X. H. LIANG, K. S. ZHOU, M. LIU, R. J. HONG, C. G. DENG, Guangzhou Research Institute of Non-ferrous Metals, Guangzhou, China
Abstract: The NiCoCrAlYTa coating was prepared on Ni-base single crystal super-alloys by low pressure plasma spraying(LPPS). Oxidation kinetics and oxidation mechanisms of coating at 900CA1000CA1100C were studied. The oxide scale and surface morphology of NiCoCrAlYTa coating were investigated by means of XRD and SEM.The result shows that there are different oxidation dynamical regulars at the above three different temperature. The oxidation kinetics of NiCoCrAlYTa coating follows cubical equations at 1100C, parabola equations at 1000C,and logarithmic equations at 900C. θ|Al2O3 and a-Al2O3 as protective oxide scale were formed on the surface of the NiCoCrAlYTa coatings after 200 hours oxidation at three different temperature. According to the experimental results,θ|Al2O3 oxide scale activation energy is 151.78kJ/mol and a-Al2O3 oxide scale activation energy is 270.25kJ/mol
Summary: IN turbine, The NiCoCrAlYTa coating produced by low pressure plasma spraying was used to improve the capability of substrate that resists oxidation and corroding at high temperature. At the beginning of turbine working, the vanes of turbine will come through different temperature from room temperature to above 1100J. After some hours,cAl2O3 and -Al2O3 as protective oxide scale were formed on the surface of the NiCoCrAlYTa coatings. According to the experimental results, we found that there are different oxidation dynamical regulars at the different temperature of 900JB1000JB1100J. It isnt complete according with the parabola equations that is familiar. We also have calculated the activation energy of cAl2O3 oxide scale and -Al2O3 oxide scale by modeling.
