Degradation Of Epoxy Wave Absorbing Materials In Different Environment Condition

Carbonyl iron/Epoxy(Fe/EP) coating and honeycomb structure radar absorbing materials(SRAM) are widely used in military and civil affair. The change of the service state and service life of epoxy, which act as adhesive and film former, will be crucial for the materials in different environment condition. The accelerated aging experiment has been studied using high vacuum instrument,parallel xenon lamp of XQ500,ozone generator,salt spray aging instrument to simulate the application environment. The service condition and aging mechanism have been investigated in the paper.The results show that mass loss rates of Fe/EP coating and SRAM were lower than 1% in 10-4Pa for 48 hours and were low enough to be used in high vacuum condition. Methyl and aliphatic ether bonds in the Epoxy fractured with ultraviolet irradiation, but carbonyl iron and carbon power absorb ultraviolet, lower the aging degree of the Fe/EP coating and SRAM compared with pure epoxy. The ultraviolet only affects the structure of epoxy on the surface, and has little effects on the wave absorbing properties.Fe/EP coating was cured with methyl tetrahydrophthalic anhydride. The results show that oxidation takes place on the surface and the epoxy is eroded away from the surface under ozone exposure. But all the effects is limited on the surface, and ozone have little effects on the bulk properties of the coating. The carbonyl iron delay the aging of Epoxy coating in the neutral salt spray environment for the hindrance of carbonyl iron to water, but accelerate the aging of coating in the acidic salt spray environment for the reaction of carbonyl iron with H+. Therefore the coating can not be used in acidic environment.The contents of C=O and C-O and methyl group increase after ozone exposure for SRAM. But the oxidation of epoxy is limited on the surface and the ozone have little effects on the absorption layer and has little effects on the wave absorbing properties.