  The Cahn-Hilliard equation is related with a number of interesting physical
phenomena like the spinodal decomposition, phase separation and phase ordering
dynamics. On the other hand this equation is very stiff an the difficulty to
solve it numerically increases with the dimensionality and therefore, there are
several published numerical studies in one dimension (1D), dealing with
different approaches, and much fewer in two dimensions (2D). In three
dimensions (3D) there are very few publications, usually concentrate in some
specific result without the details of the used numerical scheme. We present
here a stable and fast conservative finite difference scheme to solve the
Cahn-Hilliard with two improvements: a splitting potential into a implicit and
explicit in time part and a the use of free boundary conditions. We show that
gradient stability is achieved in one, two and three dimensions with large time
marching steps than normal methods.
