The nanocrystalline composite electrochemical coatings prepared with nickel matrix and PTFE particles were investigated. Nickel plating bath of low nickel ion concentration (0.75 M) with organic compounds and dispersed PTFE particles content was used for coatings electrodeposition. PTFE particles content was determined gravimetrically. The roughness of the nickel foils was evaluated using a profilograph. The microhardness of the deposited layers was measured using a Vickers' method at a load of 0.01 and 0.05 kG. Following dependencies were obtained:

R_a=0.44*C_p + 0.0065*D₁₁₁

HV_0.01=25.65/D₁₁₁^1/2

X-ray diffractometer with CuKα radiation was used to determine the preferred orientation, dimension of nickel [111] crystallites and microstress. The crystallographic structure of the composite coatings was investigated by TEM. Size of [111] nickel crystllites in the Ni-PTFE coatings varied from 11 to 39 nm. All coatings have approximately random orientation. Decreasing of the crystallite size in the nickel coating influenced on the increase of microstress. Voltammetric method and a three-electrode cell were used for examination of the samples of composite coatings in 0.5 M NaCl, pH 7. Results were used for calculation of the free corrosion potential and current. The corrosion resistance of all of the composite coatings was superior to that of the nickel coating. Non-conducting PTFE particles incorporated into a nickel coating also occur on its surface, which should affect the corrosive behaviour of composite coating. Following dependence was obtained:

P=26.3*P₁₁₁ + 1.5*D₁₁₁

The corrosion rate decreases with increasing of the preferred orientation (111) content and with increasing of the dimension of nickel [111] crystallites.

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