Chemical Conversion (Passivation) and Chemical Oxidation

Chemical Conversion (Passivation) - is a coating that is produced by electrochemical or chemical reaction of metals, giving a superficial layer which contains the metal compound.

Passivation is the use of a light coat of a protective material, such as metal oxide, to create a shell against corrosion. It offers economical protection against corrosion and a surface suitable for painting. It also preserves electric conductivity, in contrast to anodizing which produces coatings that are non-conductive. Chromate and Cr-free conversion coating is a common way of passivating not only aluminum, but also zinccadmiumcoppersilvermagnesium, and tin alloys.

Chemical Oxidation is one of the chemical conversion coatings. With the use of chemical substances when applied to the metal surfaces, this starts chemical reaction which creates oxidation on the metal's surface - a stable anti-rust oxide film. Commonly used in aluminum and aluminum alloy, copper and copper alloy, carbon steel and so on.

Aluminum and aluminum alloys are generally passivated with sodium carbonate solution of chromate (鉻酸鹽), silicate (矽酸鹽), phosphate (磷酸鹽); copper and copper alloy with caustic soda solution containing oxidant; while carbon steel is caustic soda solution with nitrate.

Trivalent chromium (Cr+3)
三價鉻 (鉻酸鹽皮膜處理)

■ ROHS/WEEE compliant:YES

■ Benefits: 

1. Cost is better than Cr+6, because the toxic is less

2. Improved corrosion resistance

3. Lower concentration levels result in less chromium waste

4. Painting adhesionability

Cr-free passivation
無鉻鈍化/非鉻皮膜

■ ROHS/WEEE compliant:YES

 

■ Benefits: 

1. Corrosion resistant

2. Painting adhesionability

Hexavalent chromium (Cr+6)
六價鉻

■ ROHS/WEEE compliant:NO

 

■ Benefits: 

1. Corrosion resistant

2. Painting adhesionability

Phosphate passivation 
磷酸鹽鈍化

■ ROHS/WEEE compliant:YES

 

■ Benefits: 

1. Corrosion resistant

2. Painting adhersionability

Passivation for stainless steel
不鏽鋼鈍化

■ ROHS/WEEE compliant:YES

 

■ Benefits: 

Improved stainless steel corrosion protection without plating

Black oxidation for stainless steel
不鏽鋼黑化

■ ROHS/WEEE compliant:YES

 

■ Benefits: 

1. Corrosion resistant

2. Painting adhersionability

Electro Polishing
電解拋光
Electro Polishing
電解拋光

■ ROHS/WEEE compliant:YES

 

■ Benefits: 

Reduces or eliminates stressed and disturbed layers caused by heat treating, decarburization, microscopic scratches, tool marks, grinding checks, cutting and abrasive finishing, thus greatly improving fatigue life.

Characteristics

​*** For detailed selection list of Plating and Coating processes, please refer to Plating & Coating Table

  • Facebook
Regulus Electronics Taiwan