Solder Leads To Graphite For Conductivity Sensors

The conductors on motor brushes are held in with an conductive epoxy.

Clamp, screw or glue.

A difficulty arises if the newly-made connection is inadvetently immersed in the fluid. The shape as a result of the excess material forming the connection being in contact with the fluid as well as the graphite electrode will cause an increase in the flow of current compared to its being absent, and a corresponding error in the conductivity measurement derived from it, unless the characteristic of the cell can be evaluated and a new cell constant applied to allow for the change of shape.

the contacts will be encapsulated in epoxy, I wouldn't worry about having the contacts having exposure to any fluids.

Copper can be deposited on the graphite by electroplating. graphite surface can have various irregularity's to form nesting pockets for wires which can be soldered to the copper.

Apart from methods supplied by other members , you can screw thick copper wire with screw grooves in deep drilled graphite bar , you get such electrodes having solderable terminal already by manufacturer if you can find , they usually have conductive epoxy fillings for bonding ,or directly screwed just mentioned , well welcome to CR4 and best of luck.

are there vendors that could pre-metalize graphite for soldering or coat for soldering??

anyone?

Better than that. There are vendors that can sell complete type-tested and calibrated conductivity instruments for everyday use, thereby obviating any need for one to make one's own. Quotations may be had by engaging in telephone discussion with the process requirements to hand.