Finishing Treatments: Phosphatizing

Superior Shot Peening & Coatings offers a phosphatizing finishing treatment to prepare metal or steel pieces for painting or coating, helping prevent corrosion.

Phosphatizing differs from traditional painting or coating because the surface of the metal is chemically changed to a new substance. This is important because the new coating will not chip or scratch, ensuring that the base material is not vulnerable to corrosion and wear.

Why Should You Use Our Phosphatizing Finishing Treatment?

Can service parts from small to very large (up to 35 feet in length on a double dip).
Offer both zinc and manganese phosphate coatings.
Saves costs by phosphatizing hidden parts, springs, and bearings vs. painting or plating.
Provide aesthetically-pleasing finishes: black, blue-black, blue-gray, non-reflective, non-metallic, non-conductive, and “velvety.”
Rush jobs are easily accommodated to keep your project on time.
Provide service on-site or in the field. (Contact us for the availability of our tanks.)

Technical Information

Parts are either bathed in the phosphatizing chemicals or the chemicals can be sprayed onto the metal using a system similar to a conventional pressure-washer. In either case, the solution applied to the metal is composed of four parts: detergents, metal phosphates (zinc or manganese-phosphate), phosphoric acid, or additional agents such as reaction catalysts or chemicals to tie up bi-products.

The detergents help clean and de-grease the surface of the metal.
The phosphoric acid provides for minor acid etching or picking to allow for better paint and lubrication adhesion.
The metal phosphates react with the surface of the part to form the corrosion-resistant phosphate coating.

First Reaction: Iron comes into contact with the phosphoric acid, causing acid pickling. Iron (Fe) is oxidized and hydrogen ions (H+) are separated from the phosphoric acid and reduced to form hydrogen gas (H2). Some of the oxidized iron sloughs off or dissolves, leaving the surface acid-etched.

Second Reaction: The zinc phosphates are deposited onto the substrate to form the conversion coating.