Effects of Processing Parameters on Microstructure and Properties of Nanoscale ZrC/ZrB2 Multilayered Coatings
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Abstract
ZrC/ZrB2 multilayered coatings with bilayer periods of 3.5--40nm are synthesized by rf magnetron sputtering. Analyses of x-ray diffraction, scanning electron microscopy and nanoindentation indicate that multilayered coatings possess much higher hardness and greater fracture resistance than monolithic ZrC and ZrB2 coatings. A maximum hardness (41.7GPa) and a critical fracture load (73.7mN) are observed in the multilayer with La=32nm deposited at the substrate bias -40V. Higher residual stress built in the ZrC layer can be released by periodic insertion of ZrB2 into the ZrC layer. A clear multilayered structure with mixed ZrB2 (001), ZrB2 (002) and ZrC (111) orientations should be responsible for the enhanced mechanical properties.
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