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线圈骨架注射模设计
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The nanocomposite multilayer film was prepared using sol–gel method. The TiO2and ferrite sols were synthe- sized respectively first. The TiO2sol was obtained after adding tetrabutyl titanate, diethanolanine and a little of watertotheabsolutealcohol,withstirringfortwohours. According to the composition of BaFe10.5Al1.5O19, BaFe10.1Al1.9O19 and BaFe11.4Cr0.6O19 respectively, stoichiometric amount of barium nitrate, ferric nitrate, aluminum nitrate or chromium nitrate were dissolved in 60?C ethylene glycol with the addition of citric acid. After the ethylene diamine was added to adjust the pH value to 7.0, the ferrites precursor sols were formed. Depending on the weight ratio of ferrite to titanium dioxide for 3:5, three mixed sols were prepared. The mixed sol of BaFe10.1Al1.9O19and TiO2 was first spin coated onto a quartz glass plate, which had beenpreviouslycleanedbydeionizedwaterandalcohol. The spin speed was 3,000 rpm and the spin time was 15 s. The composite film was dried at 60 ?C for 30 min. Then the above spin process was repeated successively with the other two mixed sols containing BaFe10.5Al1.5O19and BaFe11.4Cr0.6O19. Finally, three layer composite films were calcined at 850 ?C for one hour. Surface morphology of the multilayer film was analyzed with atomic force microscopy (AFM), which was performed on the UHV-SPM. The scanning area was 2 ·2 lm. The crystalline structures of multilayer film were determined with X-ray diffraction (XRD) carried out on a Bruker-AXS D8 Advanced diffrac- tometer with Cu Karadiation in the 2h range from 10? to 90?, by steps of 0.02?. The microwave absorption property was expressed in microwave loss efficiency. The composite film was scraped off the quartz glass and collected together. The powders were filled into a 30 · 30 · 3 mm polytetrafluoroethylene box and pressed tightly. The transmission and reflection coef- ficients were measured with microstrip transmission line in 8722ES vector network analyzer in the fre- quency range from 5 GHz to 15 GHz. The microwave loss AdBwas calculated according to Eq. 1. where PTis the transmission wave power; PIis the incident wave power and PR is the reflection wave power. The microwave loss of the polytetrafluoroeth- ylene box was subtracted. |
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