TECHNOLOGY FOR MAKING A LAMINATED ANTICORROSIVE PROTECTION BY NANOMETRIC ELECTROCHEMICAL DEPOSITION IN NON-HOMOGENEOUS LAYER PACKETS

摘要

The invention relates to a process for anticorrosion protection of metal parts by electrochemical deposition of nanometric Zn or Zn alloy layers packets, the coating process being intended to be applied on metal parts exploited in corrosive media. According to the invention, the process comprises a stage of preparing the metal surfaces by chemical cleaning , electrochemical cleaning , acid pickling, activation, neutralization and multiple washing, a stage of deposition of a layer of Zn or Zn alloyed with Ni, Fe, Co, Sn or with other elements, by electrodeposition in an acid or alkaline zinc coating electrolyte, followed by a second electrodeposition in the same zinc coating electrolyte which additionally comprises nanoparticles in suspension, in the said sequence or in a reversed one, the pair of layers being possibly followed by a sequence in which one or both layers as mentioned above are alternated in comparison with the layers of the initial pair, where the nanoparticles may be particles of titanium dioxide TiO, aluminium trioxide AlO, silicon dioxide SiOor combinations thereof, after which the so treated part is washed, chromate coated and dried.