Black oxide coating for machined metal parts

Black oxide, also referred to as blackening or blackening steel, is a surface finishing process that transforms the surface of steel or iron into a sleek black oxide coating. The process provides several benefits, including increased corrosion resistance and an attractive black finish. Here are the detailed processing steps:

1. Cleaning: The first step is to clean the surface of the metal. Any grease, oil, or other contaminants must be removed to ensure proper adhesion of the black oxide coating. This can be accomplished by using a degreasing solution or other cleaning agents.
2. Rinse: After cleaning, the metal is typically rinsed with water to ensure that all cleaning agents and contaminants are removed.
3. Activation: The next step is to activate the surface of the metal by dipping it in an acidic solution. This solution removes any remaining oxides and prepares the surface for the black oxide.
4. Black Oxide Solution: The black oxide solution is then applied to the metal. This solution typically contains a mixture of sodium hydroxide, sodium nitrite, and other chemicals that react with the metal to form a black oxide coating. The solution is heated to a specific temperature and then applied to the metal using a dip tank or spray system.
5. Rinse: After the black oxide solution has been applied, the metal is rinsed thoroughly with water to remove any excess chemicals.
6. Sealant: A sealant is then applied to the black oxide coating to protect it from corrosion and to enhance its appearance. This sealant is typically a type of oil or wax that is applied using a dip tank or spray system.
7. Drying: The final step in the black oxide process is drying the metal. The metal is typically dried using a hot air blower or by allowing it to air dry for a specific amount of time.

Black Oxide Coating Services for Ferrous Metals

The finish produced by black oxide is typically matte and uniform in color, but there are variations in the finish that can be achieved depending on the type of steel or iron being finished and the specific process used. Here are some of the most common types of surface finishes that can be achieved:

1. Matte Finish: A matte finish is the most common type of surface finish achieved. The black oxide coating produces a uniform, non-reflective surface that is ideal for applications where aesthetics and corrosion resistance are important.
2. Semi-Gloss Finish: A semi-gloss finish can be achieved by using a sealant on the black oxide coating that contains a gloss agent. This produces a slight sheen on the surface while still maintaining the black color.
3. High Gloss Finish: A high gloss finish can be achieved by applying a clear coat over the black oxide coating. This produces a high-gloss, reflective finish that is ideal for applications where a highly decorative finish is desired.
4. Colored Finish: A colored finish can be achieved by using a black oxide process that includes a colorant in the process. This produces a colored oxide coating that can vary from brown to black, depending on the specific colorant used.
5. Antique Finish: An antique finish can be achieved by using a black oxide process that includes a rusting agent. This produces a rust-colored oxide coating that gives the metal an aged, antique appearance.

Black oxide is a surface finishing process that is widely used in various industries to enhance the appearance and corrosion resistance of steel and iron products. The black oxide coating produced by the process provides a uniform, matte black finish that is ideal for applications where aesthetics and durability are important. It is commonly used in the automotive, aerospace, and firearms industries, where corrosion resistance is critical. The process is also used for decorative purposes, such as in jewelry and other metal art pieces.