Preparation Of AlN Ceramics With High Thermal Conductivity By Doping Rare Earth Oxides

AlN ceramics have high thermal conductivity and excellent comprehensive performance,and have great application prospects in semiconductor substrate materials,electronic packaging materials,etc.but AlN is difficult to sinter and compact,and high density is the prerequisite for excellent performance.In order to obtain high thermal conductivity AlN ceramics,on the basis of previous studies,this article selects rare earth element oxides as sintering aids for hot-press sintering research,in order to obtain AlN ceramics with high thermal conductivity.This article first studied the effect of hot pressing sintering process on the properties of AlN ceramics doped with 5wt%Y₂O₃.The results show that the setting of related process parameters of hot pressing sintering has an important influence on the performance of AlN ceramics.Compared with vacuum sintering,the performance of samples sintered in a nitrogen atmosphere is higher,and pre-pressing the AlN powder before sintering can effectively improve the performance.The density of AlN ceramics,too high sintering temperature will also cause the density of AlN ceramics to decrease.In this experiment,the density of AlN ceramics obtained at a sintering temperature of1800°C is the highest.Density is not the only factor that affects thermal conductivity,but is also affected by phase composition,microstructure and other factors.In this experiment,the relative density of AlN increased from 96.97%to 98.67%,and the thermal conductivity increased from 153.0W·m^-1·K^-1 to 166.0W·m^-1·K^-1 by pre-pressing.On the basis of the above research,in order to further improve the thermal conductivity of AlN ceramics,Ce O₂ and Y₂O₃ were added to form a binary sintering aid system for hot-press sintering research.The results show that the addition of Ce O₂ can improve the thermal conductivity of AlN ceramics.At the same time,adding 5wt%Y₂O₃and 1wt%Ce O₂ AlN powder under the conditions of pre-pressing 30min,sintering temperature 1900℃,sintering pressure 40MPa,nitrogen atmosphere,and holding pressure for 2h,The AlN ceramic with the best thermal conductivity is obtained,with a relative density of 96.15%and a thermal conductivity of 207.8W·m^-1·K^-1.