Frequently Asked Questions and Fact Sheet
Passivation: (for practice of cleaning, descaling of stainless steel material)
Is defined as the chemical treatment of stainless steel with a mild oxidant, such as nitric acid solution for the purpose of the removal of free iron or other foreign matter, but is not generally effective in removal of heat tint or oxide scale on stainless. Passivation may also include the removal of sulfides from the surface of the metal for the purpose of maximizing corrosion resistance.
What is Black Oxide?
Black Oxide, blackening, oxidizing, oxiding, black passivating, gun bluing . . . these terms all refer to the process of forming a black iron oxide on the surface of ferrous metals.
The black oxide process is a chemical conversion coating. This means that the black oxide is not deposited on the surface of the substrate like nickel or zinc electroplating. 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 solution. These oxidizing salts include penetrates, catalysts, activators and proprietary additives which all take part in the chemical reaction. The result of this chemical reaction is the formation of black iron oxide, magnetite (Fe3O4), on the surface of the metal being coated.Black oxide has a range of unique properties and benefitsthat can be applied to a variety of industries.
Applying a supplementary post treatment after the black oxide finish is commonly used to increase the corrosion protection properties of black oxide coatings. Alone, black oxide offers only a very mild corrosion resistance. A properly applied post treatment, allowing full absorption of the supplementary coating into the pores of the black oxide finish, enhances the corrosion protection to the metal, while producing a deeper black appearance. An appropriate post treatment also increases the resistance to abrasion of the black oxide where break-in of mating parts is required.
Oil post treatments are frequently used after black oxide coating. The oil can be either water-soluble or water displacing and can be controlled so that a fairly heavy oil film is left on the part or so that the part is virtually dry to the touch. Of course, less oil means less corrosion protection. A clear wax or acrylic may also be used as an alternative, dry to the touch post treatment, where absolutely no oil film is desired.
Post Treatments for Improved Corrosion Resistance
· Water Soluble Oil Light (dry to the touch)
· Water Soluble Oil Regular
· Water Displacing Oil Regular
· Water Displacing Oil Heavy
· Rust Inhibitor
· Water Soluble Wax
· Clear Lacquer
What are the Advantages and Benefits of BLACK OXIDE?
Dimensional Stability:
Black Oxide adds about 5 to 10 millionths of an inch to the dimension of a part. It also penetrates to an approximate depth of 5 to 10 millionths of an inch.
Improved Lubricity:
Oil post-treatment not only protects against corrosion, but the oil itself results in smoother running mating parts.
Anti-Galling:
Where break-in of mating parts is necessary, the anti-galling surface lets the outer lubricating layer be sacrificed during initial contact while work-hardened surfaces are formed.
Decorative Finish:
The resulting lustrous black finish adds visual appeal and a “quality” image at a very low cost. Harder parts (40 Rockwell and above) tend to have glossier finishes. Softer parts tend to have matte finishes.
Reduce Light Glare:
Moving machine parts, hand tools and surgical instruments coated with Black Oxide reflect less light and reduce eye fatigue when used under bright lights.
Industries that use Black Oxide:
Athletic & Sports
Defense
Fastener
Machined Tools
Recreational
Stamping
Utility Hand Tools
Medical
Frequently Asked Questions:
Question: Does Black Oxide come in other colors?
Answer: No. Black Oxide is a natural reaction of the metal with the Black Oxide bath. This finish can vary from shiny parts with a tight smooth and/or hardened surface to matte parts with a porous non-hardened surface. An oil post-treatment will help give a shiny finish. A wax or rust inhibitor will make the finish matte.
Question: What does dry to the touch mean?
Answer: This is a subjective term that means something different to everyone. In the industry it describes the degree of oil on the surface of the part. An oil finish can give a feel of no oil, light oil or oily.
Question: Can Stainless Steel be Black Oxided?
Answer: Yes. Stainless steel can be blackened to Mil-C-13924 Class 4
Question: Can Copper/Brass/or Bronze be Black Oxided?
Answer: Yes. All three materials can be blackened to Mil F-495.
Question: Will the Black Oxide coating crack or fracture if the part is bent or twisted after Black Oxide?
Answer: No. Black Oxide is an integral formed surface of the metal that allows for forming of the part.
Question: Can Zinc or Chrome plated parts be Black Oxided?
Answer: No. Black Oxide will not blacken over zinc or chrome or any other plating finishes. However, we do have the capabilities of stripping zinc plating and would therefore be able to plate parts that are stripped. This only applies to the zinc plated parts.
Question: Can blackened parts be re-plated?
Answer: Yes. This can be achieved by stripping the plating first and then re-applying the Black Oxide finish.
Question: Can Aluminum be black oxided?
Answer: No, anodizing is often times confused with black oxide. Aluminum will actually dissolve in a black oxide bath.
Some of our customers are:
Solar Turbines, Goodrich Aerostructures, Autosplice, General Dynamics, Rockwell Collins, Honeywell,
Asigma, Alturdyne, VQ Orthocare, Vertech and many more….