Preparation Of Ti-Al-C-N Coatings With High Hardness And Outstanding Wear Resistance

The wide range of chemical and phase compositions provide the quaternary Ti-Al-C-N hard coatings with outstanding mechanical and triological performances.However,due to the limited available data of the quaternary phase diagram,the relationship between the chemical composition and phase structure of the Ti-Al-C-N coating is still unclarified and thus requires further study.Magnetron sputtering technology is an ideal choice for fabricating dense hardcoatings.Consequently,this work focuses on develop new Ti-Al-C-N hard coatings with good mechanical and triological performances by using radio frequency magnetron sputtering and hot filament plasma enhanced magnetron sputtering new technology.The influence of chemical compositions and deposition parameters on the phase structures,morphologies,mechanical and triological performances of the as-deposited Ti-Al-C-N coatings were investigated.And the Ti-Al-C-N coating with optimized compositions exhibits low wear rate and ultrahigh hardness of 4636 HV_10g,the highest value ever reported in Ti-Al-C-N.The research includes:1)A series of Ti-Al-C-N coatings were prepared by radio frequency magnetron sputtering technology,and Ti-Al-C-N coatings with different C and N contents were obtained by tuning the angle of the C target and the N₂flow.The results show that with the increase of the C content,the phase structure in coatings changes from single fcc-TiN phase to fcc-TiN+?-C.The preferred growth direction of TiN phase changes from(111)to(220).The increase in C content results in complex changes in lattice paraters i.e.,it first increases and then decreases with the increase of C content.In contrast,the grain size of TiN is almost the same.When the N content increases,the phase structure of the coatings with low-C content changes from fcc-Ti C phase to fcc-TiN and that of the coatings with high-C content changes from fcc-Ti C+?-C to fcc-TiN+?-C phase.When the C content is 26 at.%and the N content is 26 at.%,the hardness of the Ti-Al-C-N coating reaches the highest value of 4310 HV_10g.However,due to the brittleness,the wear rate is high(4.1×10^-5?m³/mm N).2)The Ti-Al-C-N coatings were prepared by hot filament plasma enhanced process and the influence of the deposition parameters on the Ti-Al-C-N coating was studied.The results show that the increase of the discharge current resuts in dramatical improvement in hardness.With the increase of the substrate bias,the preferred orientation of the TiN crystal changes,and the hardness of the coatings increases.The extension of the deposition time increases the thickness,the hardness of the Ti-Al-C-N coatings increases.3)Based on the optimized deposition parameters,series of Ti-Al-C-N coatings with different C and N contents were formed by hot filament plasma enhanced radio frequency magnetron sputtering.The results show with the increase of the C content,the phase structure in coatings changes from single fcc-TiN phase to fcc-TiN+?-C.The preferred growth direction of TiN phase changes from(111)to(220).The increase in C content results in complex changes in both lattice parater and grain size of TiN i.e.,the lattice parater first increases and then decreases with the increase of C content.In contrast,the grain size of TiN increases continueously.When the N content increases,the phase structure of the coatings with low-C content changes from fcc-Ti C phase to fcc-TiN and that of the coatings with high-C content changes from fcc-Ti C+?-C to fcc-TiN+?-C phase.When the C content is 17 at.%and the N content is 28 at.%,the Ti-Al-C-N coatings display both ultrahigh hardness of 4636 HV_10g and low wear rate of0.6×10^-5?m³/mm N.