When dealing with materials that are made from steel and iron, black oxide coating often comes up. It is generally applied to objects to keep them shielded from anything in the environment that might trigger unwanted changes and reactions.
The utilisation of black oxide coating is usually more favored by buyers than the other finishes as it could provide a rather more satisfactory finish at a lower price . It has 1 or 2 properties that make it the ideal choice for several commercial applications.
What's black oxide?
Black oxide is a coating material that is made by immersing parts into an alkaline aqueous salt solution at a temperature of approximately 285 degrees Fahrenheit. When the hot oxide bath and the iron react with each other, magnetite is produced and appears on the part surface. There's another process that involves the cold oxide bath, which results to the appearance of varied colors on different parts.
Typically, there are two categories of black oxide applied to steel and iron. They're the hot black oxide, often referred to as hot darkening, and room temperature blackening, sometimes called cold blacking.
In hot blackening, the ensuing product is a thin and corrosion-resistant iron oxide finish that's dark black. It is utilized in many varieties of gears, spark plugs, rifle barrels, sprockets and socket wrenches. The process sometimes uses mixes of wetting agents, sodium nitrate, caustic soda, sodium nitrite and stabilizers.
It is advisable that only folks with enough experience in performing hot blackening do this because it'd be highly perilous if amateurs try it. This is because of the fact that the black oxide bath is done at a temperature of approximately 290 degrees Fahrenheit, which is so much higher than water's boiling point. There is a bias that an explosion or eruption may occur.
In cold blackening, you can observe less care when performing the whole process because it is done at room temperature. There is a lower chance of getting yourself hurt or putting yourself at risk. But this sort of black oxide process is not considered a real one because what you do is just apply a copper selenium compound to a part. This compound isn't truly a good substitute for the real black oxide coating because it doesn't create the same quality of finish. It may be easily removed if you rub it off using your hands or a bit of material.
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