五氧化二铌与二氧化硅作用下氧化铝晶粒的各向异性生长(英文)

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1 500℃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%.

ANISOTROPIC GRAIN GROWTH OF ALUMINA BY SYNERGISTIC EFFECTS OF NIOBIUM PENTOXIDE AND SILICON DIOXIDE

Grain growth caused by doping alpha-alumina with small amounts of silicon dioxide and niobium penroxide added singly or together was investigated in contrast to undoped alumina. When they were sintered at 1500 ℃ for 2 h, the alumina grain for singly doped specimen is equiaxed, and the niobium promotes excessive the grain growth of alumina. But the codoped specimen exhibited anisotropic grain growth and the volume is very large. High resolution transmission electron microscope photograph reveals that a thin amorphous layer (0.8-4 nm) is presented at some grain boundaries. Liquid phase may affect the energy of the grain boundary and induces anisotropic grain growth. The research results also show that when the niobium content is constant, the fracture toughness is enhanced by 42% and the bending strength is increased by 80% via adjusting the silicon contents.