The black oxide or blackening is a conversion coating for ferrous materials, stainless steel and copper based alloys. Hot baths of sodium hydroxide and nitrates at 141 degree C or 286 degree F are used to produce a surface oxide (magnetite Fe3O4). The process involves dipping the part into various tanks. The workpiece is usually “dipped” by automated part carriers for transportation between tanks. The tanks contain an alkaline cleaner, water, the blackening compound and the sealant (usually oil). Caustic soda produces surface oxidation that provides a barrier coating and mild corrosion protection when impregnated with oil or wax.
The advantages of blackening include:
- It can be done in large batches (small parts)
- No significant dimensional impact
- It is generally cheaper than similar corrosion protection systems
Parker Trutec’s MMI, Tennessee and Arkansas facilities offers world class black oxide services serving customers in the Midwest and Southern regions. We provide the convenience and flexibility your company needs to meet the demanding requirements of today’s manufacturing environment.