CrN中间层阻挡元素扩散的能力研究

Interdiffusion Barrier Ability of CrN Interlayer at High Temperature

为了降低涂层和基体间的元素互扩散,采用电弧离子镀技术在NiCrAlY防护涂层和DSM11基体间加入CrN扩散阻挡层。用扫描电镜(SEM)观察了沉积态CrN涂层、退火和氧化态NiCrAlY/DSM11和NiCrAlY/CrN/DSM11的表面和截面形貌;通过能谱(EDS)分析了元素沿防护涂层和扩散阻挡层的截面分布;用X射线衍射仪(XRD)检测了防护涂层和扩散阻挡层的物相结构;用透射电镜(TEM)观察了样品退火和氧化后扩散阻挡层的形貌特征;利用1100℃恒温氧化实验比较了单一NiCrAlY涂层和NiCrAlY/CrN涂层体系的抗氧化能力,结合真空扩散实验分析了高温情况下元素在涂层和基体间的扩散。结果表明:CrN扩散阻挡层能有效地抑制合金元素的互扩散。其原因与高温下CrN→Cr2N→TiN的转变有关;TiN在扩散阻挡层的生成有利于防护涂层抗氧化能力的提高。

In order to suppress the element interdiffusion,the CrN interlayer was introduced as a diffusion barrier into the NiCrAlY/DSM11 interface by arc ion plating （AIP） technique. The morphologies of the as-deposited CrN,the annealed and thermally exposed NiCrAlY/DSM11 and NiCrAlY/CrN/DSM11 were observed by scanning electron microscope （SEM）. With the aid of energy-dispersive spectra （EDS）,the element distribution was studied along the cross-section of the specimens. The phase structures of the overlayer and diffusion barrier were analyzed by X-ray diffraction （XRD）. The morphologies of the diffusion barriers were observed by transmission electron microscope （TEM） in the annealed and exposed NiCrAlY/CrN/DSM11. The oxidation-resistance of the single NiCrAlY coating and NiCrAlY/CrN duplex coating was investigated after thermal exposure at 1100℃ in air and the ability was evaluated of the CrN diffusion barrier to suppress element interdiffusion at high temperature. The results show that the NiCrAlY/CrN coating system provides more effective protection for the substrate than the single NiCrAlY coating and the diffusion barrier effectively decreases the element interdiffusion,which is attributed to the chemical reaction of CrN→Cr2N→TiN in the diffusion barrier during vacuum annealing and thermal exposure.