發(fā)布時間：2018-04-03 20:26

  本文選題：溶膠-凝膠法　切入點：氧化鋁陶瓷　出處：《華北理工大學》2017年碩士論文

【摘要】：隨著高功率微波技術的快速發(fā)展,研制適用于超高頻、高功率微波源的陶瓷輻射窗口成為眼下的當務之急。氧化鋁陶瓷(Al2O3)由于耐熱沖擊、介電損耗小、成本低廉等優(yōu)點成為迄今為止應用最廣泛的微波輻射窗口材料,所以對于氧化鋁基微波介質(zhì)陶瓷的研究具有十分重要的意義。采用溶膠-凝膠法制備Al2O3粉體,并研究以Ca O-Si O2-Ti O2、Mg O-Cu OTi O2、Mg O-Cu O-Ti O2-Eu2O3作為燒結助劑時,Al2O3陶瓷的燒結特性及介電性能。利用X射線衍射儀、掃描電子顯微鏡、透射電子顯微鏡以及能譜儀對Al2O3陶瓷的晶體結構、形貌及粒徑進行表征,通過網(wǎng)絡分析儀對Al2O3陶瓷的介電性能進行分析。結果表明:以分析純的硝酸鋁為原料,檸檬酸為絡合劑,初始溶液p H值為7時,采用溶膠-凝膠法成功制備了Al2O3干凝膠。干凝膠在1000℃下煅燒2 h后得到了Al2O3粉體,粒徑大約為50~80 nm,且其分散性良好。CaO的加入使Al2O3陶瓷的燒結溫度降至1450℃,但是在燒結過程中產(chǎn)生的第二相Ca Al12O19對Al2O3陶瓷的品質(zhì)因數(shù)Q·f值產(chǎn)生了一定的副作用。當燒結溫度為1450℃、Ca O添加量為0.4 wt.%時,Al2O3陶瓷的綜合性能較好:相對密度為98.61%,介電常數(shù)為9.88,Q·f值達到21957 GHz,諧振頻率溫度系數(shù)τf值為-21.353 ppm/℃。MgO的加入有效提高了Al2O3陶瓷的Q·f值,并且反應生成的Mg Al2O4相促進了Al2O3陶瓷的致密化。Ti O2的加入顯著改善了Al2O3陶瓷試樣的τf值,τf值最高為-15.635 ppm/℃。當燒結溫度為1500℃保溫4 h,Mg O含量為1.0 wt.%,Ti O2含量為0.8 wt.%時,Al2O3陶瓷的綜合性能良好:相對密度為98.83%,介電常數(shù)為9.89,Q·f值達到38028 GHz。Eu2O3的加入使Al2O3陶瓷的介電常數(shù)更加穩(wěn)定。隨著Eu2O3的變化,介電常數(shù)穩(wěn)定在9.90左右。當燒結溫度為1450℃,Eu2O3的添加量為0.25 wt.%時,燒結體的綜合性能較好:相對密度為98.21%,Q·f值為37984 GHz,τf值為-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，

本文編號：1706779