【摘要】：α-Al_2O_3陶瓷作為一種重要的陶瓷材料,具有獨(dú)特的化學(xué)、電學(xué)及力學(xué)性能,它屬于剛玉結(jié)構(gòu),具有高硬度、高強(qiáng)度、耐磨損、耐高溫、耐腐蝕、絕緣性好等特性。片狀α-Al_2O_3粉體材料除了具備普通氧化鋁材料的優(yōu)良性能,還具有特殊的片狀二維結(jié)構(gòu),并且表面活性適中,附著力比較好,對光線的反射能力和屏蔽效應(yīng)高等。片狀α-Al_2O_3在化妝品、珠光顏料、耐火材料以及增韌陶瓷等領(lǐng)域都有著廣泛的應(yīng)用前景。本研究結(jié)合溶膠凝膠法與熔鹽法,將硫酸鋁作為原料,硫酸鉀、硫酸鈉為熔鹽,通過一系列液相和固相反應(yīng)制備了粒徑大、厚度薄的片狀氧化鋁材料。本文通過光學(xué)顯微鏡、掃描電子顯微鏡、X射線衍射儀、綜合熱分析儀及紅外光譜儀等檢測表征手段,考察了不同鋁鹽原料對合成的片狀氧化鋁形貌的影響,探索了溶膠凝膠和熔鹽過程中的工藝參數(shù)包括反應(yīng)終點(diǎn)pH、反應(yīng)溫度、陳化時間及燒結(jié)溫度對終產(chǎn)物的影響,同時詳細(xì)研究了二氧化鈦、硫酸鋅、硫酸亞錫或其混合物等添加劑對片狀氧化鋁的形貌與徑厚比的影響,最后對氧化鋁的生長機(jī)理進(jìn)行了研究,探索片狀氧化鋁的形成的機(jī)理。研究結(jié)果表明:在鋁源的選擇上,選用硫酸鋁可制備出尺寸大且分布均勻的片狀α-Al_2O_3晶粒。在熔鹽的選擇上,鋁源與熔鹽摩爾比為1:4時,制備的片狀α-Al_2O_3表面平整而有光澤。在溶膠凝膠過程中,隨著陳化時間增長,形成的片狀氧化鋁的晶粒尺寸越大,粒徑分布越窄。煅燒溫度在1000~1200oC,終產(chǎn)物都能得到片狀α-Al_2O_3晶體,但是1100oC下徑厚比最大,隨著燒結(jié)溫度的升高,片狀氧化鋁的晶體粒徑增大較緩,但厚度增加較明顯,導(dǎo)致徑厚比減小。另外選擇合適的添加劑能顯著促進(jìn)α-Al_2O_3晶體的各向異性生長,并且可以減少細(xì)碎晶體的比例,使粒徑分布更均勻。研究發(fā)現(xiàn)添加2 wt%硫酸鋅和0.4 wt%硫酸亞錫,可以得到粒徑為25~40μm、厚度為200~300 nm、徑厚比大于100、表面光滑的片狀氧化鋁粉體。結(jié)合晶體生長的不連續(xù)性現(xiàn)象,氧化鋁的生長過程可能是相變誘導(dǎo)取向聚結(jié)的過程。
[Abstract]:As an important ceramic material, 偽 -Al2O3 ceramic has unique chemical, electrical and mechanical properties. It belongs to corundum structure and has the characteristics of high hardness, high strength, wear resistance, high temperature resistance, corrosion resistance and good insulation. In addition to the excellent properties of ordinary alumina, the lamellar 偽 -Al _ 2O _ 3 powder also has a special two-dimensional flake structure with moderate surface activity, good adhesion, and high light reflection and shielding effect. Lamellar 偽 -Al2O3 is widely used in cosmetics, pearlescent pigments, refractories and toughened ceramics. In this study, aluminum sulfate was used as raw material, potassium sulfate and sodium sulfate as molten salt, and a series of liquid-phase and solid-state reactions were used to prepare flake alumina material with large particle size and thin thickness, combined with sol-gel method and molten salt method. By means of optical microscope, scanning electron microscope, X-ray diffractometer, comprehensive thermal analyzer and infrared spectrometer, the influence of different aluminum salt materials on the morphology of flake alumina was investigated. The effects of reaction terminal pH, reaction temperature, aging time and sintering temperature on the final product of sol-gel and molten salt were investigated. At the same time, titanium dioxide and zinc sulfate were studied in detail. The effect of additives such as tin sulfate or its mixture on the morphology and diameter to thickness ratio of flake alumina was studied. Finally, the growth mechanism of aluminum oxide was studied, and the formation mechanism of flake alumina was explored. The results show that the large size and uniform distribution of 偽 -Al _ 2O _ 3 grains can be prepared by using aluminum sulfate in the selection of aluminum source. When the molar ratio of aluminum source to molten salt is 1:4, the surface of 偽 -Al _ 2O _ 3 prepared is smooth and glossy. In the sol-gel process, the larger the grain size and the narrower the particle size distribution are, the longer the aging time is. When the calcination temperature is 1000 ~ 1200oC, the final products can obtain 偽 -Al _ 2O _ 3 crystal, but the diameter to thickness ratio at 1100oC is the largest. With the increase of sintering temperature, the particle size of flake alumina increases slowly, but the thickness increases obviously, which results in the decrease of diameter to thickness ratio. In addition, the selection of appropriate additives can significantly promote the anisotropic growth of 偽 -Al2O3 crystals, reduce the proportion of fine crystals, and make the particle size distribution more uniform. It is found that the flake alumina powder with a diameter of 25 渭 m, a thickness of 200 ~ 300 nm, a diameter ratio of more than 100 and a smooth surface can be obtained by adding 2 wt% zinc sulfate and 0.4 wt% stannous sulfate. In combination with the discontinuity of crystal growth, the growth process of alumina may be a phase transition induced orientation coalescence process.
【學(xué)位授予單位】：湖北工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ133.1

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