Experimental Studies On Adhesion And Transferring Behavior Mechanisms Of Thermoplastic Composite On Dry-friction Sliding Interfaces

Carbon fiber/polyether-ether-ketone(CF/PEEK)thermoplastic composites,as a new type of carbon fiber composites,have many excellent properties compared with common carbon fiber/epoxy resin thermosetting composites,and have broad application prospects in aerospace and medical fields.However,due to the characteristics of high strength and high modulus,carbon fiber composite is a typical material difficult to machine,which causes serious wear and even damage to the cutting tool in the process of machining.Therefore,the selection of appropriate tools and materials is very important for reducing tool loss and improving the quality of machined parts.This paper focuses on the mechanism of tool-workpiece contact zone in CF/PEEK machining process,and studies the friction and wear mechanism of modified tool surface through friction and wear experiments,so as to provide support for the design of more reasonable tool.Four kinds of micro textures were designed on the surface of WC/Co cemented carbide by femtosecond laser to improve the friction and contact conditions of the substrate surface,and the structure size and processing defects of the textures were characterized and analyzed.Ti N,Ti Al N,DLC,diamond and other common hard coatings were deposited on YG6 substrate by magnetron sputtering,multi arc ion plating and CVD hot wire method,and the key physical properties of the coatings were tested and analyzed.The pin-disk friction experiment was designed and developed.The friction coefficient curves of WC/Co-CF/PEEK under different conditions were obtained by setting different sliding contact speeds and loads to reflect the actual production and processing conditions.The change of friction coefficient and the morphology of wear scar area were analyzed to explain the damage behavior of CF/PEEK to WC/Co substrate.Then,the softening and adhesion phenomenon of peek under high load and the strengthening and friction reducing effect of carbon fiber intervention on PEEK were revealed by PEEK and CF/PEEK friction experiments.The friction and wear experiments between CF/PEEK and various modified surfaces were carried out.The friction coefficient variation of different coatings and textures was analyzed.The friction and wear mechanism of different modified surfaces was revealed by micro-characterization and element transfer in the contact zone of wear marks.The results show that the Ti N and Ti Al N coatings will have serious adhesion with PEEK,which will lead to the temperature rise in the contact area and even overheating oxidation;DLC coating has very low friction coefficient,and almost no debris bonding occurs;diamond coating has a lot of debris and adheres to the coating surface during the friction and wear process because of its high hardness and surface grain characteristics.Texture can reduce the friction coefficient of WC/Co by 50% at most,but the Heat-Affected zone formed by laser texturing can reduce the adhesion between coating and substrate.