The Weibull Distribution of Microhardness in Plasma Sprayed NiCrAl/AT13 Nanostructured Ceramic Coating

摘要

Al_2O_3-13% TiO_2 based nanostructured ceramic coatings were prepared on the surface of NiCrAl alloy by Plasma Spraying technology. Compared to the micron ceramic coating (MCC), the average value of hardness of nanostructured ceramic coating (NCC) was much higher than that of MCC, and the NCC presents typical bi-modal distribution. The Weibull distribution of both coatings exhibited apparently dispersible, but NCC's was quite well-distributed. The relationship between microhardness and microstructure were analyzed through SEM, XRD and TEM. The results indicate that the microcracks of NCC are fine and the size of particles is small. The structure of NCC coatings contained more α- Al_2O_3 and TiO_2 and less γ-Al_2O_3 than that of MCC coatings. According to TEM analysis, it can be considered that the grain refinement, toughening of microcracks, and the dispersive refinement of Al_2O_3 nanoparticles on Al_2O_3-TiO_2 matrix are main mechanisms to improve the mechanical properties of NCC.