陰極保護(hù)中腐蝕的定義和發(fā)生

一、腐蝕的定義

?腐蝕是物質(zhì)與環(huán)境發(fā)生反應(yīng)，劣化變質(zhì)的過(guò)程。腐蝕如此普遍，以至于人們對(duì)其發(fā)生和發(fā)展熟視無(wú)睹，習(xí)以為常。

二、腐蝕的發(fā)生

?腐蝕是如何發(fā)生的呢?為什么一根完好的鋼管埋入土壤中，幾年后就會(huì)銹跡斑斑甚至穿孔報(bào)廢?要回答這些問(wèn)題，要從金屬的前生后世來(lái)解釋。以碳鋼為例，它們?cè)谧匀唤缰惺且澡F礦石的形態(tài)存在的。在人類把鐵礦石轉(zhuǎn)換成鐵金屬的過(guò)程中，施加了大量的熱量給金屬，也就是說(shuō)，人們所看到的金屬中，具有很高的能量。金屬所具有的能量隨金屬種類的不同而有所差異。例如黃金，在自然界中，它是以金屬單質(zhì)的形式存在，人類所要做的，只是把它從雜質(zhì)里分離出來(lái)，所以施加給它的能量就很低。具有能量的物質(zhì)都有將能量釋放、回歸自然低能的傾向。就好像將石頭放到山頂，它隨時(shí)會(huì)滾落到山下一樣。

??金屬為什么容易發(fā)生腐蝕?從熱力學(xué)觀點(diǎn)看，是因?yàn)榻饘偬幱诓环€(wěn)定狀態(tài)，有與周圍介質(zhì)發(fā)生作用轉(zhuǎn)變成金屬離子的傾向。金屬冶煉吸收能量，金屬腐蝕釋放能量。能量的差異是產(chǎn)生腐蝕反應(yīng)的推動(dòng)力，而腐蝕過(guò)程就是釋放能量的過(guò)程。

Definition and occurrence of corrosion in cathodic protection

1、 Definition of corrosion

Corrosion is a process in which substances react with the environment and deteriorate. Corrosion is so common that people turn a blind eye to its occurrence and development.

2、 Occurrence of corrosion

How does corrosion occur? Why is a good steel pipe buried in the soil rusty and even perforated after a few years? To answer these questions, we must explain them from the previous and future generations of metals. Take carbon steel as an example, they exist in the form of iron ore in nature. In the process of human converting iron ore into iron metal, a large amount of heat is applied to the metal, that is, the metal that people see has high energy. The energy of metal varies with the type of metal. For example, in nature, gold exists in the form of a single metal substance. All humans have to do is separate it from impurities, so the energy applied to it is very low. All substances with energy have a tendency to release energy and return to natural low energy. It's like putting a stone on the top of the mountain and it will roll down at any time.

Why are metals prone to corrosion? From the thermodynamic point of view, it is because the metal is in an unstable state and has a tendency to react with the surrounding medium to convert into metal ions. Metal smelting absorbs energy and metal corrosion releases energy. The difference of energy is the driving force of the corrosion reaction, and the corrosion process is the process of releasing energy.