The Electrodeposition Of Zinc And Zinc Alloy Coatings On A3 Steel And Corrosion Resistance Performance Study Of Its

The direct and pulse electrodeposition was used to produce zinc and zinc alloy coatings on the surface of A3 steel substrate from various electrolytes. The steady-state polarization curves were measured by means of steady-state polarization techniques (the corroding agent used was a 3.5 wt. % sodium chloride solution) and the tests were carried out at a constant temperature of 30℃. The corrosion rate of the zinc and zinc alloy coatings was measured by using weight loss method after immersion in the artificial seawater in room temperature. The surface appearance and composition of zinc and zinc alloy coating were determined by using a number of surface analytical techniques, such as scanning electron microscopy (SEM) coupled with microprobe analysis (energy dispersive X-ray analysis: EDS),X-ray photoelectron spectroscopy (XPS). The preferred orientation of zinc deposits was studied by X-ray diffraction. The results show that the corrosion resistance of the zinc deposit was significantly improved after the chromate treatment. The addition of the REM to the bath does not change the preferred orientation of deposited Zn and affects texture coefficient of low-index crystallographic planes. It affects corrosion resistance. The granule of zinc alloy coating with rare earth Lanthanum additive was refined and more compact zinc alloy coating was obtained and the corrosion resistance of zinc alloy coating is improved remarkably. In order to examine spontaneity chromate performance of zinc alloy coatings, we do not add any addition agent in the bath.Many experimentals have been done in this paper and the regulation that grope for a zinc and zinc metal alloy electrodeposition, especially from the neutral aqueous solution zinc aluminum alloy being got. The content of the aluminum comes to a 0.8% in the alloy, bearing the eclipse function better. Cyclic voltammetry and AC impedance were also used to study corrosion resistance mechanism of coating and the basic component of equivalence electric circuit.