brass bolts - electrical connection

[johanzp]

Dear all,

we have brass bolts that should ensure proper electrical contact with a tinned ring clamped in between the bolts. The bolts are somewhat shielded from the outside environment with a cap but can nevertheless become wet by rain/condense etc.

Is this construction safe for electrical contact (10 years) or should we opt for another solution?

thanks
Johan

 

[EdStainless]

You need to seal them better. Silicon bronze bolts are used for electrical connections all of the time, but if the mating part corrodes then you are out of luck.
What voltage/power lever are you working with?

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Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[kenvlach]

No, due to some galvanic incompatibility, cannot expect 10 years use.

Best is to tin-plate the brass fasteners. Hot-dipped tin is preferable to electroplated.* Galvanic compatibility is shown in Table VI of (US) MIL-F-14072D FINISHES FOR GROUND BASED ELECTRONIC EQUIPMENT. For copper & copper-based alloys, Table III gives Finish M317, a tin coating >17.8 microns thick per MIL-T-10727, Type II (hot dipped). Probably, fasteners must be machined & coated by the mfr. to avoid thread tolerance problems.

(US) MIL-STD-889B DISSIMILAR METALS gives similar info but is more tedious to understand. To alleviate galvanic incompatibility, it recommends plating with the other metal of the couple.

*hot-dipped tin-coated brass fasteners may be difficult to find, so may use electroplated tin. Use a thicker grade, such as ASTM B545, Class D (15 microns).