Accession Number:

ADA273709

Title:

Investigation of the MK83 Bomb Ablative Coating Failures

Descriptive Note:

Final rept.,

Corporate Author:

ARMY RESEARCH LAB WATERTOWN MA MATERIALS DIRECTORATE

Report Date:

1993-10-01

Pagination or Media Count:

17.0

Abstract:

This investigation determined the cause of an ablative coating adhesive failure on MK83 bombs that were stored for approximately five to seven years at the McAlester Army Ammunition Plant McAAP. An inspection of the contracting manufacturers facilities revealed white products on the bomb surfaces resulting from the zinc phosphate procedure. This affected the bonding of a subsequent epoxy primer. The handling of bombs prior to complete curing of the primer caused the primer to adhere to worktable surfaces. A lack of process control was observed at the McAAP where the polyester ablative was sprayed on top of the primer. The resin gun clogged for short periods causing a burst of resin to deposit onto the bomb while the catalyst gun continued to spray. In addition, the ratio of catalyst to resin was adjusted manually only when the coating was observed to be sagging because there were no automatic controls to regulate the ratio. The storage conditions at the McAAP were hot and humid during the summer and resulted in water condensation on the ablative coating surface. The palletized bombs were stored five high causing high stress on the ablative which lead to blistering. Spectroscopic characterization indicated that spots on die interior surface of the failed coatings were similar in composition to a viscous fluid that exuded from the ablative. Adhesion, Ablative, Coating, Epoxy, Polyester, Zinc phosphate.

Subject Categories:

  • Coatings, Colorants and Finishes
  • Miscellaneous Materials
  • Aerial Bombs

Distribution Statement:

APPROVED FOR PUBLIC RELEASE