MACRODISTRIBUTION AND MICRODISTRIBUTION IN ELECTRODEPOSITION OF CHROMIUM AND ITS ALLOYS FROM ELECTROLYTES BASED ON CHROMIC-ACID - MICRODISTRIBUTION AND THROWING POWER OF THE ELECTROLYTES

Distribution of electrodeposited chromium and its alloys (Cr-W, Cr-Mo, Cr-Ti, Cr-Zr) at the surface with a regular two-dimensional microprof ile is studied. Standard, self-regulating, supersulfate, and tetrachro mate electrolytes, as well as electrolytes for black-chromium plating and producing the Cr-Zr and Cr-Mo alloys are characterized by a virtua lly homogeneous microdistribution. Electrolytes for depositing the Cr- W and Cr-Ti alloys under certain conditions exhibit a considerable ant ileveling action, which points to diffusion control of the process rat e. The study led to the conclusion that formation and operation of the cathodic film under the conditions of a steady-state cathodic process are divorced from diffusion limitations intrinsic to the cathodic rea ction rates; whereas the thickness of the cathodic film (at least of i ts part that determines the chromium reduction rate) is small compared with the amplitude of the microprofiles investigated.