Surface Friction And Wear Properties And Lubrication Mechanism Of Textured HA/ZrO₂ Coatings

Wear is one of the main reasons affecting the service life of artificial joints.In addition to the characteristics of the materia,the lubricating properties of the lubricant also play an extremely important role.Due to its good biocompatibility and bioactivity,hydroxyapatite?HA?has similar properties in composite bioceramic coatings,and thus has broad application prospects in the field of artificial joints.However,the coating itself has obvious defects,such as poor wear resistance and high brittleness.Therefore,the HA/ZrO2 composite coating is mixed with ZrO₂ powder to improve the tribological properties of the HA coating material to prolong the service life of the artificial joint.Surface texture is a process technology that improves surface properties.It can be effectively applied to the surface of materials to improve surface properties.This has been widely proven in many fields,so it is widely used in engineering fields such as bearings and mechanical seals.Lubrication performance is closely related to its own wetting performance.The better the wetting property,the better the lubrication performance,and the contact angle of the material surface directly reflects the wetting property of the material.Therefore,the contact angle can also indirectly reflect the lubrication performance.Hyaluronic acid is one of the main components of human synovial fluid.The main components of bovine serum are close to various proteins in human blood.Therefore,sodium hyaluronate and bovine serum are used as lubricants based on infiltration model.The edge triangles have different parameters of diameter to diameter and depth.It is verified by contact angle test whether the influence of two factors on the contact angle is consistent with the theory,and the advantages and disadvantages of the two lubricants are compared.In addition,in order to explore the application effect of texture in the field of bioceramic materials,this paper establishes the theoretical model of the textured surface in the mixed lubrication state based on deterministic model.Through the Matlab software,the equation is discretized by the finite difference method and combined with the numerical value.Iteratively solves the mixed lubrication model,and obtains the pressure distribution in the calculation domain and the theoretical friction coefficient of the textured surface,and uses this as the criterion for judging the friction and wear properties of the textured surface,and guides the subsequent friction and wear test.On the basis of this,this paper uses the femtosecond laser processing technology to process the equilateral triangle texture array with different texture-to-diameter ratio and different depth on the surface of zirconia-reinforced HA bioceramic coating.The friction and wear test is based on the reciprocating test platform,and the three-dimensional contour instrument is utilized.The wear depth of the coating is investigated,and the texture design parameters of the coating with better wear resistance are investigated.The main conclusions of this paper are as follows:?1?The wettability of sodium hyaluronate on the surface of HA/ZrO₂ composite ceramic coating is better than that of bovine serum solution,and the contact angle of both solutions gradually decreases with the increase of texture depth.?2?Under the condition of mixed lubrication,the theoretical friction coefficient increases first and then decreases with the depth of texture,and both change at a depth of 70?m.With the increase of the inter-textile ratio,the friction coefficient increases gradually.However,in all the texture samples,the sample group with a texture-to-diameter ratio of 3 achieved a small friction coefficient at each depth,and the test with a depth of 90?m achieved a minimum value of 0.071,which is the most contact angle.The parameters of the surface of the good texture are the same,and the rationality of the statement that the contact angle is smaller and the lubricity is better is verified.?3?The friction and wear properties of equilateral triangle textures with different distance-to-diameter ratios and different depths were studied by reciprocating friction and wear tests under the condition of 0.5%sodium hyaluronate lubrication.The results show that the inter-textile ratio is 3 and 5,and the friction coefficient with the depth of 90?m is the lowest,0.203and 0.194,respectively,but the sample with a ratio of 5 is the smallest.In addition,the friction coefficient of different depth texture samples is similar to the simulation results,and generally shows a trend of rising first and then decreasing,but in contrast,the friction coefficient obtained by the test is much larger than the simulation result,given the complex and variable working conditions.In this paper,the texture surface of certain parameters is designed by the contact angle theory.The wetting properties of the two lubricating fluids are compared by the contact angle test.The friction and wear tests are carried out with better lubricants.The different texture parameters are applied to the coating surface.The influence of friction coefficient provides a reference for the selection of artificial joint lubricants and the application of surface texture technology in the field of bioceramic coatings.