What effects does passivation treatment have on the performance of medical decontaminated stainless

The core function of passivation treatment is to form a uniform and dense Cr₂O₃ passivation film on the surface of the pipe, which has a decisive positive impact on its corrosion resistance, biological safety and operational stability. The details are as follows: 

Significantly enhance corrosion resistance

The passivation film can isolate the pipe material substrate from the external environment (body fluids, disinfectants, medicinal solutions, etc.), preventing the erosion of stainless steel by chloride ions, acidic / alkaline substances.

Effectively inhibit pitting corrosion, intergranular corrosion and crevice corrosion, especially in medical chlorine-containing disinfectants (such as iodophor), and physiological saline environments, the corrosion resistance life can be increased by 3-5 times.

After the welding part undergoes passivation treatment, it can repair the natural oxide film damaged during the welding process, avoiding the weld seam from becoming a corrosion weak point. 

2. Ensure biological safety

The passive film is dense and free of pores, which can reduce the release of metal ions such as nickel and chromium. The release of nickel ions can be controlled below 0.5 μg/cm²/week, meeting the ISO 10993-15 standard.

Prevent the reaction of metal ions with human body fluids and blood, reduce the risk of sensitization and cytotoxicity, and ensure the tissue compatibility when in long-term contact with the human body.

The passive film itself is non-toxic and non-irritating, does not react chemically with drugs, and does not affect the stability of the drug solution. 

3. Optimize surface performance

After passivation treatment, the surface color is uniform and consistent, without oxide spots, and the surface becomes smoother and cleaner, reducing the attachment sites for bacteria and dirt.

Strengthen the stability of surface cleanliness. Even after repeated sterilization with high-temperature and high-pressure, ethylene oxide, etc., the surface still remains free of peeling and detachment, avoiding the contamination of the medical environment by the detachment of pollutants.

The surface roughness of the pipe material is not changed (it needs to be combined with degreasing process), ensuring that it meets the requirements of medical Ra ≤ 0.8 μm (implants ≤ 0.2 μm). 

4. Does not affect the mechanical properties of the substrate

The thickness of the passivation film is only 5-10nm, which will not alter the core mechanical indicators such as tensile strength, yield strength, elongation, etc. of the pipe material.

It does not affect the welding performance and cold forming performance of the pipe material, and can still maintain good processing compatibility during subsequent medical equipment assembly.

It has no significant impact on the hardness of the pipe material, will not lead to an increase in brittleness, and ensures the structural stability during use. 

5. Extended service life and reduced maintenance costs

The protective effect of the passivation film can reduce the failure probability of the pipe material due to corrosion, especially in medical scenarios where the equipment undergoes repeated sterilization and is in prolonged contact with corrosive media, resulting in a significant extension of the service life.

Reducing the frequency of maintenance and replacement due to corrosion, lowering the long-term usage cost of medical equipment, and avoiding medical risks caused by the corrosion and damage of the pipe material.