| Titanium alloys have been widely applied in many different fields due to its excellent properties,but it also exists wear and adhesion phenomenon which easily leads to the structural parts failure in long term service environment and brings serious security risks and economic losses.Therefore,it is necessary to study the fretting friction properties of titanium alloys.In this paper,TC4?Ti-6Al-4V?alloy was chosen to be the test material because it was one of the earliest,the most mature process and the most widely used typical titanium alloy.Due to existing research theories in fretting wear and typical fretting friction and wear tests,the characteristics of fretting corrosion of TC4 alloy was studied in different normal loads,friction pairs and medium.The main work includes:1.The friction coefficient of TC4 alloy increases with the increase of loading;The friction coefficient of Al2O3/TC4 fluctuates more than GCr15/TC4 and Si3N4/TC4 does;The friction coefficient of GCr15/TC4 is larger than that of Si3N4/TC4 in sodium chloride solution as well as in distilled water.The numerical ordering of the friction coefficient in different medium is that the friction coefficient in dry air is larger than that in sodium chloride solution is larger than that in distilled water.2.The wear scar were analyzed by SEM and OM.The main wear mechanism of GCr15/TC4 is adhesive wear in sodium chloride solution,but Si3N4/TC4 is mainly brittle spalling.Corrosion wear appears on the surface in this two pairs;The wear mechanism of GCr15/TC4 and Si3N4/TC4 are mainly abrasive wear and fatigue spalling in distilled water;Different friction pairs and different medium corresponding to different surface morphology,this phenomenon caused by the friction pairs coordination and the composition of wear debris.The whole micrograph of TC4 alloy generally was an ellipse with a long axis of relative motion and presented the sand washed type.3.The wear performance was analyzed by three dimensional profilometer.The wear volume and wear rate were used to evaluate the wear performance.Both increased with the increasing of loads when the amplitude is fixed and the friction pairs is different.The wear rate and wear volume of Si3N4/TC4 are larger than those of GCr15/TC4,which means the abrasion resistance of GCr15/TC4 is better than that of Si3N4/TC4,and TC4 alloy performed the best anti-wear properties in sodium chloride solution;In distilled water,when the friction counterpart was Si3N4 ball,TC4 alloy performed the best anti-wear properties.4.The interaction of corrosion and wear in two different medium is quantitatively analyzed.In distilled water,the interaction ratio between corrosion and wear was negative and its proportion was very slight,distilled water only acts as lubrication and the mechanical wear caused the material losses of TC4 alloy;In sodium chloride solution,the interaction ratio between corrosion and wear was negative and its proportion was relatively small when the friction counterpart was GCr15/TC4,which means that the mechanical wear significantly accelerated the TC4 alloy material losses;When the friction counterpart was Si3N4/TC4,the interaction ratio between corrosion and wear was positive and approximately occupied 90%,which means that it significantly occupied the main function and accelerated material losses.It is indicated that the mechanical wear is the control factor for the damage of TC4 alloy,and the interaction between corrosion and wear is the main factor,and its significance will be influenced by the pH of the solution. |
PDF Full Text Request