Lubrication Properties of MoS₂ Coatings Co-Doped with Ti and Al

The Al-Ti co-doped MoS₂ composite coatings,deposited by RF/DC magnetron sputtering of MoS₂,Al and Ti targets,were annealed in argon atmosphere.The influence of the doping mode of Al(RF or DC sputtering) and annealing on the lubrication behavior of Al-Ti/MoS₂ coatings was investigated with X-ray diffraction,scanning electron microscopy,energy dispersive spectroscopy and mechanical probes.The results show that the Al-doping mode and annealing had a major impact.For instance,RF-Al-Ti/MoS₂ coating,with an S/Mo atomic ratio of 1.55,considerably outperforms DC-Al-Ti/MoS₂ coating,because of higher deposition-rate,more compactness,greater thickness,easier MoS₂ grain formation,much lower friction-coefficient(~0.1),accompanied by stronger oxidation/wear resistances originated from higher Al-content.An annealing at 500℃ decreased the average friction coefficients of both RF-and DC-Al-Ti/MoS₂ coatings to 0.08 and 0.07,respectively.