Study On Tribo-corrosion Behavior And Mechanisms For PVD Coatings Prepared By Magnetron Sputtering

Compared with the terrestrial environment,the marine environment is very harsh with strong corrosive.Marine engineering equipment,such as marine transportation ships,seabed gas/oil mining equipment and underwater robots,is working in a harsh environment for a long time,facing the problems of corrosion damage,abrasion failure and biological fouling,which seriously affect the work efficiency,stability and service life of marine engineering equipment,which also restricts the development of major marine engineering technology and equipment.Therefore,the protection technology applied to marine environment has become one of the key problems to be solved in the field of marine engineering.Physical vapor deposition?PVD?hard coating is a kind of common wear resistant protective coating.It has been widely used in the actual surface protection,which can reduce the wear of moving parts in quantity and improve the service life of the engineering equipment.However,there are many defects in the PVD coating?vacancy,grain boundary,pore and so on?,which may become the first failure point during the corrosion process,and cracks originated in the process of mechanical action form the rapid diffusion channel of the corrosion liquid and aggravate the coating loss.The properties of coating's crack resistance can be reduced by the brittle enhancement or the chemical reaction in the water environment.Therefore,common PVD protective coating cannot be simply transplanted to mechanical corrosion coupled ocean conditions.Studying the abrasion behavior of PVD hard coatings in marine environment is of great significance for marine protection technology.In this paper,the reactive magnetic sputtering method was used to prepare the CrSiN coating with controllable composition and growth structure by adjusting the target pressure and the substrate bias voltage.The abrasion behavior of PVD hard coating was systematically studied and its failure mechanism was explored.The main conclusions are as follows:?i?On the basis of composition,Cr_0.58Si_0.42N showed better corrosion resistance and best wear resistance,but it did not show the best wear resistance.The wear and corrosion resistance of coatings should not only consider the corrosion and wear properties of coatings,but also the brittleness and chemical reaction of coatings in water environment.?ii?On the basis of growth structure,a dense columnar coating exhibited a lowest tribo-corrosion rate of 6×10^-16 m³/N m,which proceed mainly by the removal of passive layer in the layer-by-layer mechanism.A columnar and porous coating failed for its poor intrinsic corrosion resistance,whereas an almost column-free coating failed for its fracture-dominated wear.It could be found that high compactness,effectively crack-controlled wear,and dynamic equilibrium of depassivation-repassivation on worn surface would be indispensable for the tribo-corrosion resistant hard coatings.