Preparation And Tribological Properties Of Carbon-based Composites

With the development of economy and the progress of science and technology,machinery,aerospace and nuclear industries have occupied the dominant position of industry.And in these areas,the inevitable friction results in excessive use of lubricants,which exacerbated the energy crisis and environmental pollution problems.In order to keep sustainably developing of resources and environment,the research of green and sustainable lubrication system has become particularly important.One aspect is the choices of lubricants.We can choose water-based lubricant instead of oily lubrication,which has been in a various use of metal processing field due to for the wide source and low cost of water-based lubrication.Thus,we need to explore highly efficient and reliable green additives to promote the application of water-based lubrication.The other aspect is solid lubrication.If the material itself has lubricating effect,it will greatly reduce the waste of resources.In the field of solid lubrication,carbon materials and polymers have a wide range of applications.In this paper,the tribological behavior of carbon materials as water-based lubricating additives and the tribological behavior of carbon materials as polymer self-lubricating composites were studied,in order to explore the green and sustainable lubrication system.The primary contents and results are listed as follows:(1)The graphene oxide(GO)is prepared by the modified Hummers method,and the multi-walled carbon nanotubes are acidified(MWCNTs-COOH).The prepared GO and MWCNTs-COOH are compounded by solution hybrids vacuum filtration to prepare GO/MWCNTs-COOH hybrids.The friction and wear behavior of GO/MWCNTs-COOH hybrids with different proportions as water-based lubricating additives were studied.It was found that the best ratio of GO: MWCNTs-COOH is 3:1,and the ?-? noncovalent bond between GO and MWCNTs-COOH forms a uniform network intercalation structure,which make sure the hybrids can be stably dispersed in aqueous solution.GO/MWCNTs-COOH hybrids have a synergistic effect under the cyclic friction,whose tribological performance is superior to the same content of GO and MWCNTs-COOH separately as water-based lubricating additives.(2)Adding the GO/CNTs hybrids prepared by the solution hybrids vacuum filtration method into the polyimide(PI)matrix as fillers to get GO/CNTs/PI composites via in-situ polymerization.The results show that the GO/CNTs/PI composites have excellent mechanical properties and thermal properties,and significant self-lubricating effect.Under dry friction condition,the PI matrix with GO/CNTs hybrids has much lower friction coefficient and wear rates than those of pure PI matrix.Similarly,the friction and wear behavior of GO/CNTs/PI composites is better than the friction properties of pure polyimide in the presence of water-lubricated media.(3)PI/poly(vinylidene fluoride)(PVDF)composites and carbon fiber(CF)/PI/PVDF composites are prepared by cold-pressing sintering,and their mechanical,thermal and tribological properties are studied.Studies have shown that PVDF is a soft phase,both mechanical and tribological properties of PVDF matrix have been enhanced after filled by PI and CF.The friction coefficient of PVDF is very low,but the wear rates are very high.The addition of PI and CF can significantly improve the phenomenon.This study has a potential research value in the field of solid lubrication.