being the Bob from Windstuff's page, i know a bit about castiron resin mixes
a couple of thoughts if i may
- the permeability is not good, better than air but much less than laminate silicon steel.
- the stuff is very high in electrical resistance so eddy currents should be small.
turns out it is ok for single magnet rotor where you need an opposing steel to return the flux from the magnets, just ok,, easier than making a sloted laminate backplate, but not near as good, now having said that.
i don't know of anyone that has worked with this stuff in a dual rotor air core alternator, it might be that there is some potential in that the stuff would provide some directionalilty across the airgap without most of the attendant cogging issues that laminate steel presents.
if it weren't so damn costly in time and money one could use the polymer cast iron
to make up the centers of the coils, much like coil formers. wind the coils on them
screw them down to a wood backing (bottom of the form) and then imbed the coils into the common resin mix.
there likely would be some improvment in output from the aircore alternator using this method, perhaps more than what is given up due to cogging.
again there would be some cogging but only a fraction of that presented by laminate steel.
if someone wants to go that route, a good source of cast iron chip is under a brake lathe,, just use a magnet to winnow out the good iron from the dirt.
when it comes to mixing with resin, mix the resin with its hardener as usual
and then fold it into a plastic container that has the needed amount of castiron chip in it waiting. use no more than is needed to make it a wet mix, very stiff and almost dry works very well.
there are a jillion other uses for this stuff as well, it makes a very good cold cast iron, and with the addition of a steel frame armature (much like rebar in concrete) very strong casting can be made.
bob g