等离子喷涂NiCrAl/ZrO_2过渡层对FeCrAl/γ-Al_2O_3结合性能的影响

Influence of plasma-sprayed NiCrAl/ZrO_2 intermediate on adhesion of FeCrAl/γ-Al_2O_3

为改善催化剂中 γ-Al2 O3 分散层与 Fe Cr Al基体的结合力 ,采用等离子喷涂技术在合金表面制备了 Ni Cr Al/Zr O2 混合涂层作为过渡层。利用 X射线衍射仪、扫描电镜和电子探针仪 ,研究了 10 73 K氧化后过渡层的变化 ,并考察了超声振动和热冲击后涂层的剥落情况。结果表明 ,过渡层表面相主要是 Ni和 Zr O2 ;内部组织包括喷涂材料层、氧化物夹杂、孔洞及未熔融颗粒 ;与基体为冶金结合。随着高温氧化时间增加 ,过渡层表面 Ni O晶粒增多并长大 ;内部发生了合金元素互扩散 ;界面处 Ni,Al含量明显增加。这种表面预处理形成了粗糙多孔的过渡层 ,提高了氧化铝分散层与金属基体的粘结力 。

A NiCrAl/ZrO 2 intermediate was deposited on the surface of FeCrAl by plasma spraying to improve the adhesion of a γ Al 2O 3 washcoat on the FeCrAl substrate in auto catalysts. The coating was analyzed by XRD, SEM, and EADX and weight loss after ultrasonic vibration and thermal shock was also examined. The surface phases of the sprayed coating were mainly Ni and ZrO 2. The sprayed coating included oxide impurities, micro pores and nonfusible particles and was metallurgically combined with the substrate. Increasing oxidation time increased the NiO crystal size. Alloying elements diffused between the coating and the substrate with a high level of Ni and Al concentrated at the interface. The plasma spraying pretreatment formed a coarse intermediate coating, which resulted in enhanced adhesive strength between the washcoat and the substrate and reduced the thermal stresses at the interface.