Tribologocal Behaviors Of Silver-based Composites With Low Friction

The Space slip-rings is used to realize the transmission of electric power and electric signal between spacecraft mechanisms.It is the core component of the spacecraft energy and load system,and it is also the easy-to-wear component.The development of long-life and low-wear space current-carrying friction materials is of great significance to the improvement of spacecraft’s comprehensive service performance.In this paper,Ag-WS₂composite material is used as the research object to study the influence mechanism of its lubricating phase size on the mechanical properties and tribological behavior of the material,and the concept of dual-phase lubrication is introduced to explore the current-carrying friction behavior characteristics of Ag-WS₂-Mo S₂composite material and anti-friction and wear-resistant mechanism,and finally carry out the research on the friction matching characteristics of silver alloy fiber brushes to the silver-based solid lubricating composite ring body,clarify the current-carrying friction characteristics of this type of contact,and provide a theoretical basis for related application fields.The main research results of this article are as follows:（1）The mechanism of the influence of WS₂scale on the friction and wear properties of Ag-WS₂composites is revealed.Studies have found that small particle size WS₂is easy to fill the gap structure of the roughness grooves or micro-protrusions of the wear surface,and it is more helpful for the wear interface to form a continuous and smooth lubricating film,thereby obtaining low and stable friction behavior.With the reduction of the WS₂scale from 6μm to 80 nm,the wear surface of Ag-WS₂composite material becomes smoother,the roughness of the wear surface decreases from 3.31μm to 1.66μm;the content of WS₂on the wear surface increases from 46.83 wt.%to 51.48 wt.%,the friction coefficient is reduced from 0.21 to 0.09;the wear rate is also reduced from 4.68×10^-5mm³/N·m to 3.35×10^-5mm³/N·m.（2）The effects of environment on the friction and wear properties and electrical contact properties of Ag-WS₂-Mo S₂composites were investigated.Studies have shown that the vacuum current-carrying friction performance of the Ag-WS₂-Mo S₂composite material is better than that of the atmospheric environment.When the sliding speed in the vacuum environment is 0.1 m/s,the thickness of the lubricating film is more than 140 nm,showing good contact stability The friction coefficient is as low as 0.121,the wear rate is 2.53×10^-6mm³/N·m,the contact resistance is 3.47 mΩ,and the electrical noise is only 0.39 mΩ.（3）By comparing the friction matching of silver alloy fiber brushes with five groups of ring materials,it is clearly found that Ag Cu10,Ag Cu Ti-WS₂and Ag-WS₂-Mo S₂have good friction matching with Ag Cu Ni fiber brushes;under the action of electric current,The friction coefficient of Ag Cu10 is generally greater than 0.4,the contact resistance is 44.62 mΩ,;the friction coefficients of Ag Cu Ti-WS₂and Ag-WS₂-Mo S₂are 0.31 and 0.21,respectively,and the contact resistance is 47.81 mΩand 59.21 mΩ,respectively.（4）The influence of rotating speed on the friction coefficient,contact resistance and electrical noise of the preferred pair Ag Cu Ni/Ag-WS₂-Mo S₂was studied.Studies have shown that reducing the sliding speed can significantly improve the electrical contact performance of the Ag Cu Ni/Ag-WS₂-Mo S₂pair;but the friction coefficient between the pair increases with the decrease of the speed.The Ag Cu Ni/Ag-WS₂-Mo S₂pair has the lowest friction coefficient（0.21）at a speed of 100 rpm,and the lowest contact voltage drop（44.52 mΩ）and electrical noise（7.16 mΩ）at a speed of 2 rpm.Figures 42,tables 7,references 87...