Study On Tribological Properties Of Black Phosphorus/Polytetrafluoroethylene Self-lubricating Materials For Ships

In this paper,sliding bearings of ship are taken as the research background,polytetrafluoroethylene（PTFE）was used as the matrix material,and two-dimensional black phosphorus（BP）nanoflakes was added to it to improve its tribological performance.At the same time,due to the characteristics of BP nanolfakes that it is easy to be oxidized and can not exist stably in the air,the degenerated black phosphorus（d-BP）/PTFE composites were further prepared,then the tribological properties of the composites were evaluated and compared with other composites.In this paper,BP nanoflakes was prepared by high-energy ball milling method and characterized by a variety of analytical and testing methods.The purity of the final prepared BP nanoflakes was about 93.51%,presenting a layered stacked structure.The BP nanoflakes was mixed with PTFE by mechanical mixing,then BP/PTFE composites were prepared by high temperature plasma discharge sintering method,and a series of characterization methods were used to characterize the prepared composites.The main work of this study are as follows:（1）C/PTFE,Mo S₂/PTFE and PI/PTFE composites were prepared by high temperature plasma discharge sintering as the compare group,and dry friction experiments were carried out under the same experimental conditions to evaluate the tribological properties of the composites.The experimental results showed that due to the degradation of BP nanoflakes during the friction process,the formation of phosphorus oxides adhering to the friction area made the BP/PTFE composites have the best tribological properties.Compared with pure PTFE,the COF of BP/PTFE composites was reduced by 25%and the wear rate was reduced by 63%.（2）Hydrogen peroxide was used as oxidant,the prepared BP flakes was locally oxidized and mixed with PTFE powder,and the locally oxidized BP nanoflakes/PTFE composite was prepared by high temperature plasma discharge sintering method.Dry friction experiments were carried out on locally oxidized BP nanoflakes/PTFE composites under the same conditions.It was found that the presence of appropriate locally oxidized black phosphorus nanosheets could effectively reduce the COF（below 0.08）and wear rate of the composites,and the comprehensive tribological properties of the composites were better than those of the unoxidized BP nanoflakes/PTFE composites.（3）The tribological properties of the prepared fresh BP nanoflakes/PTFE and the locally oxidized BP nanoflakes/PTFE composites were compared under water lubrication condition.Because locally oxidized BP nanoflakes can form a stable water layer in the friction contact area,the COF of locally oxidized BP nanoflakes/PTFE composites in water environment can be kept at about 0.267 for a long time,while the wear rate can be significantly reduced to7.88×10^-5mm³·N^-1·m^-1,exhibiting an excellent tribological property in water environment.