| With the rapid development of science and technology, polymer matrixcomposites have been widely used in various fields and their service conditionsbecome increasingly harsh, such as high speed, heavy load, high temperature andapplied fields, etc. Therefore, high performance of the polymer composites areincreasingly demanded. Some weak physical and, chemical effects have becomemore significant for the change of the service conditions and must be re-examinednow, which usually could be neglected because the role of these effects were not soobvious. The interfacial physical, chemical effects during friction will affect thetribological properties of the system, and also affect the operation stability,accuracy and service life of the components. Consequently, it is very necessary toinvestigate the interfacial physical, chemical effects and their influence on thetribological properties of the friction pair.In this thesis, the effects of friction condition, type and content of the fillerson the friction induced magnetization of the polymer composites containingferromagnetic fillers were mainly studied. The relations between friction inducedmagnetization and tribological behaviors were analyzed. It is expected that theresults could provide some theoretical basis for the optimization design and controlof the tribological properties of the system. This study has very good theoreticaland practical significance.In the research, three ferromagnetic powders–iron powder (Fe), cobaltpowder (Co), nickel powder (Ni)–were selected as fillers to prepare the PTFEcomposites. The friction induced magnetization effects as well as tribologicalproperties were examed using a face-to-face tribometer under different speeds andloads. Under our experimental conditions, some results are as follows:1. Friction induced magnetization generated during friction of PTFEcomposites containing ferromagnetic fillers (Fe, Co or Ni).2. The effects of load on friction induced magnetization were that: the frictioninduced magnetic inductions of15Fe and15Ni composites all increased slowly with the increase of the load. However, the friction induced magnetic induction of15Co composite was almost not affected by the load.The effects of running speed on friction induced magnetization were that:, thefriction induced magnetic inductions of15Fe and15Co composites became smallerand smaller with the increase of the load, while the friction induced magneticinduction of15Ni increased slightly.The effects of ferromagnetic filler content on friction induced magnetizationwere that:, the friction induced magnetization exhibited a increasing trend with theincrease of filler content.3. The friction induced magnetic induction had an impact on the tribologicalproperties of the composites, there are some laws as follows: with the increase ofthe friction induced magnetic induction, the friction coefficients of all compositesslightly lowered.With the increase of the friction induced magnetic induction, the wear ofFe/PTFE and Co/PTFE composites decreased gradually, which indicated that thewear resistance of composites was improved by friction induced magnetization. Butthe wear of Ni/PTFE composites increased slightly with the increase of the load,which may attribute to the changes of the wear mechanism.4. The wear mechanism was influenced by friction induced magnetization. Onthe one hand, it is good for that magnetized ferromagnetic particles will easilytransfer to and tightly adsorb on the surface of the counterpart (45steel), which canserve as “pins” to fix the transfer film firmly on the counterface, so as to promotethe formation and stability of a continuous transfer film. On the other hand, themagnetized ferromagnetic particles readily accumulate on the friction surface of thecomposite in the friction process. |
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