Passivation Service Supplier In China
Passivation is a chemical cleaning process that removes free iron and other contaminants from the surface of stainless steel, enhancing its natural ability to resist corrosion. This is not a coating, but a treatment that allows the formation of a clean, passive, and highly corrosion-resistant chromium-oxide layer. As a specialized supplier in China for high-performance components, Celerity Precision offers expert passivation services that conform to industry standards like ASTM A967 and AMS 2700, ensuring your stainless steel parts achieve their maximum corrosion resistance and service life.
To unlock the full corrosion-resistant potential of your stainless steel components, trust Celerity Precision, your expert passivation partner.
Your Passivation Finish Manufacturer
At Celerity Precision, we are a manufacturer that treats passivation as a critical final step in the production of stainless steel components. Our in-house chemical treatment line is dedicated to performing this process with scientific rigor. We go beyond simple immersion; our process involves a multi-stage cleaning and degreasing to remove all machining oils and residues, followed by a controlled immersion in a nitric or citric acid bath. We carefully monitor the acid concentration, temperature, and time to effectively remove surface contaminants without etching or damaging the part itself. This meticulous control is essential for creating a robust passive layer.
By managing both the precision CNC machining and the passivation process, we ensure complete control over the part’s integrity from start to finish. We understand that a part cannot be properly passivated if it is not properly cleaned, and our integrated workflow guarantees this. This is especially critical for our clients in the medical, aerospace, and food processing industries, where surface purity is paramount. As your direct manufacturing partner, we provide certification for our passivation process, giving you full traceability and the confidence that your parts are truly “stainless.”
Ensure your components are free from contaminants and fully protected. Upload your stainless steel project to Celerity Precision for a quote on a complete manufacturing and passivation solution.
Passivation: Technical Specifications
| Feature | Description |
| Surface Roughness (Ra) | No Impact. Passivation is a chemical cleaning process that does not alter the microfinish of the surface. The Ra value of the part before and after passivation will be virtually identical. |
| Applicable Materials | Exclusively for Stainless Steel alloys (e.g., 303, 304, 316, 17-4 PH, etc.). |
| Cosmetic Availability | Not Applicable / Functional. The process does not change the appearance of the metal, though a thoroughly cleaned and passivated part may appear slightly brighter or shinier than a non-treated part. Its purpose is purely for performance and cleanliness. |
| Visual Appearance | No visible change. The part will look exactly as it did after machining, just exceptionally clean. There is no coating or color change. The process creates an invisible, passive oxide layer that is only a few molecules thick. |
Advantages of Passivation Surface Finish
Maximizes Corrosion Resistance
Removes free iron, the primary catalyst for rust, allowing stainless steel to achieve its inherent, maximum resistance to corrosion.
No Dimensional Change
As a surface cleaning treatment with no material buildup or removal, it has zero impact on the final dimensions of tight-tolerance parts.
Improves Surface Cleanliness
The process removes all residual oils, dirt, and metallic contaminants from the machining process, making it ideal for medical and food-grade applications.
Eliminates Contamination Risk
Ensures that no iron particles from the part can contaminate other materials or processes in a sensitive environment.
Extends Product Lifespan
By preventing the onset of corrosion, passivation significantly extends the reliable service life of stainless steel components.
Uniform and Comprehensive Treatment
The chemical bath treats all surfaces of the part, including internal bores, threads, and complex geometries, with equal effectiveness.
Passivation Design Considerations
Specify the Standard
It is best practice to specify the passivation standard on your drawing (e.g., "Passivate per ASTM A967" or "Citric Passivate per AMS 2700") to ensure compliance.
Material Choice Matters
While all stainless steels can be passivated, certain free-machining grades (like 303) require specific bath chemistries to prevent etching. Our expertise ensures the correct process is used.
No Cosmetic Enhancement
Do not specify passivation if you are looking for a cosmetic improvement like a mirror polish. For that, electropolishing is the appropriate choice.
Welded Assemblies
Weldments can be passivated, but the area must be thoroughly cleaned of all weld scale and discoloration prior to the process for it to be effective.
FAQ
I thought stainless steel doesn't rust. Why does it need passivation?
During machining, microscopic particles of “free iron” from cutting tools can get embedded in the surface. These particles will rust, making it look like the stainless steel itself is rusting. Passivation removes these particles.
Is passivation a coating?
No, it is a cleaning process. It does not add any material to the surface; it only removes contaminants.
Will passivation change the look of my parts?
No. A passivated part will look identical to a freshly machined and cleaned part. Any change in appearance is usually due to the intensive cleaning process, not the passivation itself.
How is passivation different from electropolishing?
Passivation is a chemical cleaning process for performance. Electropolishing is an electrochemical process that removes material to smooth and polish the surface, which also passivates it as a secondary benefit. Choose electropolishing for a mirror finish.
Does passivation add to the dimensions of my part?
No, there is absolutely no dimensional change.
Can you passivate carbon steel or aluminum?
No, the process is specifically designed to enhance the chromium-oxide layer unique to stainless steels.
What is the difference between nitric and citric acid passivation?
Nitric acid is the traditional method. Citric acid is a more modern, environmentally friendly alternative that is equally effective and is the standard for most medical and food-grade applications. We offer both.
How do I know if my parts have been properly passivated?
We perform quality tests, such as a copper sulfate test or a high-humidity test, to verify that all free iron has been removed and the surface is passive. We can provide a Certificate of Conformance for our process.
Can parts with brazed or soldered joints be passivated?
It is generally not recommended, as the passivation acids can attack the filler materials used in brazing and soldering.
How should I specify passivation on my drawing?
The simplest effective note is “Passivate.” A better, more professional note is to specify the standard, for example, “Passivate per ASTM A967 using citric acid.”