Effect of SmFeN content on the coating organization and electromagnetic loss of plasma sprayed SmFeN/LaMAcomposites
The phase structure of Sm2Fe17Nx(SmFeN)/LaMA(LaMgAlO)composite wave-absorbing coating samples with different mass ratios(2∶1,1∶1,1∶2)plasma sprayed at 35 kW as well as the values of electro-magnetic parameters(ε',ε",μ',μ")and electromagnetic reflectance RL of the samples within the electromag-netic wave frequency band of 0-18 GHz were observed and analyzed,and the its electromagnetic loss mechanism was investigated.The results show that the SmFeN content has a large influence on the phase composition and wave-absorbing properties of the sprayed samples.The sprayed samples include Fe,Fe8N,Fe16N2,Al2O3,AlN,Fe12Sm,La3MgA1O7 and LaMgAl11O19 phases.The SmFeN increases the relative content of the Fe,Fe8N and Fe16N2 phases,decreases the relative content of the Fe12Sm,La3MgAlO7 and LaMgAl11O19 phases,and has no effect on the AlN phase.The amorphous phase appears at high temperatures,and the relative intensity of the amorphous phase increases as the temperature rises,resulting in poor wave-absorbing properties of the samples at high temperatures.The relative content of LaMgAl11O19 decreases the ε',ε"of the samples,optimizing the impedance matching of the sprayed samples.The relative content of AlN increases the valley of ε'and the peak of ε"to the high frequency.The mass ratio of the sprayed sample with the best performance is SmFeN∶LaMA=1∶2,the reflectivity reaches-40.31 dB at 4.24 GHz,4.83 mm,and the bandwidth and thickness range of the effective absorption(RL＜-10 dB)are 3.61-6.94 GHz,2.93-5 mm and 8.4-12.2 GHz,1.98-3.45 mm,re-spectively.The lowest reflectance of the 1∶1 ratio sprayed samples at 40 ℃,400 ℃,and 700 ℃ are-5.46 dB,-3.62 dB,and-0.37 dB in the 8～18 GHz bands respectively.The room temperature test values of the bowtie beams show that the RL values resulted from electromagnetic parameters are agreeable with the test values.
万方数据
维普
