Erosion Wear Performance Of PVD Nitride And Diamond-like Carbon Hard Coatings

PVD coatings are widely used in the field of friction and wear due to their high hardness,good wear resistance,low friction coefficient and chemical stability.In the harsh erosion environment,the parts and components coated PVD hard coatings could be more effective to resist solid particle erosion,which makes their life service be longer.In the investigation,AlCrN and TiAlSiCN coatings were deposited onto three substrates of titanium alloy TC4,cemented carbide YG6 and YT15 by cathodic arc ion plating.And Diamond-like carbon DLC coatings were deposited onto the same three substrates by magnetron sputtering.Erosion wear performance of these coatings was studied systematically.The microstructure,phase composition and main physical and mechanical properties of the coatings were tested and analyzed.The results are summarized as follows:(1)Elements in the coatings are well distributed.Fine dense and uniform thickness of the coatings could be observed.The bonding between the coating and the substrate is excellent It is discovered that the element diffusion occurs in the interface between substrate and coating.(2)It is shown that AlCrN coating consisted of AlN phase and CrN phase and TiAlSiCN coating consisted TiN phase.Raman Spectra of DLC coating have been evaluated by Gaussian fitting,which showed that a G peak appeared near 1568 cm-1 and a D peak appeared near 1397 cm-1.(3)It is found that hardness values of the same coating on different substrates are little difference.Among the three coatings,the TiAlSiCN coating has the highest hardness of about 32 GPa,and the AlCrN coating has the lowest hardness of about 23 GPa.The elastic modulus and plastic deformation index Rp of the coating on the TC4 substrate are smaller than those of other substrates.It is analyzed that the DLC coating has the lowest bonding strength with the substrates among the three coatings.Compared with YG6 and YT15 substrates,TC4 substrate has a lower bonding strength with each coating.The erosion wear characteristics of the coatings on the three substrates were studied by sandblasting erosion test.The results are summarized as follows:(1)The erosion resistance of different coatings on the same substrate was different.The ranking of the erosion rate of the coatings coated onto the TC4 substrate was AlCrN<TiAlSiCN<DLC<TC4,and the erosion rate of AlCrN coating was just 1/10 times of that of the TC4 substrate.The ranking of the erosion rate of the coatings coated onto the YG6 substrate was TiAlSiCN<AlCrN<DLC<YG6,and the erosion rate of TiAlSiCN coating was just 1/11 times of that of the YG6 substrate.The ranking of the erosion rate of the coatings coated onto the YT15 substrate was TiAlSiCN<AlCrN<DLC<YT15,and the erosion rate of TiAlSiCN coating was just 1/11 times of that of the YT15 substrate.(2)The erosion resistance of the same coating on the different substrate was different.The erosion rate of AlCrN coating coated onto the TC4 substrate is the lowest,while coated onto the YT15 substrate is the highest.The erosion rate of TiAlSiCN coating coated onto the YT15 substrate is the lowest,while coated onto the TC4 substrate is the highest.The erosion rate of DLC coating coated onto the YT15 substrate is the lowest,while coated onto the TC4 substrate is the highest.(3)By analyzing the factors which could affect the coating's erosion performance,it is founded that the erosion resistance of the coating was not only related to its mechanical properties,but also to the substrate which it deposited onto.Under high impingement of solid particle erosion,the coating with high hardness,proper plastic deformation ability,good bonding strength with the substrate had better erosion resistance.By analyzing the micro morphologies of the erosion surfaces of the coatings,the erosion wear behavior of the coatings was discussed.The results are summarized as follows:(1)The erosion wear behavior of the AlCrN coating on the early stage mainly included micro-cutting marks and plastic extrusion deformation of large particles.As the erosion progresses,the coating exhibited brittle fatigue fracture.(2)The erosion wear behavior of the TiAlSiCN coating was caused by the occurrence of cracks around the surface of the cavity and the position where the large particles were peeled off by solid particles.And the crack propagation leaded to brittle fracture of the coating material.(3)The main erosion wear behavior of the DLC coating on the TC4 substrate was dee to the crack initiation,propagation and intersection,which leaded to brittle fatigue fracture of the coating material.The DLC coating on the YG6 and YT15 substrates was removed in the way of micro-cutting and brittle fatigue fracture.