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