What does hydrogen embrittlement mean in the questions for the registered chemical engineer exam?

With so many experts, how is it that no one knows about them? :dizzy:

Metal corrosion caused by uneven oxygen distribution is known as differential aeration corrosion. The solid particles in soil include sand, silt, clay, and humus formed from the decomposition of plants. Between the soil particles, there are many curved micropores (also known as capillaries). Water and air in the soil can penetrate deep into the soil through these micropores. Apart from being combined with the components of the soil and adhering to the surface of the soil particles, some of the water in the soil can also flow within these micropores. Thus, the salts in the soil dissolve in these waters, forming an electrolyte solution; therefore, the higher the soil moisture, the greater the salt content, and the stronger the electrical conductivity of the soil. Furthermore, oxygen in the soil is partially dissolved in water and partially remains in the gaps between soil particles. The oxygen content in the soil is also closely related to the soil’s moisture level and structure: in dry sandy soil, oxygen can pass through easily, resulting in a higher oxygen content; in moist sandy soil, oxygen has difficulty passing through, leading to a lower oxygen content. ； In moist and dense clay, the passage of oxygen is even more difficult, hence the oxygen content is the lowest. Various metal pipes buried underground can suffer from differential aeration corrosion when they pass through soils with different structures and moisture levels. For example, if an iron pipe is partially buried in sand and partially in clay, the corrosion cell consists of an anode made of Fe – 2e⁻ → Fe²⁺ and a cathode made of O₂ + H₂O + 2e⁻ → 2OH⁻. It is easy to see that since the oxygen concentration in sand is higher than that in clay, the reduction reaction occurs more readily in the sand; thus, the electrode potential of iron in the sand is higher than that in the clay. As a result, the iron pipe in the clay acts as the anode of this differential aeration cell and is corroded. Similarly, metal components buried underground also experience differential aeration corrosion due to varying burial depths; corrosion typically occurs in the deeper parts, where oxygen has difficulty reaching, making those areas the anode of the differential aeration cell. In the case of horizontally placed metal pipes with larger diameters, corrosion usually occurs in the lower part of the pipes, again as a result of differential aeration.

It’s available directly on Baidu, and there’s also Baidu Baike

Hehe,,, thanks for the advice :)

Thank you for the advice. :victory: