Study On Frictional Wear Behavior Of Surface-reinforced TC4 Alloy In Different Friction Systems

Titanium alloy has outstanding comprehensive mechanical properties such as high specific strength,low density and good metal properties,and is widely used in the manufacture of key parts such as aero-engine turbine blades,medical equipment and human implanted joints and steam turbine blades.When titanium is used as a friction pair material,poor tribological characteristics can easily lead to wear,causing solid particle pollution,corrosion,fatigue and other problems.Titanium alloys are not easy to overcome adhesion effects and are easy to "stick weld" with paired friction pairs,so wear resistance has become a key consideration for the use of titanium alloys to manufacture structural parts.In order to overcome the poor wear resistance of TC4 alloy,the surface of TC4 alloy was strengthened by micro-arc oxidation process to form a hard ceramic film(MAO-TC4 alloy)and the surface of TC4 alloy was strengthened by laser impact strengthening process to form a nanocrystalline layer(LSP-TC4 alloy).Nanocrystalline layer(LSP-TC4 alloy),to study the frictional wear performance and failure analysis of surface-reinforced TC4 alloy in different normal loads and different friction systems(TC4 alloy balls,GCr15 steel balls and Si3N4 ceramic balls)at room temperature environment.The main research results are as follows:1.The friction coefficient curves of TC4 alloy and reinforced TC4 alloy surface in different friction systems can be divided into three stages:rising,falling and fluctuating,the friction coefficient increases with the increase of normal load,the degree of fluctuation of the friction coefficient curve increases gradually with the increase of normal load and the hardness of the counterbalance ball,and the "sawtooth" fluctuation state was broken.Compared with TC4,the surface friction coefficient of micro-arc oxidation and laser impact strengthened TC4 alloy is smaller.2.In the frictional wear process of TC4 alloy and LSP-TC4 alloy with the three pairs of frictional subsets,the strengthening process does not affect the composition of the metal itself,and the frictional wear volume of the frictional subsets of the two target study metals paired with the three pairs of balls increases with the increase of the normal load and the hardness of the pair of balls,and the oxidation of the contact area gradually increases with the increase of the hardness of the pair of balls.In the frictional wear process between MAO-TC4 alloy and the three counterbalance balls,the ceramic film can effectively prevent metal oxidation and form the smallest wear volume with TC4 alloy ball,the largest wear volume with GCr15 steel ball,and the wear volume with Si3N4 ceramic ball is in between.3.The frictional dissipation energy of TC4 alloy,MAO-TC4 alloy and LSP-TC4 alloy in different friction systems shows a rising trend with the increase of normal load and hardness,the wear volume and frictional dissipation energy are positively correlated,the frictional dissipation energy is released by frictional heat,oxidation and plastic deformation during the frictional wear process,forming different frictional wear morphology and wear mechanism;from the energy dissipation and The law of friction wear process is revealed by energy dissipation and transformation.4.The wear mechanism of TC4 alloy ball pairing is adhesive wear and abrasive wear,in which the adhesive wear gradually increases and the abrasive wear gradually decreases with the increase of load.The wear mechanism of the Si3N4 ceramic ball pairing is abrasive wear and oxidation wear,with abrasive wear distributed at the contact edge and slight oxidation wear and fatigue wear at the contact center.5.TC4 alloy and two kinds of reinforced TC4 alloy and three kinds of contact body friction scratch morphology,and TC4 alloy ball friction,micro-plane/plane contact state so that the abrasive particles in the scratch ends of the accumulation of serious,"pad" contact area,the indenter in the"climbing When the contact state of micro-plane/plane makes the abrasive particles accumulate at both ends of the scratch,"padding" the contact area,and the indenter is in "climbing" motion.Friction with GCr15 steel ball and Si3N4 ceramic ball,the hardness of the upper contact body in the process of slippage in the front of the indenter to form a dislocation wall,the rear end of the indenter has adhesion fracture to form a spalling pit,so that the depth of the scratch appears to fluctuate periodically,the profile is "U"-shaped.6.The metal friction process by the interaction of micro plowing and micro cutting two deformation mechanisms,any one pair of friction on the top and bottom of the specimen scratch width and scratch length with the change in load is a linear trend,TC4 alloy friction scratch cutting and plasticity ratio fcp=0.9～1 between the most serious micro cutting mechanism,resulting in the maximum scratch length and width,the formation of the scratch hardness is smaller;LSP-TC4 alloy and MAO-TC4 alloy form scratches with cutting to plasticity ratio fcp distribution fcp=0.8 on both sides,with slight micro-cutting mechanism and serious micro-plowing mechanism,resulting in the smallest scratch length and width and larger scratch hardness.