微观结构和光学性能
(武汉理工大学 材料复合新技术国家重点实验室， 武汉 430070)
摘 要: 采用放电等离子烧结技术， 添加质量分数为3 ％的CaF2作为烧结助剂， 制备了透明氮化铝 (AlN) 陶瓷。 样品在烧结温度1 800 ℃， 30 MPa压力下保温15 min， 达到了99.5％的相对密度和52.7％的最大透过率。 SEM、 XRD、 TEM和EDX结果表明， 烧结体具有很高的致密度、 纯度， 良好的晶粒形貌和微观晶体结构， 晶界和三角晶界处观察不到第二相的存在。 CaF2的添加引入液相烧结， 促进AlN晶粒的生长和烧结体的致密化， 并且与AlN颗粒反应生成的氟化物和Ca-Al-O化合物能够从烧结体中逸出， 进一步净化烧结体， 是制备透明AlN陶瓷的有效助剂。 放电等离子烧结技术具有烧结快速、 烧结体致密度高的特点， 是制备透明AlN陶瓷的有效方法。
关键字: 放电等离子烧结； 透明AlN陶瓷； 透过率； 微观结构
（ State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China）
Abstract: Transparent AlN ceramics were prepared by spark plasma sintering (SPS) technique with 3% (mass fractin) CaF2 as sintering additive. Samples achieved 99.5% relative density and 52.4% maximum transmittance after 15 min holding time by spark plasma sintering at 1 800 ℃ and 30 MPa. The results from XRD, SEM, TEM and EDX show that the sintered bodies are densely compacted and highly pure with fine grain size and uniform microstructures, and no secondary phases are observed at the grain boundaries or triple grain junctions. The presence of CaF2 induces liquid phase sintering, which promotes the growth of AlN grains and the densification of the sintered bodies. The resultants of fluorides and Ca-Al-O compounds from reaction between CaF2 and AlN can evaporate from sintered bodies and further purify the sintered bodies, which indicates that CaF2 is an effective sintering additive. SPS is an effective method for the fabrication of transparent AlN ceramics.
Key words: spark plasma sintering (SPS); transparent AlN ceramics; transmittance; microstructures
