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Estimate the MRR (in cc/sec) of an alloy containing 18% cobalt, 62% nickel and 20% chromium during ECM with current of 500 ampere. The density of the alloy is 8.28 g/cc. The following data is available.
Metal Gram atomic weight Valency Cobalt 58.93 2 Nickel 58.71 2 Chromium 51.99 6
Assume Faraday's constant is 96500 coulombs/ mole.
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- 1.24 × 10–3 CC/sec.
- 1.24 × 10–2 CC/sec.
- 24 × 10–2 CC/sec.
- 1.24 × 10–4 CC/sec.
Correct Option: B
Given data:
Current (I) = 500 cump.
Density (f) = 8.28 g/cc.
| MRR = | |
| ρZF |
where, A = atomic weight Z = Valency
F = Faraday’ s constant= 96500
 |  | = | + | + | |||||
| A | equivalent | A1 | A2 | A3 |
| = | + | = | = 5.03 × 10–2 | |||
| 58.93 | 58.71 | 51.99 |
| MRR = | |
| 8.28 × 5.03 × 10–2 × 96500 |
= 1.24 × 10–2 CC/sec.
