The thickness and hardness of the chromium film electrodeposited on even a plane surface are never uniform, but vary from place to place of the cathode plate.
Regarding this variation, the author carried out a series of experiments of chromium plating under the following conditions:
1. Bath composition: CrO
3 250g., H
2SO
4 2.5g., distilled water 1 liter.
2. Bath temperature: 50±1°C.
3. Size of electrode: 35mm×10mm×2mm.
4. Plating time: Changing from 1 to 2hrs.
5. Current density: Changing from 10 to 45A/dm
2.
6. Distance of electrodes: Changing from 1 to 5cm.
The result: The thickness and hardness of the circumferential part of the cathode plate were from 2 to 3 times as thick as, and 8.5 per cent harder than those of the central part respectively.
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