Investigation on aging behavior and failure mechanism of blast-resistant polyurea coating in service environments

The influence of environmental factors on mechanical properties of blast-resistant functional polyurea coating is investigated in this study. Blast impact test is firstly conducted to assess performance of polyurea coatings. Then environmental aging tests, including natural exposure and solution immersion, are performed to simulate typical service conditions affecting polyurea specimens. Deformation and damage resistance of polyurea-coated plates are compared with those of uncoated aluminum alloy substrates after blast impact experiments. The changes in hardness, thickness, and tensile behaviors of polyurea specimens are recorded during different aging tests. Microscopic characteristics are examined to explain mechanisms underlying wave propagation and tensile fracture. Results indicate that polyurea enhances blast resistance owing to its excellent tensile performance and microporous structure; however, these mechanisms are adversely affected by environmental aging factors. For initial unaged polyurea, the front coating is inferior to the back coating due to an unfavorable wave impedance mismatch with substrate, and polyurea-coated plates are superior to uncoated plate with identical substrates thickness. During environmental aging tests, final observations of yellowing, swelling, softening, and embrittlement demonstrate degradations in properties that can negatively affect the blast resistance application of polyurea in service environments.