阴极保护中腐蚀的定义和发生
阴极保护中腐蚀的定义和发生
一、腐蚀的定义
腐蚀是物质与环境发生反应，劣化变质的过程。腐蚀如此普遍，以至于人们对其发生和发展熟视无睹，习以为常。
二、腐蚀的发生
腐蚀是如何发生的呢?为什么一根完好的钢管埋入土壤中，几年后就会锈迹斑斑甚至穿孔报废?要回答这些问题，要从金属的前生后世来解释。以碳钢为例，它们在自然界中是以铁矿石的形态存在的。在人类把铁矿石转换成铁金属的过程中，施加了大量的热量给金属，也就是说，人们所看到的金属中，具有很高的能量。金属所具有的能量随金属种类的不同而有所差异。例如黄金，在自然界中，它是以金属单质的形式存在，人类所要做的，只是把它从杂质里分离出来，所以施加给它的能量就很低。具有能量的物质都有将能量释放、回归自然低能的倾向。就好像将石头放到山顶，它随时会滚落到山下一样。
金属为什么容易发生腐蚀?从热力学观点看，是因为金属处于不稳定状态，有与周围介质发生作用转变成金属离子的倾向。金属冶炼吸收能量，金属腐蚀释放能量。能量的差异是产生腐蚀反应的推动力，而腐蚀过程就是释放能量的过程。
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.
