对铌合金C103基体上真空蒸镀的Al膜进行阳极氧化处理获得阳极氧化铝(AAO)膜, 利用电镀技术在AAO膜上制备Ni表层, 通过高温处理研究元素通过AAO膜的扩散行为. 结果表明: 没有中间层的Ni/C103及以纯Al膜作为中间层的Ni/Al/C103样品, 涂层和基体间的元素扩散严重; 而以AAO膜为中间层的Ni/AAO/C103样品, 涂层和基体间的元素扩散受到明显抑制. 经900 ℃热处理后, Ni/C103, Ni/Al/C103及Ni/AAO/C103样品其外层中Nb含量分别为7.05%, 5.08%和3.55%; 基体中的Ni含量分别为6.84%, 3.62%和2.85%; AAO膜作为中间层有较强的元素扩散阻挡能力. 在900 ℃退火后, Ni/C103和Ni/Al/C103样品表面均生成了NbNi₃相, 而Ni/AAO/C103样品并未出现Nb和Ni的反应生成物. 通过Fick定律计算得知, 900 ℃时Ni在AAO膜的扩散系数为3.28×10^-14 m²/s, Nb为2.16×10^-14 m²/s; 1000 ℃时Ni的扩散系数上升至1.03×10^-13 m²/s, Nb为3.58×10^-14 m²/s.

Element interdiffusion will accelerate failure of surface coating systems after a long time service at high temperature. To extend service life of the coatings, developing a diffusion barrier between the coating and the substrate is considered as an efficient way. Many research results showed that a diffusion barrier with single function such as metallic or ceramic one can not meet requirements for strong barrier ability and strong interfacial strength of the coatings onto the substrate at the same time. Anodic aluminum oxide (AAO) film with porous surface structure, which has an effective role for element diffusion so as to strengthen the interfacial adhesion rapidly, and a dense Al₂O₃ sublayer to suppress the interdiffusion was effectively used as diffusion barrier in this work and interdiffusion barrier ability was investigated. The AAO film was obtained by anodizing Al film deposited on C103 niobium alloy by vacuum evaporation technology, and an electroplating Ni plating was prepared as an overlayer. Vacuum heat treatment was applied to promote element diffusion. The results indicated that substantial diffusion occurred in the Ni/C103 specimen without an interlayer and in the Ni/Al/C103 specimen with Al film as an interlayer. In the Ni/AAO/C103 specimen, hardly any interdiffusion was observed. After 4 h vacuum annealing at 900 ℃, NbNi₃ phase was detected on the Ni/C103 and Ni/Al/C103 specimens, which could not be found in the Ni/AAO/C103 specimen. Nb content in the Ni overlayer of Ni/C103, Ni/Al/C103 and Ni/AAO/C103 specimens was 7.05%, 5.08% and 3.55%, respectively. Ni content in the substrate of Ni/C103, Ni/Al/C103 and Ni/AAO/C103 specimens diffusing from the overlayer was 6.84%, 3.62% and 2.85%, respectively. Thus, AAO film exhibited strong barrier ability in suppressing element diffusion. From calculation of the Fick's law, it was found that diffusion coefficient of Ni and Nb in the AAO film at 900 ℃ was 3.28×10^-14 m²/s and 2.16×10^-14 m²/s, respectively, and it was raised to 1.03×10^-13 m²/s and 3.58×10^-14 m²/s at 1000 ℃, respectively.