The test on the galvanic currents

 
 
 
The   JB  is  made  by  two  slightly  different  Titanium alloys: BT-23 for the hemispheres and Ti 6 Al 4 grade 5 for the spacer.  Possible galvanic currentsbetween   the two   alloys  can be   created   in the   sea environment.  To measure this effect we have performed the following test:

- a couple of electrodes  composed by silver and the Ti BT23 alloy was located in a glass cells filled with sea water.

- the couple of electrodes was connected to a voltmeter on a 10 Kohms resistence.

-the reading of the meters was recorded for a 30 days period.

-the same procedure was applied in parallel to another couple of electrodes composed by silver and the other Ti 6 Al 4 alloy.

The plot shows the voltage reading as a function of time; the red triangles refer to the Ag/BT-23 couple while the blu diamonds refer to the Ag/Ti grade-5 couple. The expected voltage  between the two Ti alloys can be estimated from the difference of the red to the blue points: it is compatible to zero for most of the time indicating no evidence of galvanic currents.  The sharp spike in the Ti-grade 5 measurement might be due to a water refilling of the corresponding cell.