| With the rapid development of aerospace technology,the demand for high precision and long life oil bearing is becoming more and more urgent.At present,the bearings of the domestic navigation system often fail after the end of spaceflight.The basic reason is that the supply of lubricant is insufficient.The gyroscope bearing is lubricated by its porous oil holder.The oil-bearing material itself has a complex porous structure,in which lubricants can be stored.When the bearings are in normal operation,the lubricating oil can be continuously released,and a stable lubricating film is formed on the friction surface.This dissertation tries to make full use of the advantages of porous self-lubricating materials;we apply it into the bearing holder of the navigator and improve its properties according to the requirements of the bearing cage.According to the special working environment of the bearing cage,we select polyimide as matrix material as a result of its excellent performance.The porous oil material is prepared by cold pressing and sintering process,and in order to increase its porosity,we add pore forming agent in the matrix material.The properties of porous materials are dramatically affected by the process parameters.In the preparation process,it is mainly affected by four factors and every factor has numerous levels.In order to solve this problem,this dissertation designs an orthogonal experimental design method and the experimental results are analyzed and processed.Finally,the main parameters affecting the performance of porous oil materials are obtained and then we determine the optimal scheme.Eventually,the correctness of the parameters of the preparation process was tested by mercury porosimetry and we got the method for preparing novel oil storage material.In order to improve the mechanical properties and oil-bearing property of porous materials,in this paper,carbon nanotubes were used as additives to improve the oil content,oil retention and mechanical properties of porous materials by take advantage of the its strengthening and toughening mechanism and high surface energy.The effects of the content and type of carbon nanotubes on the properties of porous materials were studied in this dissertation.And we observed the porous oil-bearing material by scanning electron microscopy(SEM).The surface morphology,pore characteristics and wear scar morphology of porous materials were observed and analyzed and the mechanism of friction and wear is discussed too.Considering that the performance of lubricating oil is insufficient when used in high temperature,low temperature,vacuum,strong radiation and high speed motion,in this paper,a new method is proposed to improve the friction and wear properties of self-lubricating materials.That is oil and solid composite lubrication technology.This paper mainly studied the lubricating oil and solid lubricant composite filling polyimide,and explored mechanism of synergistic effect of lubricating oil and solid lubricating film.The lubrication model of oil solid composite to improve wear is established and verified.The mechanism of oil solid composite lubrication is obtained: when the lubricant fails or does not supply enough to form a complete lubricant film,the solid lubricant film on the surface of the material can provide additional lubrication. |
