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Citric Acid Passivation Services

Optimize Stainless Steel Before Coating

Maximize Performance of your Products with Citric Passivation before Coating

SilcoTek now offers citric acid passivation as a premium surface preparation step before applying our game-changing coatings. Passivation enhances the surface chemistry and inherent corrosion resistance of stainless steel by removing free iron that causes rouging, rust, and undesirable surface interactions. Semiconductor, biopharmaceutical, medical, and other industries where purity is paramount rely on citric acid passivation on stainless steel and other alloys. 

While passivation is not required before SilcoTek’s coating processes, surface cleanliness is critical to coating success. Passivating metal parts before coating creates an optimal coating surface and increases the corrosion resistance and overall performance of coated parts. SilcoTek offers Citric 2 passivation per ASTM A967 and other customer specifications. Combined with our cleanroom packaging services, SilcoTek is your trusted partner for highly value-added coated products. 

Passivation line

SilcoTek’s citric acid passivation services include: 

  • Citric 2 passivation per ASTM A967 and customer specifications 
  • Sonicated tanks with flow-through capability 
  • Forced air drying 
  • Robust quality assurance and control using copper sulfate test

Citric Passivation Data

ASTM A967 Standards

SilcoTek's ASTM A967 Citric 2 Passivation meets or exceeds SEMI F19 ultra high purity requirements. See chart below for SilcoTek's citric passivation line measured ratios.
Sample Cr/Fe Total CrOx/FeOx Estimated Oxide Thickness (nm)
1 1.9 3.2 2.4

 

 

Corrosion Performance

When paired with SilcoTek's Dursan coating technology, citric passivation has shown to improve the lifetime of the surface, reducing the corrosion rate by over half during the first month of exposure. Dursan corrosion passivation data

 

How Passivation Works

Passivation Graphic

 

Citric vs Nitric Passivation

 

Citric Passivation

 

Nitric Passivation

 
Safety Hazardous handling required Very safe to use as directed
Air Breathing Emits toxic and corrosive gases No toxic and corrosive gases emitted
Ease of Use Chemical handling safety equipment and extreme care required for most use Minimum chemical handling safety equipment required
Passivation Excellent passivation of most grades of stainless steel Excellent passivation of nearly all grades of stainless steel
Environment Environmentally hazardous Environmentally friendly
Cost 
  • Low cost raw material
  • High cost maintenance and disposal
  • High cost ventilation system for safe use
  
  • Higher cost chemistry
  • Lower maintenance, safety and waste disposal costs
  • Lower concentration of chemicals required
  • Lower overall cost to use
Passivation Process Duration 20 minutes to several hours 5-20 minutes typical
Process Temperature
  • Elevated temperature required for many grades
  • Nitric acid very dangerous at elevated temperatures
  
  • Room temperature use for many grades
  • Elevated temperature expedites the process
  • Safe without ventilation
Chemical Process Maintenance Regular solution monitoring required (titration) Regular solution monitoring required (specific gravity)
Iron Oxide Removal Slowly removes iron oxides Readily removes iron oxides
Equipment Long-term corrosive degradation of non-stainless steel metal or polymer-based equipment or components No corrosive degradation of equipment
Process Stability Must control time and temperature closely as danger of nitric oxide gas exists – proper ventilation required Less prone to time and temperature variation, no hazardous vapors
     
 

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