INVESTIGATION OF THE ELECTROCHEMICAL CORROSION RESISTANCE OF HYBRID Ni-SiC-FLUOROPOLYMER COMPOSITE COATINGS

ABSTRACT

In the present study, an attempt has been made to use dispersed ceramic and polymer particles to produce nickel hybrid composite coatings and to evaluate the effect of these particles on the electrochemical corrosion of these coatings. A nickel-plating bath with low concentration of nickel ions (45 g/dm ³ ), brightening agent, surfactants, and dispersed particles of SiC with PTFE or CFx were used for deposition of the hybrid composite electrochemical coatings. Scanning electron microscopy (SEM) was used to examine the deposit morphology with EDX (LEO 435VPi and LEO 1530) in order to determine the composition of nanocrystalline composite coatings on the same surfaces. The weight percentage of the dispersed phase in the coatings was determined gravimetrically. A Siemens D500 Diffractometer with Si[Li] radiation was used to examine texture and grain size. A voltammetric method was used for examination of the samples of hybrid composite coatings. After surface degreasing with acetone in an ultrasonic bath, the samples were transferred to a three-electrode cell. Platinum foil served as the counter electrode. The reference electrode was a silver-silver chloride electrode (SCE) during tests in 0.5 M NaCl, while for the measurements performed in 0.1 M H₂SO₄, a sulphate electrode was used via an electrolytic bridge with a Haber-Luggin capillary. The voltammetric measurements were carried out using computer-controlled ATLAS 98. The sweep rate was 1 mV/s after stabilization of the open-circuit potential at a temperature of ^{20± 2 ○} C. Results were used for calculation of the free corrosion potential and current.

ACKNOWLEDGMENTS

This work was performed under the auspices of the State Committee for Scientific Research though Grant No. 7 T08C 01020.