THE NUCLEATION AND GROWTH OF GRAPHITE - THE MODIFICATION OF CAST-IRON

It is considered that all forms of graphite, precipitating from a meta llic solution, must evolve from a basic hexagonal ring structure, grow ing into an open monolayer sheet. Subsequent growth of this precursor can lead to multi-layer sheets-flake graphite, to rolled or wrapped co ncentric shells-spheroidal graphite, or, possibly, to saturated fuller ene units. The molecular attachment kinetics which might favor these a lternatives are briefly discussed and compared with experimental evide nce. Spheroidal graphite is the preferred morphology in a dean melt, f lake graphite is an impurity modified form and growth to form fulleren es is presently unpredictable, but is considered to be improbable.