Phosphate Coatings

Phosphate Coatings became popular during the First & Second World War as it was discovered that treating metal surfaces to modify their properties for various purposes including corrosion protection, improving paint adhesion, and improved lubricity. A war-time shortage of tin resulted in phosphate as an option to replace tin plated steel.  Phosphate coatings in the original rust-proofing application probably reached an all-time record high during the war particularly in the UK and USA with vast quantities of armament parts owning their durability in service to this treatment.  Popularity carried over in post war years as newer applications of phosphate coatings appeared. With few fundamental advancement in the phosphate process since this time, steady advance in techniques have accelerated popularity among metal manufacturers.  

Both Zinc & Manganese Phosphate coating are typically a stand alone coating or used as a base for paint or other top coat finishes. Phosphate offers a greatly enhanced bonding on ferrous alloy in addition to being an underlying base coat for added corrosion protection. As a stand alone coating, phosphate provides excellent base for holding rust preventatives, lubricants, etc.  A friable crystalline structure is formed which is an excellent anti-galling selection for break in application for shafts, gears, and various moving assemblies.

BOI performs both immersion zinc & manganese phosphate coating processes certifying to various aerospace & military specifications:
MIL-DTL-16232 Type M & Type Z, Class 1, 2, & 3
AMS 2480 (Zinc Phosphate)  AMS 2481 (Manganese Phosphate)

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