Coating with dense and fine particles containing fewer cracks and lower porosity shows more
improved protective properties due to limiting pathways between the environment and base metal. The
main aim of present research is to introduce an
innovative method that is called rephosphating to
achieve this morphology. The outstanding point of the
present investigation is to highlight the significant
effect of surface pretreatment by secondary grinding of
phosphated surface and then rephosphating of this
surface to obtain a coating with appropriate properties.
The SEM observations showed that this method has an
obvious influence on the formation of a very uniform
zinc phosphate coating on the plain carbon steel
compared with the traditional method of phosphating.
Furthermore, the protecting properties of phosphated
and rephosphated samples were described and compared using the neutral salt spray and the electrochemical polarization tests. The results showed that
rephosphating method had a beneficial effect on
improving the corrosion resistance. As well, improved
paint adhesion of rephosphated sample was observed
compared with that of the phosphated sample. Finally,
it was concluded that when rephosphating method can
be used to repair damaged phosphated areas, the
coating with more compact morphology and improved
properties can be achieved.