Customers
Served
Parts
Manufactured
Countries
Shipped
Manufacturing
Partners
Black oxide is a chemical conversion coating applied to ferrous materials, typically steel or iron, through a controlled alkaline solution that reacts with the metal surface to form a black iron oxide layer (Fe₃O₄). This finish provides enhanced corrosion resistance, wear resistance, and reduced friction while maintaining the part's dimensional accuracy. The coating thickness is generally between 0.0001 to 0.0003 inches (0.0025 to 0.0076 mm), and it offers a matte, non-reflective appearance. Black oxide also improves surface hardness and provides minimal changes in surface roughness, often leaving values between 0.3 to 1.0 µm Ra. The process is cost-effective and environmentally friendly, as it uses no heavy metals and requires low energy. It also helps reduce the need for lubricants in mechanical assemblies, providing a smooth, rust-resistant surface. Black oxide is often used in automotive, aerospace, and industrial components, such as fasteners, gears, and shafts. It does not significantly affect the part's mechanical properties but can be sealed with oil or wax to further enhance corrosion resistance.
Primarily ferrous metals like steel andstainless steel.
Does not significantly change the base material's roughness.
Matte to satin black finish.
Widely used for decorative and low-reflection surfaces.
Very thin layer, typically <1 µm.
Retains original texture of the substrate.
A2 Tool steel, D2 Tool steel, A3 Tool Steel, O1 Tool Steel, S7 Tool Steel, H13 Tool Steel
932 Bearing Bronze , 954 Bearing Bronze, 544 Bearing Bronze
It improves appearance, corrosion resistance, wear resistance, and reduces light reflection while maintaining tight tolerances.
The quality of As Machined surfaces Common post-treatments include oil (glossy finish), wax (dull finish), and lacquer (quick-drying, protective layer).
Yes, but the coating may burn off in the weld area, requiring reapplication or additional post-processing.