Blacken parts and bearings with cold black oxide

Advantages of Chemical Blackening for Bearings and other Moving Parts

Chemically blackening moving parts and bearings offers practical advantages.

The cold chemical black coating forms a protective and lubricating layer for steel parts. This can be applied with Verzinkshop Black Oxide or Black Oxide Ultra. During the chemical process, the surface layer of the treated parts changes into a thin mixed iron oxide layer (1 to 2 micrometers) containing FeO, Fe2O3 and Fe3O4. Because this finish is not a real coating, the dimensions of the bearing remain virtually unchanged. The black appearance comes from the mixed iron oxides in the conversion layer.

Chemical blackening is often used for corrosion protection. Due to the thin and porous black oxide layer, this protection is mainly achieved by applying a suitable water-repellent oil-based sealer, which is retained in the pores of the black oxide layer. The effectiveness of this protection therefore depends on proper maintenance.

There are complete kits available to make bearings black directly: Verzinkshop Black Oxide Kit or the Verzinkshop Black Oxide Ultra Kit

Benefits of a Chemical Black Finish on Bearings

Chemically blackened bearings have a number of important characteristics.

1. Improved break-in and wear characteristics
2. Better protection against adhesive scuffs
3. Protection against environmental influences

The conversion layer provides higher wear resistance, resulting in better break-in properties and shorter bearing break-in times. This reduces wear during break-in, leading to longer bearing life. The porous structure also helps to better hold lubricant on the functional surfaces, especially in critical break-in and start-up phases.

Bearings operating under low load or with rapid changes in speed can suffer from adhesive stroke, leading to wear and damage. This often happens when there is insufficient lubrication or when an unsuitable lubricant is used. The chemical black finish here can serve as a protective layer that slows down wear and damage. In the event of short-term contact between steel and steel, due to an interruption of the lubricant film, the risk of cold welding and other damage is significantly reduced.

In addition to the other benefits, the chemical black finish also provides protection against environmental influences. In combination with a suitable sealer, such as Verzinkshop DeepSeal Metal Sealer, it improves corrosion protection and forms a barrier against harmful substances, such as hydrogen and aggressive ingredients in lubricants. This helps to improve the effectiveness of protection in gear systems.