Blackened metal may go by a number of terms, such as blackening, black oxide, oxidising, and more. These terms refer to the process of forming a black iron oxide on the surface of ferrous metals, or metals known to rust and corrode. This chemical conversion coating process first invented for common use in tooling and machinery came with a number of benefits.
The fact that it is a chemical conversion coating means it cannot be deposited on the surface of nickel, zinc electroplating, or any other type of substrate. The black oxide coating is produced by the chemical reaction between the iron on the surface of the ferrous metal and the oxidising salts found in the black oxide solution. After a chemical reaction involving a number of steps, the result is the formation of black iron oxide coated on the surface of the metal.
Often after the black oxide finish, providers apply a supplementary post-treatment used to increase the corrosion protection properties of the blackening process. After the chemical blackening of steel, for example, those using it should expect to see a dramatic reduction in rust and corrosion over time. In addition, the metals literally appear blackened, which can be an aesthetic appeal.
As previously stated, the biggest benefit associated with metal blackening is the corrosion protection. Depending on the process performed by the hired company, blackening done right can give corrosion resistance equivalent to 144 hours of salt spray exposure. Other applications may also provide extended shelf life for parts stored prior to use or to prepare parts for further surface treatment, such as painting. In short, buyers enjoy much more use and longer lifespan from their tools and machinery components.
At most, blackening should add no more than 10 millionths of a centimetre to the dimension of the metal. For all intents and purposes, the dimensions do not change at all, as they otherwise would when painted or plated. For this reason, even critical-size parts can undergo blackening without risk of losing functionality.
If post-treated with oil, not only will the metal remain more corrosion resistant, but the oil itself should result in smoother running, mating parts. For buyers in need of multiple working machinery components and tools, such a benefit can improve efficiency across the board while adding lifespan to each critical part. When many factories and other businesses utilise parts thousands of times a day, such a benefit can add to a company’s bottom line.
The final, lustrous black appearance of metal blackened this way should provide a certain level of aesthetic appeal and a “quality” appearance at a cost-effective price. Harder metals tend also to have glossier finishes, while softer parts appear to have matte finishes. When clients and business partners regularly come into contact with certain components of a project, appearances can improve impressions.
Although companies want functionality over aesthetics every single time, this is one process designed to afford a company both. For this reason and the many other benefits associated with this process, blackened metal may yet replace other options in the future.