Influence of High Energy Atomic Oxygen Beam Flow on the Vacuum Tribological Properties of Ag-Cu Composite Film SUN Xiao-Jun, WANG Peng, HU Ming, WANG Bo, LIU Wei-Min (Institute of Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences) The key points of solid lubrication are the friction curves of thin films under different atomic oxygen irradiation conditions. The initial friction coefficient increased slightly after irradiation for 30 minutes, but decreased after the run-in period. After 1h of irradiation, the friction coefficient did not show a downward trend during the run-in period, and it increased until the failure of lubrication; the coefficient of friction of the film increased from 0.17*0.01 to 0.60, and the initial coefficient of friction increased from 0.25 to 0.300.40. After 30 minutes, the wear life of the film decreased by about 50%, and the lubricating performance was basically lost after 1 h of irradiation.

Effect of Atomic Oxygen Irradiation on the Friction Coefficient of the Film The influence of atomic oxygen irradiation on the critical load and mass of the film is the curve of the critical load of the film with the irradiation time. From the figure, it can be known that the critical load decreases with the irradiation time.

Since the critical load is related to the adhesion of the film, the adhesion of the film can be characterized by the critical load. The results show that atomic oxygen irradiation leads to a decrease in the adhesion of the film.

The SEM photograph of the surface of the wear scar before and after the film was irradiated with atomic oxygen. As shown in Fig. (a), the surface morphology of the wear scars before irradiation is relatively uniform. Figures (b), (c), and (d) are the wear scars of the film after 1, 2 and 3 h irradiation with atomic oxygen, respectively. In the appearance, obvious furrows appeared after 1h of irradiation; after 2h irradiation, the film was easily detached from the substrate during the rubbing process; after 3h of irradiation, continuous pits appeared on the surface of the worn surface of the film. The results showed that atomic oxygen irradiation led to a decrease in the wear resistance of the film.

2.2 chemical composition diagram. The effect of atomic oxygen irradiation on the chemical state of the Ag element in the film is the XPS depth analysis of the composition of the Ag-Cu composite film. From the graph analysis, the surface morphology of Ag 2.3 can be seen from (a) during the sputter etching process. In addition, the original surface morphology of the film is relatively uniform, but a certain number of "droplets" with a geometric dimension ranging from less than lm to several pm are distributed, which is due to poor filtration during ion plating film formation. After atomic oxygen irradiation, the reflective performance of the film on natural light is reduced, the surface loses metallic luster, the droplets gradually disappear, and the surface microstructure is coarsened, forming a loose network structure with craters.

2.4 Mechanism of Lubrication Failure The above analysis results show that high energy atomic oxygen beam irradiation has a significant effect on the vacuum tribological performance, chemical composition and surface morphology of ion-plated Ag-Cu composite films. Because the microstructure of the thin film is columnar, the grain boundary provides high-energy atomic oxygen to provide deep channels inside the thin film. The high-energy atomic oxygen beam with a kinetic energy of 5 eV can directly reach the depth of the thin film, resulting in severe oxidation of the film, and the oxidation reaction is The surface of the film and the inside of the film occur synchronously, and the oxides generated by irradiation of atomic oxygen on the inside of the film are entrapped in the film. During the friction process, when the film is subjected to a periodic load, it is easy to fall off from the substrate to generate abrasive wear, forming a concavity. The pits even expose the substrate, which causes the adhesion of the film to decrease, the friction coefficient to increase, and the wear life to decrease, resulting in degradation of the film's lubricating properties. The wear life of the film is reduced; in addition, the effective lubricating composition of the Ag-Cu film after atomic oxygen erosion is reduced, which is also one of the important factors that cause its lubrication failure.

Effect of Atomic Oxygen Irradiation on the Surface Morphology of Thin Films Conclusion The high energy atomic oxygen beam irradiation has a significant oxidation effect on the ion-plated Ag-Cu composite thin film, in which the valence of oxygen element increases as the irradiation dose increases, and oxidation occurs. The product is gradually changed from A0 to AgO in the initial stage of irradiation. High-energy atomic oxygen beam irradiation can enter the film and undergo deep oxidation reaction, resulting in reduced film adhesion, increased friction coefficient, shortened wear life, and vacuum tribological properties. Degradation.

The influence of high-energy atomic oxygen irradiation on the tribological properties of materials is an important issue involving the mechanical reliability of space. It is of great significance to China's national security, and it is also a frontier study of physics, chemistry, materials science and space. In the field, many urgent issues need to be based on breakthroughs, and it is therefore proposed to strengthen the display of progress in the intellectual property rights of the leader of the country.

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