含有定向排列颗粒的氮化硅陶瓷各向异性研究

通过添加α-Si3N4晶须,利用流延成型和热压烧结技术制备含有定向排列颗粒、各向异性的Si3N4陶瓷。研究α-Si3N4相在流延膜及烧结块体中的分布状态,并通过XRD、SEM和力学性能对流延膜和烧结块体的各向异性进行表征。结果表明,1 550℃下烧结制备的块体T(与流延方向平行的平面)、N(与流延方向垂直的平面)、P(侧面)三个面的I(210)/I(102)值与等轴状α-Si3N4粉体的相应值比较,其中T面的值较大,N面和P面的值较小;在T面的显微结构中存在平行于流延方向排列的大颗粒;试样不同面的力学性能(断裂韧性和抗弯强度)中,T面最好,P面次之,N面最差;I(210)/I(102)值、显微结构、力学性能测试结果表明所制备的氮化硅陶瓷存在各向异性。

Anisotropy study of Si3N4ceramic with aligned and elongated grains

Silicon nitride(Si3N4) ceramics with aligned and elongated grains were prepared by adding α-Si3N4 whiskers and using tape casting and hot-press sintering.The distribution of α-Si3N4 phase in the green tapes and sintering samples was studied,and the green tapes and sintering samples were characterized by XRD,SEM and mechanical properties.The results show that α-Si3N4 whiskers are aligned along the direction of tape casting in the green tapes.The I(210)/I(102) value of T plane(parallel to the tape casting direction) in the sample sintered at 1 550 ℃ is higher than that of α-Si3N4 powders,while that of N plane(normal to the tape casting direction) and P plane(the side plane) is less.There exist large grains aligning along the direction parallel to that of tape casting.The mechanical properties in T plane are best,followed by P plane and N plane.The I(210)/I(102) value,microstructure and mechanical properties suggest that α-Si3N4 phase is aligned better in the substrate and silicon nitride ceramics is anisotropic.