Friction And Wear Of Floating Ring Sealing Graphite Material

The graphite material of floating ring seal is widely used because of its high mechanical strength,remarkable thermal shock resistance,wear resistance,low expansion coefficient and low friction force,and good physical properties.However,the research on friction and wear properties of floating ring sealing materials with different pairing materials is still lacking.In this paper,the ball/plane contact form was used to explore the friction and wear performance of floating ring seal graphite material.GCr15 steel ball,Si₃N₄ ceramic ball and Al₂O₃ ceramic ball were used as friction pairs,and TRB³ friction testing machine was used to conduct dry friction and corrosion-wear interaction tests respectively.The friction coefficient,wear volume and wear scar morphology were characterized.The wear mechanism of floating ring sealing graphite material under different environmental conditions was analyzed,and the wear resistance of floating ring sealing graphite material was discussed.The main research contents and conclusions of this paper are as follows:（1）In the three environmental media,the friction coefficient of the graphite material with floating ring seal appears three stages:rapid rise,fluctuation and stability.The friction coefficient in dry friction environment is always greater than that in corrosive environment.Because the solution in the corrosive environment is the effect of lubrication and friction reduction on the graphite material,its friction coefficient is small.（2）In the three environmental media,the wear volume of the graphite material increases with the increase of normal load.The wear volume in the corrosive environment is always smaller than that in dry friction environment,and the wear volume in sea water is larger than that in pure water environment,indicating that the corrosion of sea water accelerates the wear of floating ring seal graphite materials.The dual action of corrosion and wear leads to the aggravated loss of materials.（3）The surface profile curves of the three kinds of dual ball and floating ring sealing materials were compared under different normal loads.In dry friction environment,when the upper samples were GCr15 steel ball,Si₃N₄ and Al₂O₃,the surface profiles showed’U’shape,’V’shape and’W’shape,respectively.In both corrosive environments,the surface profile shows a similar’W’shape.（4）When the floating ring sealing material rubs with GCr15,Si₃N₄ and Al₂O₃,the friction dissipation energy and energy wear coefficient increase with the increase of normal load.When the hardness of the paired material is larger,the friction dissipation energy and energy wear coefficient are larger.It shows that the friction matching material has a great influence on the whole friction process,and the change of adhesion and slip conditions in the friction contact area will lead to a significant decrease in the wear resistance of the material.（5）The friction pairs of the floating ring seal material and three different materials have different wear forms under different loads.Under small loads,the main wear forms are adhesive wear and abrasive wear,while under large loads,the main wear forms are abrasive wear and oxidation wear.At the same time,there are also phenomena such as material transfer,peeling and scratching on the surface of the friction pair.（6）The electrochemical results of two corrosive solutions show that the open circuit potential in pure water is lower than that in seawater,indicating that the corrosion resistance of floating ring sealed graphite material in distilled water is higher than that in seawater.The capacitive reactance arc and polarization resistance in pure water are larger than those in seawater.The self-corrosion potential in seawater has different degrees of negative shift,and the self-corrosion current density is slightly larger,indicating that the corrosion resistance in seawater is lower than that in pure water.