| The rapid development of modern industries such as aerospace,machining and automobile manufacturing has been putting forward higher requirements for the reliability and wear resistance of mechanical transmission parts.Epoxy resin(EP)is widely used as bearings,seals,gears and other parts due to their light weight,excellent mechanical properties and stable chemical properties.However,EP has low glass transition temperature(T_g).Under frictional or high-temperature extreme environments,local heat accumulates and polymer chains are prone to migrate,which often cause material creep,deterioration of mechanical properties,and aggravation of friction and wear.Based on this,a new type of carbon nanocage(CNC)material was prepared as EP filler,which enhances the mechanical properties of EP and inhibits its creep by using its physical confinement for EP in the cage,dimensional effect(i.e.,one-dimensional rod-like,two-dimensional flake-like and three-dimensional ball-like CNC assemblies)and its storage function on ionic liquid,respectively.The friction and wear properties are further improved by solid-liquid composite lubrication at room temperature and high temperatures.The specific research content and results are summarized as follows:(1)CNC with hollow cubic structure was prepared by template method and used as EP filler to obtain CNC/EP composites.The results show that EP monomer can enter the CNC cavity.After optimizing the content of filler,it is found that the composite has the smallest coefficient of friction and wear rate when the CNC content is 0.25 wt%,which are reduced by 55.6%and 51.9%compared with EP,respectively.This is mainly due to the physical limitations of CNC's unique cage structure.The thermal creep of EP can not only be restricted by the physical constraints of the cage wall,but also can be used as a self-lubricating material.In addition,the cage cavity also has the function of collecting wear debris,which can promote the formation of transfer film.Overall,the unique CNC integrates multiple functions to constrain creep,reduce friction and wear,and collect wear debris.(2)CNC assemblies with different dimensions(One,two and three dimensions)were prepared by template method as EP filler,and corresponding CNC/EP composites were obtained.High temperature friction tests were carried out on the composites.The results show that the composites prepared by one-dimensional CNC assembly have the best high temperature lubrication properties compared with other CNC assemblies.The friction mechanism is as follows:the one-dimensional CNC assembly packing is easy to form a strong cross network in the process of dispersing in the matrix,which plays a better spatial limiting role on the EP matrix,and it can move in a rolling way in the transfer film softened by high temperature while bearing the load,thus reducing friction and wear.(3)A CNC cavity was filled with Ionic Liquid(IL)by vacuum-assisted method to form a self-lubricating carbon capsule.The corresponding EP matrix composites were obtained without affecting the curing effect.The friction results show that when the content of CNC and IL was 0.10 wt%and 0.5 m L,the friction coefficient and wear rate reach the lowest,which decrease by 54.54%and 32.36%compared with EP,respectively.The friction mechanism is as follows:first,CNC is damaged under the action of friction,and IL flows from CNC to the friction surface to form a solid-liquid lubrication film;secondly,IL is coated on CNC surface after outflow,forming slip layer between each other;finally,the friction counter steel ball surface can also form a new slip layer through IL. |
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