Deposition Rates

Among plating baths used commercially to deposit common metals (other than precious metals), cadmium cyanide baths are high in both throwing and covering power; only alkaline tin and cyanide copper have greater throwing power. Based on Haring-Blum cell measurements, the throwing power of cadmium cyanide baths is rated between 40 and 45%, with a distance ratio of 5. Therefore, the distance between the anode and the work is not critical, although as the distance is increased, current density and efficiency decrease, and current distribution is altered.

Table 3 lists the times required to plate cadmium deposits from 3 to 18 ^m (120 to 720 ^in.) thick. These times are predicated on 90% cathode efficiency.

Table 3 Time for plating cadmium to a given thickness at various current densities

Data based on 90% cathode efficiency, in a cyanide bath

Table 3 Time for plating cadmium to a given thickness at various current densities

Data based on 90% cathode efficiency, in a cyanide bath

Thickness of plate

Plating time in minutes at current density specified

fini

^in.

54 A/m2 (5 A/ft2)

110 A/m2 (10 A/ft2)

160 A/m2 (15 A/ft2)

215 A/m2 (20 A/ft2)

270 A/m2 (25 A/ft2)

325 A/m2 (30 A/ft2)

3

120

13.0

6.5

4.3

3.2

2.6

2.2

5

200

26.0

13.0

8.6

6.4

5.2

4.4

8

320

39.0

19.5

13.9

9.6

7.8

6.6

10

400

52.0

26.0

18.2

12.8

10.4

8.8

13

520

65.0

32.5

22.5

16.0

13.0

11.0

15

600

78.0

39.0

25.8

19.2

15.6

13.2

18

720

91.0

45.5

30.4

22.4

18.2

15.4

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