Study On Preparation,microstructure And Tribological Properties Of TiVCrZrW(N) Coatings

In recent years,a new material:high entropy alloy,has attracted extensive attention because of its high hardness,high strength,corrosion resistance,friction resistance and oxidation resistance.High entropy alloy coating prepared by surface coating technology is regarded as a more advanced material.The appearance of high entropy alloy coating provides a new idea for improving the surface protection performance of ships and aircraft.In this paper,the commonly used substrate materials in the industry are selected:titanium alloy,aluminum alloy,stainless steel,single crystal silicon,and the Ti-V-Cr-Zr-W splicing target is designed independently.TiVCrZrW coatings were prepared by reactive DC magnetron sputtering technology,and the process parameters were optimized.Firstly,the TiVCrZrW coating was annealed at different temperatures by using the TCHEA4 database simulation calculation of Thermo-Calc ^TM.The phase transformation process of the TiVCrZrW coating at different annealing temperatures was analyzed,and the microstructure of the coating after annealing was characterized.Afterwards,the tribological properties of the annealed TiVCrZrW coatings were tested under the conditions of coating-base oil-air three-phase contact and base oil full coverage.In addition,N element was introduced into the TiVCrZrW coating to obtain a high-entropy ceramic coating with better comprehensive properties,and its surface structure,mechanical properties,corrosion resistance and friction resistance were systematically studied.The specific research contents and results are as follows:The TiVCrZrW coating was prepared using the self-designed Ti-V-Cr-Zr-W spliced target,the Ar flow was regulated to 100 sccm,the sputtering power was 200 W,and no bias voltage and substrate temperature were applied.Friction and wear tests under different contact environments were carried out on TiVCrZrW coatings annealed at different temperatures(450??900?).When the annealing temperature reaches 900?,its tribological properties are the best.The analysis results show that the bimetallic oxide Zr Ti O₄,a friction reaction product generated in the three-phase contact environment,significantly reduces the friction coefficient of the coating.The TiVCrZrWN_x high-entropy ceramic coatings were prepared by using the same deposition conditions as those of TiVCrZrW coatings and introducing different N₂flow rates.Under the nanoindentation test,when the N₂flow was 24 sccm,the hardness of the TiVCrZrWN_xcoating reached the best(21.27 GPa),which was nearly 24%higher than that of the pure TiVCrZrW coating(17.13 GPa).In the electrochemical experiments using simulated seawater(3.5 wt%Na Cl solution)as the corrosion medium,when the N₂flow rate reached a saturated 24 sccm,the self-corrosion current of the TiVCrZrWN_xcoating was the lowest;the tribological properties of the coating in the simulated seawater environment were characterized.The results show that it is the formation of V₂O₅lubrication phase that makes the coating with N₂flow rate of 24 sccm obtain the best tribological properties.