Phosphating is one of the most functional non-metallic treatments to prevent galling and for break-in lubrication. Phosphate treatments are usually applied to carbon steel, cast iron, and low-alloy steel. Phosphate treatments are formed during a process of chemical conversion. Steel or iron parts are placed in phosphoric acid allowing an acid and metal reaction to occur.
Both manganese and zinc phosphate coatings may be referred to as “Parkerizing Treatment” and “Parco Lubrite.” Both versions have multiple applications in military, firearms, aerospace, and oil and gas industries among others.
Manganese Phosphate Coatings
Manganese phosphate coating is applied to ferrous metals to prevent galling and for break-in lubrication. Usually used in conjunction with oils applied after phosphating for best results. In some applications, like zinc phosphate, it can be used as a base for organic finishes.
- Prevents galling
- Extended lubrication properties
- Corrosion resistance
- MIL-DTL-16232 type M Class I, II, III, IV
- Surface prep (blasting) and any subsequent coating done in house
- Normal turn time is three to five working days (unless other post coating processes are required)
- Expediting available when possible for an additional fee
Zinc Phosphate Coatings
Zinc phosphate coating is usually used as a base for other coatings, paints, oils and waxes, including use as primer for Chemical Agent Resistant Coating (CARC) painting. Its thickness is measured by coating weight—generally less than 100mg/m2.
- Corrosion resistance
- Improved paint and coatings adhesion
- TT-C-490, type I & III
- MIL-DTL-16232 type Z
- Surface preparation, phosphating and coating all available in-house to conform to certain MIL specifications for time between processes
- Normal turn time is three to five working days (unless other post coating processes are required)
- Expediting available when possible for an additional fee
More Information On Zinc Coatings
What is Zinc Phosphate Parkerizing?
Parkerizing is a process that applies a protective coating for a steel surface to prevent corrosion and wear. The process includes the application of a thin layer of a phosphate conversion coating, such as zinc, iron, or manganese. This chemical coating achieves corrosion resistance, lubrication, or used as a foundation for other applications such as paint.
The parkerizing process begins by submerging the desired part into a phosphoric acid chemical solution. This solution primarily contains the key ingredient of zinc or manganese with additional components such as copper, nitrates, or chlorates. Next, the solution is heated to 190–210 °F for 5-45 minutes. You should begin to see small hydrogen bubbles forming in the solution, once the bubbling stops the process is complete and you can remove the metal part.
The Parkerizing reaction equation for the metal-phosphate-solution is as follows:
2 Fe(s) + Fe3+ (aq) + 3 H2PO4− (aq) → 3 FePO4(s) + 3 H2 (g)
This process cannot be used on non-ferrous materials such as aluminum, copper, brass, stainless steel or any steel surface with large amounts of nickel.