雷达吸波涂层腐蚀失效对雷达隐身性能的影响

Effect of Corrosion Failure of Radar Absorbing Coating on Radar Stealth Performance

目的 研究腐蚀失效后的吸波涂层与雷达隐身性能的变化规律。方法 制备7块吸波涂层样品,分别进行0、24、48、96、240、480、840 h的中性盐雾试验。通过X射线能谱仪和扫描电子显微镜、电化学工作站分别对试验后的样品组成成分和微观形貌、电化学阻抗谱进行表征。利用矢量网络分析仪对盐雾试验后的样品在8~18 GHz频率范围内的雷达波反射率进行测试。结果 吸波涂层在试验96、240 h后出现局部小范围点蚀现象,480、840h时出现大面积点蚀现象。同时,吸收剂形貌也发生改变,涂层氧含量增加,说明涂层中吸收剂被渗入的腐蚀介质腐蚀氧化。通过等效电路图拟合交流阻抗谱数据结果,认为样品腐蚀失效经历了3个阶段,840 h盐雾试验后,样品膜值较试验前原始样品(0 h)已下降69.7%,说明涂层防护性能得到极大破坏。0h样品雷达波反射率均值为-4.27,4dB带宽实现了70.07%,840h样品反射率均值为-4.71,4 dB带宽达到了87.53%,整个试验过程反射率测试结果的均值相差不到0.5 dB,说明雷达隐身性能并没有下降。结论 在一定时间阶段内,雷达吸波涂层中吸收剂被氧化腐蚀,并不会导致雷达隐身性能下降。

For equipment serving in harsh tropical marine seawater/atmospheric corrosive environments,studying the variation law of stealth performance of radar absorbing coatings in corrosive environment,and revealing the mechanism of coating corrosion failure on radar stealth performance are of great benefit to extend the service life of absorbing coatings,ensure stable and reliable absorbing performance,formulate scientific and reasonable maintenance plans,and reduce maintenance costs.The work aims to study the variation law of absorbing coatings after corrosion failure and the stealth performance of radar.Firstly,7 Q235 steel plates with a size of 120 mm×50 mm×2 mm were prepared.After sandblasting,a strontium chrome yellow primer layer with a thickness of(30±2)μm was sprayed.After cured at 80 ℃ for half an hour,the radar absorbing coating with a thickness of(0.58±0.05)mm was sprayed.After cured at 80 ℃ for 2 h,the 7 parallel samples were completed.Then,neutral salt spray test was carried out for 0 h(original samples not subject to salt spray test),24 h,48 h,96 h,240 h,480 h and 840 h,and the composition and microstructure of the samples after the test were characterized with X-ray energy dispersive spectrometer and scanning electron microscope.Gmary Reference 3000 electrochemical workstation was used to perform electrochemical AC impedance spectroscopy test on the samples after salt spray test,and the equivalent circuit diagram was introduced to describe and fit the AC impedance data to further analyze the failure mechanism of the coating.The Agilent E8363C vector network analyzer was used to connect the terminal open circuit test fixture,and the 8-18 GHz radar wave reflectivity test was carried out on the samples after the test.After 96 h and 240 h salt spray test,there was visible local small-scale pitting corrosion on the absorbing coating,and after 480 h and 840 h,the corrosion phenomenon was obviously serious and large-area pitting corrosion occurred.At the same time,the morphology of the absorbent also changed,and the oxygen content of the coating increased,indicating that the absorbent in the coating was corroded and oxidized by the corrosive medium infiltrated.By fitting the results of the AC impedance spectrum data with the equivalent circuit diagram,it was found that the corrosion failure of the samples went through three stages.The first was the stage of rapid decline in the corrosion protection performance of the coating from 0 to 48 h.The corrosion medium penetrated from the coating surface to the entire coating.The second was the fluctuation stage of the protective performance of the coating from 48 to 480 h.The oxidation product was a substance with high resistance and low capacitance,which restored the resistance value of the coating to a certain extent.The third was the stage of further rapid decline of the protective performance of the coating from 480 to 840 h.At this stage,the deeper layer of the absorbent was corroded and oxidized.The final test result indicated that the film value dropped by 69.72% compared with that before the test,indicating that the protective performance of the coating was significantly damaged.However,the average reflectivity of the radar wave of the 0 h sample was -4.27 and the 4 dB bandwidth was 70.07%,while the average reflectivity of the 840 h sample was -4.71,and the 4 d B bandwidth was 87.53%.The average difference of the reflectivity test results during the whole test process was less than 0.5 dB,indicating that the radar stealth performance did not decline.In the 0-840 h salt spray test,the absorbents were corroded and oxidized,but the stealth performance of radar absorbing coatings did not still decrease.In a certain period of time,the absorbents in radar absorbing coating are oxidized and corroded,which does not lead to the decline of radar stealth performance.The general understandings of scholars have been broken through by the test result.The effect law and the action mechanism of coating corrosion failure on the radar stealth performance have been intensively studied.