高导热氮化硅陶瓷的快速制备和性能控制

Rapid Preparation and Performance Control of Silicon Nitride Ceramics with High Thermal Conductivity

氮化硅陶瓷力学性能优异,理论热导率高,是大功率电力电子器件的关键热管理材料。但是,高导热氮化硅陶瓷烧结温度高、保温时间长,因此制备成本居高不下,对于产业化应用不利。本研究提出了一种快速制备高导热氮化硅陶瓷的方案。以Y2O3-MgO-C作为烧结助剂,以高纯硅粉作为起始原料,通过流延成型和硅粉氮化制备素坯,在1900℃、0.6MPa保温2h制备出高导热氮化硅陶瓷。研究了C的添加量对于氮化硅陶瓷的致密化、晶相、微结构、力学性能以及热导率的影响规律。最终制备的氮化硅陶瓷密度可以达到99%以上,热导率达到98W/m·K。

Si3N4 ceramics are prospective substrate candidates for power electron devices because of the excellent mechanical properties and high theoretical thermal conductivity.However,the development of high thermal conductivity Si3N4 is quite difficult,because the high sintering temperature and long holding time under N2 pressure lead to high production cost,which is not conductive to industrial applications.In this paper,a relative fast preparation process was proposed using Y2O3-MgO-C as the sintering additive and silicon powder as the starting material.High thermal conductivity Si3N4 ceramic was prepared through tape casting,nitridation and gas pressure sintering at 1900℃,0.6 MPa with 2 hholding.The influences of carbon addition on the sintering behavior,phase,microstructure,mechanical properties and thermal conductivity of Si3N4 were studied.Finally Si3N4 ceramics with the relative density of 99% and the thermal conductivity of 98 W/m K were obtained.