本文關鍵詞：基于PSD的AlON透明陶瓷快速無壓燒結及其機理研究　出處：《大連海事大學》2017年碩士論文　論文類型：學位論文

  更多相關文章： AlON透明陶瓷 無壓燒結 粒度分布 雙峰粉

【摘要】：AlON透明陶瓷是一種新型的功能陶瓷,它不僅具有良好的力學性能和化學穩(wěn)定性,而且在紅外到紫外波段均有良好的透光性,因此被廣泛的應用于特種儀器制造、紅外探測等領域,具有非常廣闊的發(fā)展前景。目前世界各國多采用無壓、熱壓的方式燒結AlON透明陶瓷,但無壓燒結制備AlON透明陶瓷存在燒結溫度高、保溫時間長的問題,因此制備成本仍然較高。本文以碳熱氮化還原法合成的AlON粉體為原料,添加0.5 wt%Y_2O_3為燒結助劑,以不同球磨工藝對AlON粉體進行球磨,獲得兩種具有不同粒度分布特征的AlON粉體:其一為單峰粉體,D50=1.1μm;其二為雙峰粉體,特征峰位分別為1.1μm和2.2μm。無壓燒結試驗表明,雙峰AlON粉體具有較好的燒結活性,其致密化溫度較低,且致密化速率及相同溫度下的致密化程度均高于單峰AlON粉體。雙峰粉在無壓燒結過程中的相轉變研究表明:AlON粉體在升溫至1400℃時轉變?yōu)锳l_2O_3和AlN,其中粗顆粒AlON轉變?yōu)榱⒎溅?Al_2O_3和h-AlN,而細顆粒AlON轉變?yōu)榱溅?Al_2O_3和h-AlN,且隨燒結溫度繼續(xù)升高,由于η-Al_2O_3和AlON的結構相似性,η-Al_2O_3和h-AlN在較低溫度(1600～1700℃)重新轉變?yōu)锳lON,而 α-Al_2O_3 和 h-AlN 在 1700～1800 ℃轉變?yōu)?AlON。進一步的微觀結構演化研究表明:快速升溫使樣品中由AlON分解產(chǎn)生的Al_2O_3在重新轉變成AlON相之前,顆粒保持近球形的、雙峰分布的粒度分布特征。近球形的顆粒形貌有利于實現(xiàn)顆粒重排,雙峰顆粒尺寸分布有利于晶粒生長,二者共同促進致密化進程。在Al_2O_3全部轉變?yōu)锳lON相之后,AlON大顆粒與大顆粒,大顆粒與小顆粒,小顆粒與小顆粒之間的傳質過程同時快速進行,從而使得燒結后期試樣中AlON晶粒快速長大,使氣孔得到有效的排除從而獲得高致密度樣品。具有雙峰粒度分布特征的AlON粉體,以40 ℃/min快速升溫至1880℃保溫150min,制備了高透過率的AlON透明陶瓷,3mm厚樣品的紅外透過率達81.8%,實現(xiàn)了 AlON透明陶瓷的快速低溫燒結。
[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，

本文編號：1433135