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研究了少量SiO2和Nb2O5掺杂对α-氧化铝晶粒生长的影响。单一掺杂1500℃煅烧2h的样品均表现为晶粒的等轴状,且铌掺杂明显促进了氧化铝晶粒的生长。SiO2与Nb2O5的共掺杂则导致晶粒各向异性优势生长。高分辨透射电镜照片表明:在一些晶粒晶界出现0.8～4nm的无定形层,晶界处的液相同样影响晶界能,从而诱导各向异性生长。结果表明:在固定铌含量的基础上,少量二氧化硅使材料的断裂韧度提高42%,抗弯强度提高约80%。
The effects of a small amount of SiO2 and Nb2O5 doping on the α-alumina grain growth were studied. The samples doped with single doping at 1500 ℃ for 2h showed the equiaxed grains, and the doping of niobium significantly promoted the growth of the alumina grains. Co-doping with SiO2 and Nb2O5 leads to the dominant growth of grain anisotropy. High-resolution transmission electron micrographs show that an amorphous layer of 0.8-4 nm occurs at some grain boundaries, and the liquid phase at the grain boundaries also affects the grain boundary energy, thereby inducing the anisotropic growth. The results show that the addition of a small amount of silica increases the fracture toughness of the material by 42% and the flexural strength by about 80% on the basis of the fixed niobium content.