氧化铝基微波窗口材料的制备及性能研究

发布时间：2018-04-03 20:26

  本文选题：溶胶-凝胶法　切入点：氧化铝陶瓷　出处：《华北理工大学》2017年硕士论文

【摘要】：随着高功率微波技术的快速发展,研制适用于超高频、高功率微波源的陶瓷辐射窗口成为眼下的当务之急。氧化铝陶瓷(Al2O3)由于耐热冲击、介电损耗小、成本低廉等优点成为迄今为止应用最广泛的微波辐射窗口材料,所以对于氧化铝基微波介质陶瓷的研究具有十分重要的意义。采用溶胶-凝胶法制备Al2O3粉体,并研究以Ca O-Si O2-Ti O2、Mg O-Cu OTi O2、Mg O-Cu O-Ti O2-Eu2O3作为烧结助剂时,Al2O3陶瓷的烧结特性及介电性能。利用X射线衍射仪、扫描电子显微镜、透射电子显微镜以及能谱仪对Al2O3陶瓷的晶体结构、形貌及粒径进行表征,通过网络分析仪对Al2O3陶瓷的介电性能进行分析。结果表明:以分析纯的硝酸铝为原料,柠檬酸为络合剂,初始溶液p H值为7时,采用溶胶-凝胶法成功制备了Al2O3干凝胶。干凝胶在1000℃下煅烧2 h后得到了Al2O3粉体,粒径大约为50~80 nm,且其分散性良好。CaO的加入使Al2O3陶瓷的烧结温度降至1450℃,但是在烧结过程中产生的第二相Ca Al12O19对Al2O3陶瓷的品质因数Q·f值产生了一定的副作用。当烧结温度为1450℃、Ca O添加量为0.4 wt.%时,Al2O3陶瓷的综合性能较好:相对密度为98.61%,介电常数为9.88,Q·f值达到21957 GHz,谐振频率温度系数τf值为-21.353 ppm/℃。MgO的加入有效提高了Al2O3陶瓷的Q·f值,并且反应生成的Mg Al2O4相促进了Al2O3陶瓷的致密化。Ti O2的加入显著改善了Al2O3陶瓷试样的τf值,τf值最高为-15.635 ppm/℃。当烧结温度为1500℃保温4 h,Mg O含量为1.0 wt.%,Ti O2含量为0.8 wt.%时,Al2O3陶瓷的综合性能良好:相对密度为98.83%,介电常数为9.89,Q·f值达到38028 GHz。Eu2O3的加入使Al2O3陶瓷的介电常数更加稳定。随着Eu2O3的变化,介电常数稳定在9.90左右。当烧结温度为1450℃,Eu2O3的添加量为0.25 wt.%时,烧结体的综合性能较好:相对密度为98.21%,Q·f值为37984 GHz,τf值为-29.548ppm/℃。
[Abstract]:With the rapid development of high power microwave technology, it is urgent to develop ceramic radiation window suitable for UHF and high power microwave sources.Alumina ceramic Al _ 2O _ 3) has become the most widely used microwave radiation window material due to its heat shock, low dielectric loss and low cost, so it is of great significance to study the alumina based microwave dielectric ceramics.Al2O3 powders were prepared by sol-gel method. The sintering properties and dielectric properties of Al _ 2O _ 3 ceramics with Ca O-Si O2-Ti O _ 2mg O-Cu OTi O _ 2O _ 2mg O-Cu O-Ti O2-Eu2O3 as sintering aids were studied.The crystal structure, morphology and particle size of Al2O3 ceramics were characterized by X-ray diffractometer, scanning electron microscope, transmission electron microscope and energy spectrometer. The dielectric properties of Al2O3 ceramics were analyzed by network analyzer.The results showed that Al2O3 xerogel was successfully prepared by sol-gel method using pure aluminum nitrate as raw material, citric acid as complexing agent and initial solution pH being 7.After calcined at 1000 鈩，

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