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Date of Publication:2022-10-09

Journal:稀土

Volume:35

Issue:5

Page Number:62-68

ISSN No.:1004-0277

Abstract:This paper indicates the optimum techniques parameters of rare earth
   cerium conversion coating on the aluminum silicon alloy surface by
   orthogonal as follows:Ce(NO_3)_3:14g/L;KMnO_4:1. 5 g/L;K_2 S_2 O_8:1. 0
   g/L;NaF:0. 8 g/L;pH value of solution:2. 0,immersing 60 min at room
   temperature. Results of the SEM,EDS and XRD show that Ce- Mn conversion
   coating,which is close to the matrix,is composed of a matrix film and
   particles of different sizes adhesive on the film;the coating thickness
   is about 10~ 5 mum,consisting essentially of oxide or hydroxide of Ce
   and Mn. The coating is amorphous structure,with the same direction,can
   inhibit the generation of micro- battery electrolyte. The polarization
   curve,electrochemical impedance spectroscope(EIS) and soak test results
   have the following findings:1) the Ce- Mn conversion coating corrosion
   potential increases 210 mV;2) the corrosion current density decreases to
   1/10 compared with the previous;3) it has higher layer resistance and
   charge transfer resistance,the lower layer capacitor and electric double
   layer capacitor,higher dielectric constant. Ce- Mn conversion coating is
   more compact and has less surface defect and uniformly covers the
   surface of aluminum silicon alloy. It has a good protective effect on
   flue gas condensate.

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