Design And Optimization Of The Transition Layer Based On The Adhesion Of DLC/AISI 316L

In order to improve the adhesive strength between Diamond-like carbon film(DLC)and austenitic stainless steel AISI 316L,three composited films with different transition layers,such as nitrided layer,pure Crlayer and CrN_X layer,were synthesized on the surface of AISI 316L using a combination method of plasma enhanced magnetron sputtering(PEMS)and plasma enhanced chemical vapor deposition(PECVD),respectively.The phase stricture,morphology,adhesive strength and tribological properties of the composited DLC films were characterized by XRD,Raman spectroscopy,SEM,3D optical microscope,scratch tester,nano-indention tester,and friction and wear tester.First,the effect of the nitrided layer on the phase structure,adhesive force and tribological properties of DLC films deposited at different temperatures was studied.The results show that during the deposition of DLC film,nitrogen atoms continued to diffuse into the substrate,increasing the thickness of the nitrided layer by 4-7?m;at the same time,nitrogen atoms out-diffused to form precipitated phase at a higher deposition temperature(150°C).At lower temperatures(?100°C),the precipitation-free nitrided layer improved the adhesive force between the DLC film and substrate by176%.The nitrided layer can also promote the formation of sp³ bonds in the DLC film,increasing the hardness of DLC film by 9%-23%and reducing the friction coefficient from 0.2 to 0.1.Secondly,the phase composition and tribological properties of DLC film combined with pure Crlayers with different duty cycles were investigated.The results show that the growth orientation of pure Crlayer changed from(110)to(200)as the duty cycle increased.After deposition of the DLC film,the preferred orientation of all pure Crtransition layers was(200).The nano-hardness and Young's modulus of Cr/DLC composited film were higher than that of single DLC,and the adhesive force was slightly higher than that of single DLC.The single DLC film cracked during the wear test,and its wear rate was up to 1618.8×10^-16 m³/(N·m).The wear rate of the composited DLC films was significantly reduced.In case of Crlayers with 60%and80%duty cycle,the wear rate of the composited DLC films was reduced to below4×10^{-1 6} m³/(N·m),and the wear resistance was significantly improved.Finally,the phase structure,adhesive force and tribological properties of DLC film combined with CrN_X layers deposited at different nitrogen flow rates were studied.The results show that with the increase of the nitrogen flow rate,the phase of the CrN_Xlayers changeed from Crto CrN through Cr₂N,and the thickness of CrN_X layers increased first and then decreased.Before depositing the DLC film,Ar⁺ions sputtering clean played a thinning effect on the CrN_X films.Among them,CrN₃₀ layer showed the most obvious thinning effect,of which the thickness was reduced from 4.1?m to 3.6?m.After the deposition of DLC film,the half-width of each phase in the CrN_Xlayer decreased,indicating an increase in the crystallinity.When the CrN_X transition layer was mainly composed of Cr₂N phase,the adhesive force between the DLC film and the substrate can be significantly improved,and the wear rate was reduced.CrN₃₀/DLC composited film had the highest adhesive force,which was 65%higher than that of a single DLC film,while CrN₄₀/DLC composited film showed the best wear resistance with a wear rate of only 1.47×10^-17 m³/(N·m).