于氫電極制作和使用都較困難,在實際測量中,經(jīng)常采用比較方便的飽和甘汞電極、銀-氯化銀電極和銅...
?。?)在Mn+/M電極反應中,M叫做物質的還原態(tài)。Mn+叫做物質的氧化態(tài),物質的還原態(tài)和氧化態(tài)構成氧化還原電對。電對也常用符號來表示,例如Zn2+/Zn是一個電對,Cu(II)/Cu也是一個電對等?! 。?)在表中所列的標準電極電位的正、負數(shù)值,不因電極反應進行的方向而改變。例如,當電極反應按...
電極電位是表示某種離子或原子獲得電子而放還原的趨勢。如將某一金屬放進它的溶液中(規(guī)定溶液中金屬離子的濃度為lm),在25℃時,金屬電極與標準氫電極(電極電位為零)之間的電位差,叫做該金屬的標準電極電位。一些金屬、非金屬以及同一種金屬具有不同價態(tài)的離子的標準電極電位,這些數(shù)值都是與標準氫電極比較而得出...
標準電極電位是以標準氫原子作為參比電極,即氫的標準電極電位值定為0,與氫標準電極比較,電位較高的為正,電位較低者為負。如氫的標準電極電位H2←→H+ 為0.000V,鋅標準電極電位Zn ←→Zn2+ 為-0.762V,銅的標準電極電位Cu ←→Cu2+為+0.342V?! 〗饘俳谥缓性摻饘冫}...
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