Nitric acid passivation is the traditional method of removing free iron from the surface of stainless steel, titanium and other metals for corrosion prevention. As the legacy method of passivation, nitric acid on stainless steel offers the advantage of a proven, established process.

While nitric acid is commonly used as a passivating acid for stainless steel, citric acid is gaining in popularity as it is far less dangerous to handle, less toxic, and biodegradable, making disposal less of a challenge.

2020年12月7日 · Passivation can be defined as a metal finishing process that serves to prevent corrosion. For stainless steel, the process of passivation uses nitric acid to eliminate free iron from the surface. The chemical treatment that is done produces a protective layer of oxide.

2024年10月7日 · Choose the best passivation method for your stainless steel parts with Brulin. Learn about the pros and cons of nitric and citric acid options.

To the average machine shop operator the passivation of stainless steel means to merely pickle out the iron from the surface and increase the area of nickel on the surface. For this definition many shops are now using citric acid to "passivate" - but all it does it remove the iron from the surface. citric acid does NOT oxidize the nickel.

2019年7月11日 · Nitric acid passivation offers a range of options to customize the oxidizing potential of the acid to suit a specific grade of stainless steel. The various methods and types …

common method – Nitric acid. The most commonly used chemical method to passivate a stainless steel s rface is to apply nitric acid. Nitric acid is a strong mineral acid so it can quickly dissolve all iron compounds and other trace etals that are on the surface. Nitric acid is also a strong oxidizer so it can generate the chromiu

2007年5月3日 · Passivating Baths After thorough cleaning, the stainless steel part or component is ready for immersion in a passivating acid bath. In current practice, any one of three approaches can be used – nitric acid passivation, nitric acid with …

2003年10月1日 · In both cases, passivation is needed to maximize the natural corrosion resistance of the stainless steel. It can remove surface contamination, such as particles of iron …

Nitric acid passivation offers a range of options to customize the oxidizing potential of the acid to suit a specific grade of stainless steel. The various methods and types of nitric acid passivation include several heated options as well as options that include a sodium dichromate.

2025年1月19日 · The passivation process for titanium often involves using nitric acid or a combination of nitric and hydrofluoric acids. This treatment improves titanium’s resistance to rust, making it ideal for use in airplanes, medical devices, and chemical plants.

In stainless steel, the passivation process uses nitric acid or citric acid to remove free iron from the surface. The chemical treatment leads to a protective oxide layer, or passivation film, that is less likely to chemically react with air and cause corrosion.

2022年11月7日 · Historically, Nitric Acid has been the most common agent utilized in chemical passivation. Nitric acid is aggressive, attacking contaminants and trace elements such as free iron quickly, which speeds up the overall passivation process described above.

Nitric acid passivation is most useful in enhancing the corrosion resistance of freshly machined surfaces. The standard nitric acid passivating solution is made up and used as follows: 10 to 15 percent by volume of nitric acid (HNO3) in water.

2024年6月28日 · What is Nitric Acid Passivation? Nitric acid-based passivation is one of the most basic passivation techniques out there. Here, the stainless steel wire or sheet metal is dipped in a bath of oxidizing nitric acid.

Known as controlled corrosion, as the acid in the bath actually corrodes free surface iron, passivation is a widely used metal finishing process. It uses a nitric acid chemical treatment to create a protective oxide layer or passivation film.

ASTM (American Society for Testing and Materials) has issued a specification for stainless steel passivation that allows the use of citric acid solutions as an alternative to nitric acid solutions (ASTM A967-99).

When stainless steel is treated with nitric acid, two key reactions occur: First, nitric acid reacts with, for example, free iron particles on the surface, converting them into soluble iron ions (Fe²⁺ and Fe³⁺) that are removed from the surface. Fe + 4HNO 3 → Fe (NO 3) 3 + NO + 2H 2 O.

Nitric acid passivation involves using a solution of nitric acid to treat stainless steel surfaces. Here are some important aspects of nitric acid passivation: Strong Oxidizing Agent: Nitric acid is a powerful oxidizing agent that effectively removes free iron and other contaminants from the surface of stainless steel.

Nitric acid has been the preferred passivation system for the longest time due to QQ-P-35, the governmental specification for passivation until 2005 when it was replaced by ASTM A967 that allows the “old” nitric passivation and the “new” citric passivation.

Passivation employs specific chemical treatments - typically nitric or citric acid solutions - targeting free iron removal from stainless steel surfaces. This specialized process optimizes the formation of a protective chromium-rich oxide layer, significantly improving corrosion resistance. Key benefits include:

Passivation is a critical surface treatment process in custom manufacturing that enhances the durability and longevity of components, particularly those made from stainless steel and other corrosion-resistant metals. This guide explores the fundamentals, applications, and best practices of passivation in modern manufacturing. What is Passivation?