Examination of Alternative Pretreatments to Hexavalent Chromium Based DOD-P-15328D Wash Primer for MIL-A-46100D High Hard Steel Armor

摘要

Hexavalent Chromium based compounds with their associated health and environmental risks have necessitated reductions and even eliminations of their usage in U.S. Army weapon systems. These compounds are primarily associated with pretreatments and conversion coatings applied prior to primers and topcoats that make up the Chemical Agent Resistant Coating (CARC) coating system. Despite these hazards, for armor steels such as MIL-A-46100D high hard alloy, hexavalent chromium based DOD-P-15328D wash primer is still commonly used. This study explores the effectiveness of wash primer alternatives with respect to corrosion, adhesion, and susceptibility to Environmentally Assisted Cracking (EAC) issues. The alternatives studied were: spray based zinc phosphate in accordance with TT-C-490, grit blast only with no other pretreatment, and grit blast with a rust inhibiting sealer.