Recent advances in industrial use of citric acid for stainless steel passivation

Nehrđajući čelici iz dana u dan postaju sve značajniji u suvremenoj proizvodnji. Područje njihove uporabe sve se više proširuje. Međutim, u određenim uvjetima koji oslabljuju svojstvo samoobnavljanja njihovog pasivnog sloja, oni postaju vrlo skloni koroziji, posebno lokalnim korozijskim oštećenjima. U uvodnom dijelu ovog rada definirani su nehrđajući čelici, njihova podjela i vrste korozijskih oštećenja. Drugi dio usmjeren je na pasivizaciju nehrđajućeg čelika, ponajviše otopinom limunske kiseline koja postaje sve važniji postupak u industriji. Proučena je najnovija literatura kojom se uspoređuju ekološki prihvatljiv i neškodljiv postupak čišćenja nehrđajućeg čelika limunskom kiselinom i najrasprostranjeniji postupak pasivizacije nitratnom kiselinom. Saznanja nedavnih istraživanja pokazuju da pasivizacija limunskom kiselinom ima značajne prednosti u odnosu na često primjenjivanu nitratnu kiselinu.Stainless steels, from day to day, become more and more important in modern manufacturing. The area of their use is increasingly expanding. However, in certain conditions that weaken the self-healing process of their passive layer, they become very prone to corrosion, especially lokalized corrosion damage. In the introductory part of this study, stainless steels, their classification and types of corrosion damage are defined. The second part focuses on the passivation of stainless steel, mostly by the citric acid solution, the process that becomes increasingly important in the industry. The latest literature has been studied and the comparison was made between the environmentally friendly and safe method of cleaning stainless steel with citric acid and the most widespread nitric acid passivation process. Recent research has shown that passivation with citric acid has significant advantages over the often applied nitric acid passivation