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Metal Finishing Services

Advantages of Black Oxide Coating

 

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Black Oxide Coating, also known as Chemical Blacking is a conversion coating in which a protective barrier is achieved through a chemical reaction between the ferrous metal and the oxidising salts used in the bath. It’s often used on small and intricate moving components in applications such as gear, hydraulic blocks and tool and machine components. There are a number of advantages that the process offers:

Minimal Dimensional Changes

Black Oxide Coating is not a deposit on top of the surface in the way that electro-plated finishes would be, instead it is a chemical oxidation of the surface. This means that the coating itself has virtually no thickness at all and will not build up on corners. The lack of dimensional impact is one of the reasons that it is a popular process for small and intricate components where tight tolerances need to be observed.

Aesthetic Finish

The nature of this process means that a component that has been chemically blacked will not have its finish chip,peel,flake or rub off. The only way in which to remove the surface treatment would be through mechanical or chemical means. The finish itself is a dark black colour (no patina or rainbow effect) and may be shiny or matte depending on the surface of the part. A polished component will retain its luster after Black Oxidising. Black Oxidising is often used as a mean of easy part identification and is a finish that reduces light glare in turn limiting the risk of eye fatigue or distraction in moving parts.

No Hydrogen Embrittlement

Components that are electro-plated or phosphated may require stress relieving in order to prevent problems with hydrogen embrittlement, but this is not the case with Black Oxide Coating. Even where parts are rusty or scaled and acid pickling is required any hydrogen will quickly dissipate after processing thus avoiding this issue.

Corrosion Resistance

Black Oxide Coating provides mild corrosion resistance but is often combined with Oils and Waxes this is often enhanced. One advantage in this process is that it won't exhibit ‘white corrosion’ as some electro-plated parts will over time. This makes it ideal for internal electronics applications as the small, white corrosive flecks are actually conductive in nature and may cause an electrical short.

About Us

Silchrome Plating offer a wide range of metal finishing processes including black oxide coating for carbon and stainless steels. We are fully ISO 9001 and ISO 14001 certified and carry out all processes from our modern facility in Leeds, West Yorkshire.

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  • The official logos for the ISOQAR and UKAS industry regulatory bodies.