Beginning with a smooth ground aluminum blank with a relatively
thin layer of leveled Ni—P, circumferential
electropolishing / texturing is carried out to achieve a smooth oriented surface. A conductive
slurry is provided between the disc and a porous texturing tape which is in contact with a conducting plate or equivalent conductor. The disc serves as the
anode, and the conducting plate as the
cathode, while the
slurry, being conductive, functions as an
electrolyte. In the presence of current, a reverse
electroplating occurs so that the Ni—P dissolves to form Ni2+, or
nickel ions which are carried away by the conductive
slurry. The conductive slurry further supports or carries therein
abrasive material so that by moving the porous texturing tape past the disc surface, the texturing tape picks up the
abrasive material in the slurry and simultaneously with the reverse
electroplating, provides the desired
mechanical abrasion to achieve texturing of the disc surface. The
abrasive material comprises
diamond particles. The circumferential
electropolishing / texturing polish is achieved by
spinning the disc while applying the mechanical-chemical action through the slurry
system to the disc surface with
electric current passing through the electrically conducting interface during
processing.