Research On Improvement Of The Friction And Wear Performance Of TC11 Alloy With Nanocomposite Additive

Titanium alloys are widely used in various industrial fields because of their excellent combination properties.However,the poor wear resistance of titanium alloys,resulting from the low plastic shear resistance and the weak protection of tribo-oxides,hinders their applications.Therefore,it possesses important theoretical significance and engineering application value to improve the tribological performance of titanium alloys.In this paper,the multilayer graphene/Fe2O3 composite was added to the sliding interface of TC11 alloy/GCr15 steel to improve the friction and wear performances of titanium alloys.As a comparison,the friction and wear behaviors of TC11 alloy with no and pure multilayer graphene or Fe2O3 additives were simultaneously studied.The morphology,structure and composition of worn surfaces and subsurfaces were thoroughly measured by the microscopic analysis methods of XRD,SEM and EDS.The characteristics of tribo-layers and their formation process and function were analyzed.The effect of tribo-layers on the friction and wear performances and wear mechanism was explored.The results show that the friction and wear behaviors were closely related to additive types as well as loads and additive amounts.When adding pure multilayer graphene,irrespective of the load or additive amount,the wear loss of TC11 alloy was much higher than that without additives,and the average friction coefficient was also high.For the pure additive of Fe2O3 nanoparticles,the wear loss was low but the average friction coefficient was extremely high under low loads.With an increase of load,the wear loss and average friction coefficient were relatively high,regardless of the additive amounts.For multilayer graphene/Fe2O3 composite additive,the wear loss and average friction coefficient of TC11 alloy were extremely low under the load of 20-100 N or additive amount of 0.2-0.4 g.With an increase of load to 120 N or a decrease of additive amount to 0.1 g,the wear loss and average friction coefficient rapidly increased.It was noticed that the tribo-layers with different compositions were always formed on the worn surfaces,when various nanomaterials were added.Their function would markedly affect the friction and wear performances and wear mechanism of TC11 alloy.The pure multilayer graphene additive could adsorb to the worn surface to form a tribo-layer,which possessed lubricant function because of the existence of multilayer graphene.But this tribo-layer readily lost stability and protection,due to the weak load-bearing capacity.Thus,the wear resistance of TC11 alloy was not able to be improved,and the main wear mechanism was similar to that with no additives,i.e.adhesive wear and abrasive wear.When pure Fe2O3 nanoparticles were added,the formation of tribo-layer depended on tribo-sintering.Under low loads,the wear resistance but not the antifriction performance of TC11 alloy was obviously improved,due to the relatively strong load-carrying capacity of Fe2O3-contained tribo-layer.With an increase of load,the severe wear appeared,irrespective of the additive amount.This was ascribed to the failure of unlubricated tribo-layer during sliding.For multilayer graphene/Fe2O3 composite additive,Fe2O3-predominated and multilayer graphene-predominated tribo-layers were orderly formed by sintering and adsorption.The double-layer tribo-layer possessed excellent synergistic protection effect because of good load-bearing and lubricant capacity.It would steadily exist to the end of sliding under relatively high load or low additive amount,and the mild wear occurred.As a result,an obvious and simultaneous improvement for the friction and wear performances of TC11 alloy was achieved.