Influence of the Hydrochloric Acid Content on Spray Etching
Spring 1994
Influence of the Hydrochloric Acid Content on Spray Etching of Stainless Steel with Ferric Chloride Solutions
According to Brady [1) there is a fundamental difference
between natural highly concentrated FeCl3 solutions
and those additionally acidified with HCr. In a
“natural” solution the link onto the trivalent ferric ion
occurs mostly in the shape of an octahedron. The addition
of acid produces a chain consisting by turns of tetrahedral
and octahedral formations that are knitted
together by Cl-ions. This structural shifting can
perhaps influence the etch rate as well as the etched
surface topography.
It is also known that hydrochloric acid reduces the
inner friction and thus the viscosity of highly concentrated
FeCI; solutions [2).
A. Visser and M. Junker, University of Bremen
