Patent ID: 7575694
Filing Date: 2009-08-18
Classification: C23F,F01D

Abstract:
1. A process of selectively stripping a metallic coating on an external surface of a substrate without attacking an internal surface defined by an internal passage within the substrate, the process comprising the steps of: depositing within the internal passage a molten wax of a thermally-decomposable polyethylene wax having a melting temperature above 75° C.; allowing the molten wax to cool and solidify to form a solid mask of the polyethylene wax within the internal passage and mask the internal surface defined by the internal passage; treating the substrate with an aqueous solution at a temperature below the melting temperature of the polyethylene wax, the aqueous solution containing an acid having the formula H heating the substrate to melt the polyethylene wax and remove a portion thereof and then further heating the substrate to thermally decompose a remaining portion of the polyethylene wax without producing a hazardous byproduct.