Corrosion Behavior of Sacrificial Coatings on Grade 10.9 Fasteners for Multimetal Armor Applications.

摘要

This experiment examined the effect of accelerated corrosion testing and immersion testing on 13-mm-grade 10.9 bolts. A matrix containing chemical agent resistant coating (CARC) and bare Al 5059, as well as Rolled Homogeneous Armor (RHA) steel plates with CARC that are each bolted together with one bolt of each pretreatment system were subjected to GM9540P in an attempt to evaluate the corrosion prevention properties of each selected coating and pretreatment while simulating the practical applications of bolt-on armor. Five candidate finishes (zinc plating in accordance with the American Society for Testing and Materials ASTM)-B 633 with hexavalent chromium conversion coating as control were tested in replicate sets of assemblies. In the immersion phase of testing, each bath was heated to 75 F, and the salt solution was agitated in order to prevent stagnation and ensure equal heating. Testing was completed over 500 h, with visual and potential inspections at 1, 2, 4, 8, and 24 h, and every subsequent 24 h thereafter. Accelerated corrosion testing was programmed for 120 cycles GM9540 with inspection for corrosion creep at 20 cycle intervals. Corrosion creep in this experiment was defined visually as frosting for the onset of corrosion and red rust in the percentage of the fastener affected yielding separate observations. Each of the pretreatments are assessed and compared in terms of corrosion inhibition.