基于PSD的AlON透明陶瓷快速无压烧结及其机理研究

发布时间：2018-01-16 12:25

  本文关键词：基于PSD的AlON透明陶瓷快速无压烧结及其机理研究　出处：《大连海事大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： AlON透明陶瓷 无压烧结 粒度分布 双峰粉

【摘要】：AlON透明陶瓷是一种新型的功能陶瓷,它不仅具有良好的力学性能和化学稳定性,而且在红外到紫外波段均有良好的透光性,因此被广泛的应用于特种仪器制造、红外探测等领域,具有非常广阔的发展前景。目前世界各国多采用无压、热压的方式烧结AlON透明陶瓷,但无压烧结制备AlON透明陶瓷存在烧结温度高、保温时间长的问题,因此制备成本仍然较高。本文以碳热氮化还原法合成的AlON粉体为原料,添加0.5 wt%Y_2O_3为烧结助剂,以不同球磨工艺对AlON粉体进行球磨,获得两种具有不同粒度分布特征的AlON粉体:其一为单峰粉体,D50=1.1μm;其二为双峰粉体,特征峰位分别为1.1μm和2.2μm。无压烧结试验表明,双峰AlON粉体具有较好的烧结活性,其致密化温度较低,且致密化速率及相同温度下的致密化程度均高于单峰AlON粉体。双峰粉在无压烧结过程中的相转变研究表明:AlON粉体在升温至1400℃时转变为Al_2O_3和AlN,其中粗颗粒AlON转变为立方η-Al_2O_3和h-AlN,而细颗粒AlON转变为六方α-Al_2O_3和h-AlN,且随烧结温度继续升高,由于η-Al_2O_3和AlON的结构相似性,η-Al_2O_3和h-AlN在较低温度(1600～1700℃)重新转变为AlON,而 α-Al_2O_3 和 h-AlN 在 1700～1800 ℃转变为 AlON。进一步的微观结构演化研究表明:快速升温使样品中由AlON分解产生的Al_2O_3在重新转变成AlON相之前,颗粒保持近球形的、双峰分布的粒度分布特征。近球形的颗粒形貌有利于实现颗粒重排,双峰颗粒尺寸分布有利于晶粒生长,二者共同促进致密化进程。在Al_2O_3全部转变为AlON相之后,AlON大颗粒与大颗粒,大颗粒与小颗粒,小颗粒与小颗粒之间的传质过程同时快速进行,从而使得烧结后期试样中AlON晶粒快速长大,使气孔得到有效的排除从而获得高致密度样品。具有双峰粒度分布特征的AlON粉体,以40 ℃/min快速升温至1880℃保温150min,制备了高透过率的AlON透明陶瓷,3mm厚样品的红外透过率达81.8%,实现了 AlON透明陶瓷的快速低温烧结。
[Abstract]:AlON transparent ceramics is a new type of functional ceramics. It not only has good mechanical properties and chemical stability, but also has good transmittance in infrared and ultraviolet bands. Therefore, it is widely used in the manufacture of special instruments, infrared detection and other fields, and has a very broad development prospects. At present, AlON transparent ceramics are sintered by non-pressure and hot pressing in most countries in the world. However, AlON transparent ceramics prepared by pressureless sintering have the problems of high sintering temperature and long holding time, so the preparation cost is still high. In this paper, the AlON powder synthesized by carbothermal nitridation reduction method is used as raw material. Two kinds of AlON powders with different particle size distribution were obtained by adding 0. 5 wt%Y_2O_3 as sintering aids and different ball milling technology. One was single peak powder. D50C 1.1 渭 m; The second is bimodal powder, the characteristic peak is 1.1 渭 m and 2.2 渭 m respectively. The results of pressureless sintering show that bimodal AlON powder has good sintering activity and low densification temperature. The densification rate and densification degree at the same temperature were higher than that of single peak AlON powder. The phase transition of bimodal powder during pressureless sintering was studied. The AlON powder changed to Al_2O_3 and AlN when it was heated to 1400 鈩，

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