Cameron - If we start with the 30um average layer as being the way to achieve maximum strength for a given mix, it occurred to me to wonder what size single particle would achieve this in close packing. My calculation suggests a diameter of 160um. I took 74.4% of the space taken up by the particles, the remainder epoxy. This, spread round the particles gives an average layer of 15um round each one, the two layers giving the required thickness.
If you could confirm my calculation, would this suggest that the presence of particles smaller than this, inserting themselves in place of the epoxy, is going to reduce the average layer thickness, and hence the strength for this consideration only ?
I can see that the smaller particle would add strength from a point of view of increasing the "locking up" of larger particles, but how do the two factors compare in affecting the final performance ?
Having spent some of my sleepless hours trying to work that out in my head, it seems to me now that it would greatly ease the general discussion if the relative effects of each of the many variables being considered could be listed in order of importance to the final strength.
A rough "order of magnitude" figure would also help people decide at what stage they could start experimenting with a set up to achieve their own design.
What think thou ?
John
It's like doing jigsaw puzzles in the dark.
Enjoy today's problems, for tomorrow's may be worse.