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Black Oxide Overview

When you think of the typical metal finishing services a few select processes come right to mind; anodizing, gold plating, passivation just to name a few. However, there are a variety of metal finishing services that AOTCO can provide. One of those services is Black Oxide Conversion Coating.

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What is Black Oxide?

Black Oxide is not a typical plating process. Instead, it is a type of conversion coating where a chemical reaction occurs on the surface of the metal causing a very thin layer of oxide to form. Black Oxide conversions are carried out by submerging parts in a liquid alkaline and salt solution to introduce magnetite onto the surface of a substrate. Black Oxide leaves an extremely thin, corrosion resistant, and aesthetically desirable finish to its substrates.

aluminum finishes

Benefits of Black Oxide

Like any metal finishing process, Black Oxide provides its substrate with a range of desirable benefits and qualities. The most notable are listed below:

Aesthetically Pleasing Finish

Black Oxide is used more for its appearance than its function. The final appearance of your Black Oxide treated part is heavily based on the appearance of the base material. The black oxide process leaves the surface of a substrate dark, and non-reflective. This provides for a sleek, stealthy, and consistent finish for components. 

Controllable Reflexivity 

In addition, metals can be polished or abraded to increase or decrease reflectivity. Sometimes certain metals can reflect amounts of light so strong they can be distracting, even causing eye fatigue in extreme cases. The opposite can be true as well, with certain parts requiring reflective properties to resist solar radiation. 

If your end-goal includes light reflectivity the underlying material can be polished. Similarly, if your application calls for the surface to diffuse light, then you can opt for a matte/blasted finish to get the results you need.

No Dimensional Change

Unlike many other plating processes that we offer at AOTCO, Black Oxide chemical conversions produce no dimensional change to the components they are covering. Since there is no physical build up and only a chemical change at the substrates surface, there is no dimensional change. This is beneficial for industry parts that require specific dimensions or have complex geometries that cannot be altered during the electrofinishing process. 

Increased Lubricity

Oftentimes parts will require lubrication to be operational. Black Oxide coated parts can ensure easy lubrication. Black Oxide can also be post treated with oils or wax to further improve lubricity and provide anti-galling characteristics to its substrate. 

Easy Cleaning

Most metals are subject to corrosion due to exposure from water or other chemical solvents. This makes many metals rather difficult to clean without tarnishing it. Water and many cleaning solutions can cause non-desirable aesthetic changes to your components, but a black oxide chemical conversion eliminates these possibilities. With a surface chemically converted to be resistant to water and corrosion, components with a black oxide finish can be cleaned easily without risk of tarnish or erosion. 

Improved Resistance 

Aside from the aesthetic benefits of black oxide, it can also greatly improve the longevity of a part by improving its resistance. The chemical conversion of the substrate’s surface causes it to become less reactive, and therefore more resistant to corrosion. It also slightly increases the physical strength of the substrate, giving it greater resistance to wear and abrasions. 

What Black Oxide Specs does AOTCO Follow?

Oftentimes different clients will require us to follow certain procedural guidelines, each specific to a certain field/industry. These guidelines are referred to as specs, and there are ones for each of our metal finishing processes. 

At AOTCO, we abide by the following specs for our Black Oxide Chemical Conversion Process:

  • MIL-C-13924
  • MIL-DTL-13924

For a full list of all of the specs we follow at AOTCO please visit our Plating Specs page.


Do You Need Black Oxide?

Aside from Black Oxide, AOTCO also offers other black finishes such as Black Anodize, Black Nickel, and Black Ebonol.

Each of these finishes are suitable for a wide variety of applications. For example, Black Nickel tends to absorb light better while Black Anodize is more wear resistant. If you are unsure, or just curious about the different black metal finishes we provide, then it may be worth calling before placing an order.

In Conclusion

At AOTCO, we have been providing consistent and quality metal finishing services, including black oxide, since 1975. With a team of dedicated engineers and metal finishers, we are confident in our ability to aid in your next plating project. If you have any questions about our black oxide process, or any other metal finishing inquiries, feel free to contact us at 1-888-275-0880!


Looking for Specs?

Learn more about the specifications AOTCO offers, including NADCAP-accredited and RoHS-compliant ones.
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