If the residue is sodium or potassium salts it is likely that it came from the black oxide process.
Black oxide coating problems.
We use a high temperature black oxide to finish a number of different tools a couple of these tools have joints with a tight fit.
Curtis you could confirm the source of the white residue by carefully scraping some of it off the parts and analyzing it.
Solving iron copper and zinc contamination problems.
To achieve maximal corrosion resistance the black oxide must be impregnated with oil or wax.
This means that the black oxide is not deposited on the surface of the substrate like nickel or zinc electroplating.
A problem solving guide for black oxide coatings that s the direction this article is taking.
The finish should be oily black.
The tools are thoroughly rinsed and soaked in hot water an extended period of time.
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Avoiding excessive sludge and chemical buildup.
Aluminum and copper in ultra blak 400 baths or other black oxide solutions.
Achieving a cleaner deeper black finish.
We find that 30 40 of the tools show salt bleed out at the joints.
The black oxide process is a chemical conversion coating.
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Control buildup of sludge red iron oxide zinc.
Many more letters about black oxide and room temperature blackening can be found by searching the site.
The reaction between the iron of the ferrous alloy and the hot oxide bath produces a magnitite fe3 o4 on the actual surface of the part.
It is used to add mild corrosion resistance for appearance and to minimize light reflection.
Putting a tick in that checkbox the coating should also be moderately corrosion resistant.
Only the inspector s pen is wavering.
One of its advantages over other coatings is.
As advantageous as this supplementary feature undoubtedly is black oxide failure does occur so we need to stay abreast of the common problems incurred by this oxidizing process.
Instead the black oxide coating is produced by a chemical reaction between the iron on the surface of the ferrous metal and the oxidizing salts present in the black oxide.
Black oxide hi temp application.
Where to get it done.
Assessing process variables as with any high end engineering process numerous variables are at work during a black oxide coating sequence.
Black oxide or blackening is a conversion coating for ferrous materials stainless steel copper and copper based alloys zinc powdered metals and silver solder.
Black oxide is a conversion coating formed by a chemical reaction produced when parts are immersed in the alkaline aqueous salt solution operated at approximately 285 degrees f.
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