§ 16
How thick will the layer be, how long should the item hang, and how many amps should the rectifier give?
Answer: In a galvanic bath, the metal is deposited on the item by the current. How thick the layer becomes depends on the current density in A/dm², the time, the metal and the bath's current efficiency, i.e. what fraction of the current actually deposits metal. The rest becomes hydrogen. The calculator uses Faraday's law to work out the layer thickness from the time you enter and how long it takes to reach the thickness you need. It also shows what the rectifier should be set to for the entire suspension.
Faradays lov: masse m = I × t × M ÷ (n × F), F = 96.485 C/mol
Lagtykkelse (µm) = strømtæthed (A/dm²) × tid (s) × strømudbytte × M ÷ (n × ρ) × 100 ÷ 96.485
M ÷ (n × ρ): zink 65,38 ÷ (2 × 7,14) = 4,578 · nikkel 58,69 ÷ (2 × 8,91) = 3,293 · kobber 63,55 ÷ (2 × 8,96) = 3,546 · krom 52,00 ÷ (6 × 7,19) = 1,205
Control: nickel at 1 A/dm² and 100% efficiency gives approx. 12.3 µm per hour
Strøm på ensretteren (A) = strømtæthed × samlet areal (dm²)
| Symbol | Meaning | Unit |
|---|---|---|
| metal | Metal | — |
| stroemtaethed | Current density | A/dm² |
| tid | Time in bath | min |
| udbytte | Bath's current yield (from bath's datasheet) | % |
| areal | Total area in suspension | dm² |
| oensket | Required layer thickness | µm |
| = | Layer thickness after time | µm |
| = | Deposition rate | µm/min |
| = | Time to reach required layer thickness | min |
| = | Current on rectifier | A |
Does not apply when
The calculator's own default values inserted. The figures are calculated with exactly the formula the tool uses.
Substituted
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Når en ordre skal galvaniseres til en bestemt lagtykkelse, skal du vide, hvor længe emnerne skal hænge, og hvad ensretteren skal stilles til. Beregneren bruger Faradays lov med badets strømudbytte.
Et ophæng med beslag har 50 dm². De skal have 12 µm zink i et surt bad med 90 % udbytte ved 2 A/dm².
It means: Efter 30 minutter er laget 15.4 µm. Hastigheden er 0.51 µm/min, og de 12 µm nås efter 23 min. Ensretteren skal stå på 100 A.
Dele på i alt 20 dm² skal have 15 µm nikkel ved 4 A/dm² og 95 % udbytte.
It means: Efter 20 minutter er laget 15.6 µm. Den krævede tykkelse tager 19 min, og ensretteren skal give 80 A.
En aksel med 5 dm² skal have 25 µm hårdkrom. Badet kører 40 A/dm² og har kun 15 % udbytte.
It means: Efter en time er laget 27 µm, og de 25 µm tager 56 min. Ensretteren skal give 200 A.
Nikkel ved 1 A/dm² og 100 % udbytte lægger ca. 12 µm i timen.
Lagtykkelse ÷ tid skal give aflejringshastigheden.