The aim is to build up a fine-grained phosphate layer and to avoid creating phosphate layers with large grains. This means that great care is required right from the selection of cleaning products and processes during the preparatory processing steps. Maintenance of working conditions during phosphating (parameters such as temperature, concentration, etc.) is also an essential factor.
The requirement for generating the finest possible crystalline phosphate layers means that crystal sizes need to be determined. Important roles in the improvement of application engineering properties are played by, amongst others, the pore space and crystal size of the phase content of a phosphate layer, as well as roughness and pickling scars. Crystal sizes are therefore specified in some specific company standards to improve the sliding properties.
When using one of our optimised products, crystal thicknesses are generated with 95 % being smaller than 5 µm. This product also displays uniform distribution of the crystals and high density. The very fine crystalline layers are dark grey to mostly black. Preferred for improvement of sliding properties. Thickness layers from 2 µm can be produced. The basic requirement is of course compliance with the necessary general process parameters.