钝化是指材料变得“钝化”的过程,这意味着它受腐蚀等环境因素的影响较小。它涉及自发形成一层非常薄的非反应性表面。 电影 它起到屏障作用,保护主体材料免受进一步侵蚀。这种薄膜通常是几纳米厚的氧化物或氮化物层。

(图片仅供参考)
钝化是指材料变得“钝化”的过程,这意味着它受腐蚀等环境因素的影响较小。它涉及自发形成一层非常薄的非反应性表面。 电影 它起到屏障作用,保护主体材料免受进一步侵蚀。这种薄膜通常是几纳米厚的氧化物或氮化物层。
The mechanism of passivation is electrochemical. When a reactive metal like chromium, aluminum, or titanium is exposed to an oxidizing environment (like air or certain acids), its surface rapidly oxidizes. If the resulting metal oxide is stable, dense, non-porous, and well-adhered to the metal surface, it forms a protective passive layer. This layer is extremely thin, often only 1-3 nanometers, but it is sufficient to dramatically slow down the rate of corrosion by preventing direct contact between the metal and the corrosive environment.
这种被动膜的稳定性取决于环境,尤其是 pH 值和某些离子(如氯化物)的存在。例如,不锈钢上的氧化铬([latex]Cr_2O_3[/latex])层在许多环境中都非常有效,但局部会被氯离子分解,导致点状腐蚀。这种被动层的分解和重构是一个动态过程。如果薄膜受到机械划伤或损坏,暴露在外的金属通常会在几乎瞬间重新钝化,这种特性被称为自修复。.
Passivation can be a natural process or can be enhanced artificially through chemical treatments, such as dipping stainless steel in nitric or citric acid to remove free iron from the surface and encourage the formation of a more robust chromium-rich oxide layer. This process is distinct from applying a coating, as the passive layer is formed from the base metal itself.
钝化
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