Performance Study Of Nickel-based Wide Temperature Range Lubricating Films Prepared By Magnetron Sputtering On GH4169 Surface

The existences of friction and wear in various assembly equipment not only reduce the energy transmission efficiency,but also significantly affect the service life of key components.The most commonly used method for reducing friction and consumption in engineering is oil lubrication.However,the liquid lubricant will quickly degrade and fail in high temperature environment.Under these circumstances,solid lubrication is the best choice to improve the tribological performance.Actually,especially in aerospace,the parts are usually used in a wide temperature range.It is great significance to provide a solid lubricant which has excellent lubricating performance in wide range temperature.However,few researches have been carried out in this field.In this paper,NiCrAlY/Ag and NiCrAlY/Ag/MoS₂ composite films were prepared on GH4169 superalloy by magnetron sputtering technology.The effects of deposition temperature,MoS₂ and Ag contents on the structure and tribological properties at different temperatures of the composite films were investigated.The surface morphologies,cross-sectional morphologies and phase structures of the films were analyzed by scanning electron microscopy?SEM?and X-ray diffraction?XRD?.The hardness and adhesion strength of the films were analyzed by micro Vickers hardness tester and Rockwell hardness tester.The tribological properties of the films at different temperatures were analyzed by friction and wear testing machine.The main findings of the paper are as follows.?1?The deposition temperature has little effect on the hardness of the NiCrAlY/Ag composite films which at the range of 355.7-382.5 HV.With the increase of the deposition temperature,the columnar crystal of the films grow which leads to the decrease of the adhesion strength and the tribological properties.The adhesion strength level of the films decreased from HF1 to HF4.The composite films deposited at temperature of 60 ? have the best comprehensive performance.?2?With the increase of Ag content in NiCrAlY/Ag composite films,the Ni₃Al grains and columnar crystal are refined,and the adhesion strength level of the films are improved to HF1.When the Ag content increases to 25.78 at.%,the friction coefficients and wear rates of the films are 0.33,0.32 and 3.5×10^-5 mm3·N-1·m^-1,3.6 × 10^-5 mm³·N-1·m^-1 at 300 ? and 500 ?,respectively.?3?The deposition temperature has a significant effect on the structure of the NiCrAlY/Ag/MoS₂ composite films.When the deposition temperature at 180 ?,the surface shows the densest structure,the adhesion strength level of film reaches to HF1,and the film shows the best tribological performance.?4?With the increase of MoS₂ content in NiCrAlY/Ag/MoS₂ composite films,the structure become loose,the Ni₃ Al and Ag grains of the films are refined,and the adhesion strength level of the films increase from HF3 to HF1.However,it shows slightly effect on the microhardness of the composite films.The presence of MoS₂ improves the tribological performance of the films.The friction coefficients and wear rates of the films with Ag content is 10.21 at.% and MoS₂ content is 48.55 at.% are 0.43,0.43 and 3.6×10^-5 mm³·N-1·m^-1,3.1×10^-5 mm³·N-1·m^-1 at 25 ? and 300 ?,respectively.?5?With the increase of Ag content,the columnar crystal structure of the NiCrAlY/Ag/MoS₂ composite films become denser and the adhesion strength improved.When the Ag content is 17.14 at.% and MoS₂ content is 20.90 at.% in the composite films,the particle size of film is the smallest,the density is the highest,and the tribological performance is the best.The friction coefficients and wear rates at 25 ?,300 ?,500 ?,700 ? are 0.69,0.45,0.44,0.36 and 9.1×10^-5 mm³·N-1·m^-1,0.83×10^-5 mm³·N-1·m^-1,3.6×10^-5 mm³·N-1·m^-1,1.3×10^-5 mm³·N-1·m^-1 respectively.When the friction temperature at 500 ?,the lubricating phase silver molybdate is formed in the wear scar.