Composition and Anticorrosion Behavior of Trivalent Chromium Passivation Film on Electroless Ni-P Coating

To control the environmental pollution caused by hexavalent chro-mium passivation of electroless Ni-P coating,a newly developed trivalent chromium passivation process was adopted to replace tra-ditional hexavalent chromium passivation process,generating ul-trathin passivation film atop electroless Ni-P coating. The effect of the trivalent Cr passivation film on the anticorrosion behavior of electroless Ni-P coating was investigated,and the composition ofthe passivation film was analyzed by means of X-ray photoelectron spectroscopy. Results indicate that the corrosion resistance of electroless Ni-P coating is greatly increased after trivalent Cr pas-sivation,and the resulting passivation film is mainly composed of C,O,Cr,Ni,N and P,where Cr mainly exists as Cr2O3 and Cr(OH)3.