Corrosion Immersion Testing of 13-mm-Diameter Grade-10.9 Bolts for Bolt- on Armor

摘要

This experiment examined the performance of selected coatings and pretreatments on 13-mm grade-10.9 bolts immersed in a 5% NaCl solution in an attempt to evaluate the corrosion prevention properties of each selected coating and pretreatment relevant to those selected for bolt-on armor. Five candidate finishes as well as zinc plating in accordance with ASTM B 633 with hexavalent chromium conversion coating as control were tested. Each bath was heated to 75 deg. F, and the salt solution was agitated in order to prevent stagnation and ensure equal heating. Testing was completed over 500 h, with visual inspections and open circuit potential measurements at 1, 2, 4, 8, and 24 h, and once every 24 h following. In this experiment, corrosion creep was defined visually as frosting for the onset of corrosion and red rust in the percentage of the fastener affected, each yielding separate observations.