Deposition and characterization of hard-solid lubricant coating by closed-field magnetron sputtering

Thin hard coatings (i.e., TiN, CrN, TiAlN etc.) have been widely accepted particularly in the cutting and forming tool industries. But many of these coatings have higher co-efficient of friction, which does not protect the opposing surface and sometimes in a closed system, the eroded hard coating particles act like grits which propagate the failure of the coatings before the expected time. Recently, hard-solid lubricating coating has been investigated to lower the wear rate and coefficient of friction by the combined effect of soft and hard phases. In the present investigation, TiN + MoSx hard-solid lubricant coating was deposited by closed-field magnetron sputtering from separate Ti and MoS2 target in a N2 gas environment. EDX analysis showed different weight percentages of Mo + S in the TiN + MoSx coatings deposited with different MoSx target currents. In the XRD study, peaks shifting to lower angles compared to pure TiN indicated the incorporation of Mo and S atoms in the TiN matrix. Adhesion was also improved in the TiN + MoSx coatings. Pin-on-disk measurements at normal atmospheric condition against WC ball showed much lower wear and coefficient of friction compared to pure TiN coating.