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Four kinds of ZrC coatings with nearly the same thickness have been successfully prepared on graphite substrate by chemical vapor deposition(CVD) through controlling the ratio of inlet reacting gases.From backscat-tered electron images,it can be inferred that ZrCⅢcoating has the best tightness of all coatings.Meanwhile,line energy spectrum curve shows that zirconium and carbon elements distribute uniformly along the normal direction of the ZrCⅢcoating.As for varied microstructures,the coatings show different mechanical properties and residue stress.The strength and elastic modulus of ZrCⅢcoating were up to 89.57 and 1192.5 GPa,respectively.Those make it near the level of diamond.Value of residue tensile stress of ZrC+C composite coating was only 7.729 MPa and that of ZrCⅢcoatings was 349.632 MPa.The strong combination of small-size grains in ZrCⅢcoating plays a decisive role to the best mechanical properties.However,strong misfit of lattice between ZrCⅢcoating and substrate can induce high residue stress.
Four kinds of ZrC coatings with nearly the same thickness have been successfully prepared on graphite substrates by chemical vapor deposition (CVD) through controlling the ratio of inlet sponsors gases. From backscat-tered electron images, it can be inferred that ZrC III coating has the best tightness of all coatings. While the line energy spectrum curve shows that zirconium and carbon elements distribute uniformly along the normal direction of the ZrC III coating. As for the varied microstructures, the coatings show different mechanical properties and residue stress. The strength and elastic modulus of ZrC III coating were up to 89.57 and 1192.5 GPa, respectively.Those make it near the level of diamond. Value of residue tensile stress of ZrC + C composite coating was only 7.729 MPa and that of ZrCⅢcoatings was 349.632 MPa. The strong combination of small-size grains in ZrCⅢcoating plays a decisive role to the best mechanical properties. However, strong misfit of lattices between ZrCⅢcoating and substrate can induce high residue stress.