Effect of CH 4 flow rate on the microstructure and tribological behavior of Ti/W-C/W-DLC gradient coatings on YG12 cemented carbide

To protect WC-Co tools during machining, Ti/W-C/W-DLC compositionally graded coatings were deposited on YG12 cemented carbide via reactive magnetron sputtering. The effect of CH 4 flow rate (20–40 sccm) was systematically investigated. Results show a 30 sccm flow yields an optimized, dense sp 3 -rich amorphous structure with the lowest I D /I G ratio (0.82), suppressing W-catalyzed graphitization. This coating exhibits superior resistance to mechanical deformation and the highest interfacial adhesion (L c1 = 22 N). Furthermore, tribological tests demonstrate a low friction coefficient (∼0.09) and minimum wear rate (1.7 × 10 –7 mm 3 ·N −1 ·m −1 ). These findings elucidate hydrocarbon kinetics, providing a structural design strategy for highly wear-resistant cutting tools.