热压烧结制备AlN/BN复相陶瓷及其性能研究

Fabrication and Properties of AlN / BN Composite Ceramics by Hot-Pressing Sintering

以氮化铝（AlN）粉和高活性六方氮化硼（h-BN）粉为原料,不添加烧结助剂,采用热压烧结法制备了Al N/BN（20vol%）复相陶瓷。研究了烧结温度（1750~1900℃）对复相陶瓷相对密度、物相组成、显微结构、力学性能、热导率及介电性能的影响。结果表明,在1850℃以上可以制备出相对密度大于98.6%的致密AlN/BN复相陶瓷。试样显微结构均匀,晶粒细小,晶界干净,无明显杂质相,h-BN未形成明显的卡片房式结构。随着烧结温度的提高,试样的相对密度、力学性能、热导率及介电性能（1 MHz）均显著提高。1900℃烧结的试样性能最优,相对密度99.3%,抗弯强度482±42 MPa、断裂韧性4.4±0.4 MPa·m1/2、维氏硬度8.56±0.33GPa、热导率47.2 W·m-1·K-1、介电常数7.64,介电损耗4.62×10^-4。

AlN / BN composite ceramics were prepared by hot-pressing sintering,using AlN powder and hBN powder as raw material,without adding sintering aids. The effects of sintering temperature（ 1750-1900 ℃） on the relative density,phase composition,microstructure,mechanical properties,thermal conductivity and dielectric properties of the composite ceramics were investigated. The results show that the dense AlN / BN composite ceramics,a relative density more than 98. 6%,can be prepared when the sintering temperature reaching 1850 ℃. The as-prepared samples have homogeneous microstructure,fine grain size and clean grain boundary. The accumulation resulting from h-BN plate-like grains and significant impurity phase were not observed. As the sintering temperature increasing,the relative density,mechanical properties,thermal conductivity and dielectric properties（ 1 MHz） of the as-prepared samples were significantly improved. When the sintering temperature is 1900 ℃,the as-prepared samples have a relative density 99. 3%,bending strength 482 ± 42 MPa,fracture toughness 4. 4 ± 0. 4 MPa ·m1 /2,Vickers hardness 8. 56 ± 0. 33 GPa,thermal conductivity 47. 2 W·m-1·K-1,dielectric constant7. 64,and dielectric loss 4. 62 × 10-4.