【正文】 od dispersion. The average grain size of AlON powder prepared with five different ratios mercial Al2O3 powder are all blow 5μm and with good dispersion. The powder with pure γAl2O3 as rawmaterial has best properties. The optimum technical of preparation of AlON powder in our work as follow: using Al ( wt%) and mercial γAl2O3 powder as starting material and calcined at 1700℃ for 3h.2. The preparation of transparent AlON ceramicThe biscuit with the diameter of 20mm was prepared with polyvinyl alcohol as adhesive and by dry pressed plus cold isostatic pressed method. It is necessary to eliminate adhesive from powder, discharge technology of green body through tests as follows: The temperature slowly increase to 120℃ for from room temperature and then increase to 500℃ for 2h in order to remove the anic matter.Transparent AlON ceramic can be reach with AlON powder prepared by homemade Al2O3 by sintering at 1880℃ for 10h. The sample is grey black and internal inhomogeneous, transmittance of sample is improved with prolonging of heat preservation time. And the densification was due to the mass transfer by diffusion.四川大學(xué)博士學(xué)位論文10Comparing with the AlON powder prepared by the homemade Al2O3 powder as rawmaterial, the AlON powder prepared by mercial Al2O3 powder has better sintering activity. Meanwhile, transparence of ceramic depend on sintering temperature, the transparence of ceramic at 1880℃ is higher than at 1860℃, more importantly, the transparence of ceramic is sensitive to the amount of sintering additives. An optimum additive of Y2O3 is %. The Mechanism of Y2O3 additive as follows: 1) the lattice distortion of main crystal phase is formed in order to promote sintering of ceramic. 2) The growth of grain is restrained by solute towed mechanism and it is benefit for sintering transparent ceramic. High transparent ceramic was obtained by twostep sintering method. The sintering mechanism is that the ceramic was reached to certain density at high temperature, and after holding the lower temperature in order to restrain the growth of grain size.3. Physical properties of transparent AlON ceramicThe transmittance of transparent AlON ceramics obtained at 1880℃ for 10h，20h and 40h were 10%, 40% and 60% and increased with increasing the wavelength. Compared with the homemade Al2O3 powder, the AlON powder prepared by mercial Al2O3 powder has better sintering activity and sintering sample has higher transmittance under the same condition. The 2mm sample with this powder and % Y2O3 sintered at 1880℃ for 10h has the max transmittance of 65%. Infrared transmittance of the sample via improved twostep sintering method reached a max transmittance about 72%. The cuton wavelength in UV band is 225nm, and the cutoff wavelength in the IR band is 7μm. The results of transmission spectra of the sample showed that with the increase of wavelength the infrared transmittance of transparent AlON ceramic increased. The result of light scattering theory showed that the transmittance of sample increased with increasing wavelength because of large pores or not enough sintering additive. Phase position of transparent AlON ceramic showed that there was no phasetransformation with holding time of temperature. The density analysis showed that transparence of sample depend on the density of sample based on our 四川大學(xué)博士學(xué)位論文11experimental results and analysis. As a result, the density of transparent AlON ceramic by twostep sintering method is consistent with theoretical density. Fresh section of transparent AlON ceramic with % Y2O3 sintered at 1880℃ for different holding time observed by SEM showed that the grain growth and the removal of pores occurred with increasing holding time. However, there is certain pore in the sample for 40h because of the lack of sintering additive and the low sintering activity of AlON powder produced by homemade AlON powder. The bending strength of sample at 1880℃ for 10h with % Y2O3 additive can reach to 283MPa, moreover, the hardness of sample increased with increasing the density of sample. The Vickers hardness of high transparent AlON ceramic is about 177。 ALON 透明陶瓷材料 ............................................................................................................. 1 167。 本論文研究工作 .................................................................................................................... 1 第二章 ΓALON 粉體的制備研究 ....................................................................... 1 167。 鋁熱還原氮化過程研究 ................................................................................................. 1 167。 AlON 透明陶瓷氣氛燒結(jié) .............................................................................................. 1 167。 高透明 AlON 陶瓷的兩步燒結(jié)法制備 ........................................................................ 1 167。 ALON 陶瓷樣片的密度 ......................................................................................................... 1 167。 AlON 陶瓷在氧氣中的非等溫穩(wěn)定性研究 .................................................................. 1 167。 陶瓷的概念及其發(fā)展 [1~9]材料是人類社會(huì)進(jìn)步的標(biāo)志，人類文明、社會(huì)進(jìn)步的整個(gè)歷史與材料的發(fā)展史休戚相關(guān)。四川大學(xué)博士學(xué)位論文 2 先進(jìn)陶瓷的產(chǎn)生，大大擴(kuò)展了陶瓷的概念，現(xiàn)在陶瓷已經(jīng)是所有無機(jī)材料的總稱，它和金屬和有機(jī)高聚物一起，成為現(xiàn)代工程材料的重要組成部分。透明陶瓷不僅具有良好的透明性，而且具有陶瓷材料的強(qiáng)度高、介電性能優(yōu)良、低電導(dǎo)率、高熱導(dǎo)性、耐腐蝕和能在高溫高壓下工作等特性，逐漸在照明技術(shù)、光學(xué)、特種儀器制造、無線電子技術(shù)和高溫技術(shù)等領(lǐng)域獲得日益廣泛的應(yīng)用。1. 陶瓷粉體的制備粉體是大量固體粒子的集合系，其由一個(gè)個(gè)固體顆粒組成，有很多固體的屬性。a. 固相熱分解法固相熱分解法的反應(yīng)形式通常如下（S 代表固相，G 代表氣相）： 11121S?? 122 131式 11 和式 12 是最常見的反應(yīng)方式，一般用于單一金屬氧化物粉體的制備。d. 溶出法所謂溶出法，即對有兩種或兩種以上物質(zhì)組成的混合物中，通過加入酸或堿溶出不需要的物相而獲得微粉的方法。噴霧法根據(jù)霧化和凝聚過程可分為三種方法：將液滴進(jìn)行干燥并隨即捕集，捕集后直接或者經(jīng)過熱處理后作為產(chǎn)物顆粒，是噴霧干燥法；將液滴在氣相中進(jìn)行水解是噴霧水解法；使液滴在游離于氣相中的狀態(tài)下進(jìn)行熱處理的方法是噴霧焙燒法。3) 氣相法氣相法是直接利用氣體或者通過各種手段將物質(zhì)變成氣體，使之在氣體狀態(tài)下發(fā)生物理變化或化學(xué)反應(yīng)，最后在冷卻過程中凝聚長大形成納米微粒的方法。3） 塑化塑化是在物料中加入塑化劑使其具有可塑性的過程。對透明陶瓷來說，成型工藝對陶瓷成品的燒結(jié)和最終性能，尤其是透光性具有重要的影