Degradation behaviour of sputtered Co-Al coatings on superalloy

作者：Rahman Atikur; Chawla Vipin; Jayaganthan R^*; Chandra Ramesh; Ambardar R

来源：Materials Chemistry and Physics, 2013, 138(1): 49-62.

DOI：10.1016/j.matchemphys.2012.11.004

• Coatings
• Atomic force microscopy (AFM)
• Thermogravimetric analysis (TGA)
• Corrosion

Degradation behaviour of sputtered Co-Al coatings on Superni-718 substrate has been investigated. Cyclic high temperature oxidation tests were conducted on uncoated and coated samples at peak temperatures of 900 degrees C for up to 100 thermal cycles between the peak and room temperatures. The results showed that a dense scale formed on the coated samples during thermal cycling at the peak temperature of 900 degrees C. The external scale exhibited good spallation resistance during cyclic oxidation testing at both temperatures. The improvement in oxide scale spallation resistance is believed to be related to the fine-grained structure of the coating. Nanostructured Co-Al coatings on Superni-718 substrate were deposited by DC/RF magnetron sputtering. FE-SEM/EDS, AFM, and XRD were used to characterize the morphology and formation of different phases in the coatings, respectively. The Co-Al coating on superalloy substrate showed better performance of cyclic high temperature oxidation resistance due to its possession of beta-CoAl phase as Al reservoir and the formation of Al2O3 and spinel phases such as CoCr2O4 and CoAl2O4 in scale. The oxidation results confirmed an improved oxidation resistance of the Co-Al coating on superalloy as compare to bare substrate in air at 900 degrees C temperature up to 100 cycles.

• 出版日期2013-2-15