Process sheet · Zn/Mn phosphate

Heavy phosphate

A chemical conversion treatment that forms a non-metallic crystalline layer, mainly zinc and manganese phosphates, on steel. Unlike zinc coatings, its main purpose is to significantly reduce friction, prevent galling during break-in, and act as a porous, absorbent base that helps retain lubricating oils over time.

Typical applications
Engine and transmission components that operate under friction: pistons, rings, camshafts, cylinder liners, engine blocks, brake pads and similar bearing surfaces.
Cross-sectionZn/Mn PO₄ · 8–12 µm
Zinc and manganese phosphate8 to 12 µm · retains lubricant
Base steelCustomer part
Illustrative diagram, not to scaleµm
Technical data

Technical specifications

Base material
Steel
Coating thickness
8 to 12 µm
Appearance
Dark gray matte
Performance requirements
Lubricant retention and wear performance according to your customer's specification
Plating method
rack (hung) and barrel (bulk)
Part size
Parts under one meter in length
Minimum lot
50 kg
Coating thickness8–12 µm
Alkaline zinc
8–15
Zinc-nickel
8–15
Heavy phosphate
8–12

Coating thickness range for each process, in microns (µm). 1 µm is one thousandth of a millimeter.

FAQ

Quality control and FAQ

Does phosphate protect parts against rust?

On its own, it offers limited protection against environmental corrosion. Its resistance increases considerably when combined with the rust-inhibiting oil or lubricant that the part naturally retains in its porous structure.

Why is it called "heavy" phosphate?

Because it forms a denser, thicker layer (8 to 12 microns) than conventional light phosphates, which are used mainly as a pretreatment for paint adhesion.

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