Preparation Of Composite Ceramic Coatings By Plasma Electrochemical Oxidation Of TC4 Surface And Its Wear Resistance

Titanium alloys have excellent overall properties,but the low hardness and poor wear resistance of titanium alloys greatly limit their application in aerospace and medical fields.Therefore,it is meaningful to improve the surface hardness and tribological properties of the titanium alloy.In this paper,combined with hard composite ceramic coating,solid self-lubricating particle doping and laser surface texture,an antifriction and wear-resistant coating with excellent properties was prepared on the surface of titanium alloy.Firstly,the hard composite ceramic coating was prepared on the surface of titanium alloy by plasma electrolytic oxidation?PEO?technology.The influence of oxidation time on the thickness and hardness of the coating was studied,and the growth law of PEO coating was revealed.Secondly,a one-step process was used to prepare a plasma electrolytic oxidation self-lubricating composite coating.Hard Al₂O₃ particles,soft graphite particles and mixed particles were used as dopants,and PEO coating was used as the carrier skeleton to study the effect and doping mechanism of doped particles on PEO coating.Finally,laser surface texture technology was used to form textured micropores on the surface of titanium alloy to optimize the surface density of textured micropores.The storage mechanism of hard particles and soft particles by textured micropores was studied.X-ray diffraction?XRD?,field emission scanning electron microscopy?FE-SEM?,energy dispersive spectroscopy?EDS?,hardness tester,3D shaper and friction and wear tester were used to test the composition of the coating.The wear-resistant lubrication mechanism is described in terms of cross-section element distribution,wear scar,morphology,hardness,thickness and tribological properties.The results show that when the plasma electrolytic oxidation time is 15min,a composite ceramic coating with Al₂O₃ and Al₂TiO₅ as the main component,thickness of 75?m and hardness of 700HV can be prepared.After doping the appropriate particles,the coating thickness can be further increased to more than 100?m,and the hardness of the coating is 800HV.The synergistic effect of the hard Al₂O₃ particles and the soft graphite particles can not only improve the hardness and thickness of the coating,but also reduce the friction coefficient to a certain extent and greatly reduce the wear rate.When LST/PEO/self-lubricating technology is combined,it can maintain a certain degree of hardness and lubricity,and can also exert the surface texture to capture hard abrasive debris and store the lubricating particles.The surface texture of 20%areal density has the best tribological properties.