Manganese Phosphate Coating
Manganese phosphating can be used for different purposes ;
- It is suitable in cold forming. With lubrication, phosphate-soap coatings extend tool life, permit faster drawing speeds, allow for maintenance of closer dimensional tolerances, and produce a smooth, glossy surface on the finished parts.
- Alone or in combination with rust-inhibiting oils, waxed, or other organic coatings, manganese phosphates are a low-cost alternative to electroplating.
- Oil absorptive manganese phosphate coatings on bearing surfaces permit rapid break-in of moving parts without scuffing or welding by preventing metal to metal contact, as the friable coating is easily crushed when a load is applied. Additionally, the oil held by the crystals improves the lubrication of the treated surface and imparts corrosion resistance.
Manganese phosphate absorbes and holds lubricants that's why used in piston and weapon industries. It makes easy the sliding of moving parts which are running in lubricant by reducing the friction between metal parts. This type of phosphate coatings have more stable structure than iron phosphate and also zinc phosphate under high presure and high temperature.
As it is essential in all phosphating methods, firstly, metal parts are degreased. After degreasing activation is needed to set up uniform crystals. Temperature, application time, concentration, free and total acid points are the parameters to be cared. The process generally works at 70-100ºC , %15-20 concentration and with 5-20 minute of immersion time. Manganese phosphate coatings can residue a coating 4-40 gr/m² on the surface. It cannot be used as under paint coverage because of its ability of high dense coating.
