Given there is conflicting information floating around concerning the relative hardness of nickel vs palladium - perhaps more attention should be directed to this detail. Apparently all of the direct comparisons agree that nickel is indeed softer than palladium unless it has been work hardened (as when it is drawn into wire). It is indeed drawn into wire to make mesh, normally so it should be harder than Pd... end of story.
Catch-22 when drawn nickel is to be woven to make the wire mesh then it is almost always first annealed as it is too hard to weave, otherwise. When annealed it is softer. Opps. Nickel does not re-harden after a heat treatment and quench so the normal mesh should, on paper, be too soft for burnishing with Pd. In short - it should NOT be possible to use a palladium rod to coat nickel mesh unless the nickel has been work hardened, which it has been in order to make wire - BUT when wire is woven into mesh it is most often but not always annealed to make it softer. So the bottom line is that nickel wire must hardened and not annealed in order to coat it and yet this detail is not mentioned... yet there is more. One exception to this hardness issue would be if the rod being used to apply the Pd was made from J-M Type A palladium, which is considerably softer than pure. I double checked and nowhere could I find the composition of the palladium rod. There are several relevant papers and I may have missed it. Does anyone know? BTW - Some of this detail about Type A goes back a decade or more to when BARC in India discovered that the alloy used in palladium filters (which is Type A) was testing dramatically better at excess heat than pure Pd. Later in France IIRC, Type A was used for the hero results. Normally it would be specified by anyone following P&F protocol. Prior to BARC, it was thought that Silver prevents full deuterium loading, but there is scant evidence for that, and anyway - in the new Mizuno technique, high loading is to be avoided so it makes sense that the rod would be Type A or else the nickel was not annealed before weaving. Given the cost of palladium these days, I suspect it could be a rod that Mizuno has owned for some time and he may not have been fully aware that it was Type A alloy. Hopefully Jed will have the answer to this ...
