Microstructure Characteristic and Properties of Plasma Sprayed NiCoCrAlY-Al2O3-ZrO2 Gradient Coating on Mg Alloy

作者：Chen Yan; Weng Zhiping; Lu Sheng^*; Wang Zexin; Chen Jing; Lai Huaqing

来源：Rare Metal Materials and Engineering, 2013, 42: 46-49.

• magnesium alloy
• plasma spraying
• microstructure
• property
• gradient coating

NiCoCrAlY-Al2O3-ZrO2 gradient coating was fabricated on AZ91D Mg alloy substrate by plasma spraying with NiCoCrAlY/Al2O3-ZrO2 double layer coating as reference. The microstructures of the coatings were investigated by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) while the bonding strength, thermal shocking resistance and corrosion resistance were evaluated by tensile, thermal shocking and electrochemistry experiments. The results reveal that compared with NiCoCrAlY/Al2O3-ZrO2 double layer coating, NiCoCrAlY-Al2O3-ZrO2 gradient coating is characterized with more compact layer and layer interfaces as well as fewer microcracks and porosities. Thus both the bonding strength and thermal shock cycle numbers of the gradient coating (45.8 MPa, 320) are higher than those of double layer coating (32.5 MPa, 186). With corrosion current of 1.531 x 10(-7) A, which descended two orders of magnitude, the corrosion resistance of the gradient coating is better than that of double layer coating. It indicates that the design of the gradient coating is of help to relieve thermal stress and slow down the crack formation and crack propagation rate. The gradient coating is mainly broken between substrate and bonding layer due to thermally grown oxides in the NiCoCrAlY bonding layer and thermal stress accumulated during thermal cycles.

• 出版日期2013-11
• 单位江苏科技大学