Zinc Phosphate TT-C-490 Type I and Per Mil-DTL-16232 Type Z Class 1,2,3, and 4.
In most operations where the corrosion resistance of finished workpieces must be especially high, conversion coatings are applied using zinc phosphate . This approach is widely used in the automotive industry and in certain sectors of the appliance and electronics industries. Similarly, zinc phosphating is often specified by the armed services, especially for equipment that may be exposed to severe environments. Moreover, many operations using electrocoating or powder coatings, particularly when a one-coat finish will be exposed to the weather, pretreat workpieces with zinc phosphate.
Iron Phosphate TT-C-490 Type II
Iron phosphating is the most preferred conversion coating method for indoor equipments due to its advantage of low first investment cost and unit prices of the chemicals. Iron phosphate coating chemicals are easy to use products that can be used by wiping, spraying or dipping for the metal surfaces do not require high corrosion resistance.
Manganese Phosphate A-A-59267 and Mil-DTL-16232 Type M
Manganese phosphate coating has the highest hardness and superior corrosion and wear resistances of general phosphate coatings.
Manganese phosphating is extensively employed to improve the sliding properties of engine, gear, and power transmission systems. The use of manganese phosphated coatings for improved corrosion resistance can be found in virtually all branches of the metal working-industry. Typical examples mentioned here include motor vehicle components in brake and clutch assemblies, engine components, leaf or coil springs, drill bits, screws, nuts and bolts, washers, anti-vibration washers, tools, magnet cores, casting interiors and many other small items.
Manganese phosphate coatings for conferment of good corrosion resistance, whether a post-treatment such as oil application is to be used or not, are invariably applied by the immersion method.