Isothermal and dynamic oxidation behaviour of Mo–W doped carbon-based coating

•The oxidation behaviour of Mo–W–C and DLC(Cr/Cr–WC/W:C–H/a:C–H) coatings is investigated at 400–1000°C.•Mo–W–C coating resists oxidation up to ∼800°C during thermo-gravimetric analysis.•DLC(Cr/Cr–WC/W:C–H/a:C–H) coating delaminates beyond ∼380°C during thermo-gravimetric analysis.•Mo–W–C coating initially oxidises at 500°C during isothermal oxidation test.•Local delamination of DLC(Cr/Cr–WC/W:C–H/a:C–H) coating exposes the substrate at 500°C during isothermal oxidation test. The oxidation behaviour of Mo–W doped carbon-based coating (Mo–W–C) is investigated in elevated temperature (400–1000°C). Strong metallurgical bond between Mo–W–C coating and substrate prevents any sort of delamination during heat-treatment. Isothermal oxidation tests show initial growth of metal oxides at 500°C, however graphitic nature of the as-deposited coating is preserved. The oxidation progresses with further rise in temperature and the substrate is eventually exposed at 700°C. The performance of Mo–W–C coating is compared with a state-of-the-art DLC(Cr/Cr–WC/W:C–H/a:C–H) coating, which shows preliminary oxidation at 400°C and local delamination of the coating at 500°C leading to substrate exposure. The graphitisation starts at 400°C and the diamond-like structure is completely converted into the graphite-like structure at 500°C. Dynamic oxidation behaviour of both the coatings is investigated using Thermo-gravimetric analysis carried out with a slow heating rate of 1°C/min from ambient temperature to 1000°C. Mo–W–C coating resists oxidation up to ∼800°C whereas delamination of DLC(Cr/Cr–WC/W:C–H/a:C–H) coating is observed beyond ∼380°C. In summary, Mo–W–C coating provides improved oxidation resistance at elevated temperature compared to DLC(Cr/Cr–WC/W:C–H/a:C–H) coating.