Plasma Sprayed Dense MgO-Y_2O_3 Nanocomposite Coatings Using Sol-Gel Combustion Synthesized Powder

摘要

MgO-Y_2O_3 nanostructured composite powder (volume ratio of 50:50) was synthesized by a sol-gel combustion process which generated crystal sizes in the 10-20 nm range. The MgO-Y_2O_3 nanopowder was plasma sprayed using a conventional, DC arc plasma spray system. X-ray diffraction analysis shows that the as-sprayed MgO-Y_2O_3 coating is composed of cubic MgO and Y_2O_3 phases and has ～95% density. Microstructure characterization by SEM reveals that the as-sprayed coating has fine grain sizes of 100-300 nm as a result of rapid solidification. The hardness of the coating, 7.5 ± 0.6 GPa, is higher than that of coarse-grained, dense MgO, and Y_2O_3 ceramics. This approach demonstrates the potential of plasma spray processes for making thick, dense MgO-Y_2O_3 nanocomposite performs for applications as durable, infrared windows.