| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 102 === This thesis studies the mechanical and tribological properties of tungsten-doped carbon nitride coating deposited by unbalanced DC magnetron sputtering using nitrogen-argon mixture gas. We first deposited the carbon nitrite coating on three different types of interlayer—Ti, Ti/TiN, and Ti/TiC—and chose the interlayer with the best tribological properties as the basis to study the optimal coating parameters (the tungsten target current varied from 0 to 0.9 A.). For the mechanical properties, we measured the surface morphology with roughness testing and scanning electron microscopy, analyzed the chemical composition and depth profile with X-ray diffraction analysis, Raman spectroscopy, and glow discharge spectroscopy, and tested the hardness and elasticity with nano-indentation and Rockwell indentation test; for the tribological properties, we tested properties of self-lubrication and the wear life with a pin-on-disk tribometer. With the optimal parameters, we finally coated the tungsten-doped carbon nitride on commercial tuning inserts and micro-drillers and analyzed its impact on cutting performance and tool life by cutting and drilling test. The results show all the coatings are amorphous, with thickness around 1.5 µm. These coatings contain nitrogen approximately 30 at% and tungsten 0-9 at%; the hardness ranges from 15 to 20 GPa. In particular, the wear resistance correlates well with the indentation adhesion level, but the hardness correlates little with the tungsten content. Moreover, the coating deposited on Ti/TiC interlayer has greater adhesion. These coatings have low friction coefficient (0.01-0.3) and little wear coefficient (10-6 mm3/Nm): in the cutting test, the CN/TiC coating reduced 41% and 43% of flank wear of turning inserts and micro-drillers, respectively.
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