低温放电等离子烧结法制备氮化硅陶瓷

Low Temperature Sintering of Silicon Nitride Ceramics by Spark Plasma Sintering Technique

分别以MgO–Al2O3或MgO–AlPO4作为烧结助剂,采用放电等离子体低温快速烧结方法制备了主相为α相的Si3N4陶瓷材料。采用X射线衍射和扫描电子显微镜分析了样品的物相组成和显微结构;研究了烧结助剂及其含量、烧结温度对陶瓷样品的相对密度与力学性能的影响。结果表明:当采用4%(质量分数,下同)MgO–4%Al2O3烧结助剂时,1 400℃烧结的陶瓷样品的相对密度和弯曲强度达到最高,分别为81%和182 MPa,且随烧结助剂中Al2O3含量的增加,样品的相对密度和弯曲强度降低。而当采用4%MgO–16%AlPO4烧结助剂时,1 300℃烧结的陶瓷样品的相对密度和弯曲强度分别达到96%和366.5 MPa,且样品的相对密度和弯曲强度随烧结温度的升高而增大。表明MgO–AlPO4可以用作Si3N4低温烧结的一种有效烧结助剂,可降低陶瓷的烧结温度和提高其力学强度。

The α-Si3N4 matrix ceramics were prepared by spark plasma sintering using MgO–Al2O3 and MgO–AlPO4 as the sintering additives,respectively.The phase composition and microstructure of the samples were analyzed by X-ray diffraction and scanning electron microscope.The effects of sintering additives and sintering temperature on the relative density and mechanical properties of the samples were investigated.The results show that when 4%（in mass,the same below） MgO–4%Al2O3 were used as the sintering additives,the relative density and bending strength of the sample sintered at 1 400 ℃ reach 81% and 182 MPa,respectively,and the relative density and bending strength of the samples reduce with the increase of Al2O3 content in the sintering additive.When 4%MgO–16%AlPO4 were used as the sintering additives,the relative density and bending strength of the sample sintered at 1 300 ℃ reach 96% and 366.5 MPa,respectively,and the relative density and bending strength of the samples increase with the rise of sintering temperature.It indicates that the MgO–AlPO4 as sintering additives play a significant role in the low temperature sintering of Si3N4 ceramics,and not only reduce the sintering temperature but also improve the mechanical property of the sintered Si3N4 ceramics.