The silicon carbide is in polymer form also very large molecules, but in long, spaghetti-like chains. Tiny spheres form as silicon carbide polymers cross-link with carbon macromolecules. Silicon carbide polymers also surround the spheres. As the mixture gets hotter, carbon and silicon atoms continue to connect. The small spheres coalesce into larger ones.
Impurities boil off.
The silicon is bound to carbon atoms on the spheres surfaces atoms that would otherwise be vulnerable to oxidation. Thus the crystals protect the carbon from burning. Yet they re too small to interfere with the carbon s heat-absorbing properties. High-resolution imaging instruments are needed to characterize such materials at the nanoscale level. Lafdi uses a transmission electron microscope to discern the molecular arrangement of the ceramic crystals.