Passivating

Passivating is a chemical conversion coating that inhibits corrosion in the base material.

Passivation of aluminum
Passivation of aluminum is a process that increases the corrosion resistance of the aluminum. A thin oxide layer is formed on the aluminum surface which protects the material from moisture and oxygen. Passivation of aluminum is a common process for electronics components or parts that shall be coated. In most passivation processes the thickness of the layer can be controlled by adjusting the time in the process bath. This is regulated in standards. The thinner layer is often used for parts that shall be coated with wet- or powder paint. It is also used for electronic components where a low contact resistance is required. The thicker layer has higher corrosion resistance and is therefore used for parts that will not be painted or were the corrosion demands are high.

There are different passivations for aluminum. Some commonly used are

ChromitAl – Surtec 650
Surtec 650 is a passivation process that contains trivalent chromium. Some advantages of SurTec 650 is its high corrosion resistance, increased adhesion for painting, that it is conductive and that it is environmental friendly.

E-clps 4600
This is a chromium free, cobalt based passivation method that has its biggest advantages for parts that need a conductive surface. This passivating method also gives an increased adhesion for painting.

Passivation of magnesium
Passivation of magnesium is a process where a thin oxide layer or a layer of a non-reactive material is formed on the surface of the part. Since magnesium is a highly reactive metal that reacts with water and oxygen, passivation is often necessary to improve the corrosion resistance. Passivating magnesium therefore contributed to a longer lifetime of the details. Passivation of magnesium can also improve adhesion for painting. There are multiple ways of protecting the surface of magnesium and passivation is one method. SurTec 650 is a commonly used passivation process for magnesium.

Passivation of stainless steel
Passivation of stainless steel improves the corrosion resistance of the material. By using a corrosive media, such as nitric acid, a thin oxide layer is formed on the surface. The oxide layer primarily consists of chromium oxide which is formed from the chromium in the material. This makes the surface of the stainless steel less prone to reaction and therefore more corrosion resistant. There are also other advantages to passivating stainless steel. The surface is better protected against contamination which makes it easier to keep clean and prolongs the lifetime of the parts. It is important to point out that the mechanical or physical characteristics is unaffected of the passivation process. There are a lot of different types of passivation processes for stainless steel and they are specified in applicable standards.

Passivation of zinc
Zinc is another metal that is possible to passivate, and it is often a part of the process when electroplating with zinc. When zinc corrodes, the product is white corrosions, and the passivation stalls this process. Passivating zinc also improves adhesion and increases the ability to paint on the metal. If corrosion resistance is an important factor, it is often possible to combine the passivation with a post-dip or a sealer. Passivation of zinc is available in different types and colors with different characteristics. Read more about this at our page for zinc plating

 

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Our passivating methods

E-Clps on aluminum

E-Clps on magnesium

E-Clps on die-cast zinc

SurTec 650 on aluminum

SurTec 650 on magnesium

Passivation of stainless steel

Passivation of zinc

Facts

Base material:
Aluminium, magnesium,
stainless steel, die-cast zinc

Standards

SurTec 650
MIL-DTL 5541

Stainless steel
ASTM A967