Effect Of ATSP Coating On Fretting Wear Properties Of CuNiAl Alloy

The adjustable pitch propeller,the core component of the dynamic positioning equipment(full-rotation thruster)of large marine installations,is under the complicated and changing marine working conditions.Due to the high frequency load of wind and waves at a fixed distance,the blade root method Planar bearings composed of blue and pulp hubs(referred to as pulp-hub bearings for short)are subject to fretting wear,which is an important reason for restricting the service life of pulp-hub bearings.Nickel-aluminum-bronze alloy is the main material of adjustable pitch propeller hub components in large high-service marine equipment due to its high strength,high hardness,wear resistance and certain corrosion resistance.Therefore,on the basis of studying the wear failure mechanism of nickel-aluminum-bronze alloy,the research on improving the fretting wear resistance of nickel-aluminum-bronze is of great practical significance for improving the service life of large high-service marine equipment.In this paper,ATSP(aromatic thermosetting co-polyester)coatings were prepared by electrostatic spray deposition on nickel aluminum bronze alloy(CuNiAl).The fretting wear characteristics and fretting wear mechanism under the condition of surface / surface contact were studied,and the friction and wear properties of ATSP coating in corrosive environment were further studied.The main research work is as follows:(1)The fretting operating characteristics of CuNiAl were studied under different load(43N,86 N,106N)and angular displacement amplitudes(0.1 °,0.5 °,1.5 °,3 °).The results show that the fretting operation state of CuNiAl alloy shows a tendency to change from a partial slip state to a complete slip state as the angular displacement amplitude increases.With the increase of load and angular displacement amplitude,CuNiAl wears more and the friction coefficient increases.CuNiAl has different wear failure mechanisms under different loads and angular displacement amplitudes(i.e.different fretting operation state): partial slip state: plastic deformation and fatigue crack;mixed slip state: abrasive wear,plastic deformation,oxidation and delamination;complete slip state: delamination and abrasive wear.(2)The fretting wear performance of the ATSP coating under different loads and different lubrication conditions was studied.The wear resistance performance was compared with and without the coating,and the friction and wear reduction of the ASTP coating was revealed(loss)mechanism.The results show that under the same conditions,the friction torque and wear of the ATSP coating are lower than that of CuNiAl(uncoated);the maximum wear scar depth of the ATSP coating is less than 6um,which is 90% less than that of CuNiAl(uncoated).The analysis shows that the complex friction chemical reaction occurs during the wear process of the ATSP coating,and the generated abrasive debris will gradually accumulate to form a transfer film,which plays an important role in reducing the friction torque and wear depth of the ATSP coating.(3)The fretting friction and wear characteristics of ATSP coating in different water media(water,sea water,deionized water)were studied.The results show that ATSP coating has super low water absorption and is difficult to plasticize.The results of friction and wear test show that ATSP coating has the most stable friction torque in seawater environment,the lowest friction moment in water environment and the lowest wear amount in deionized water.The different friction and wear characteristics of ATSP coating in different water medium are caused by the corrosion of ATSP coating on 42 Cr Mo,i.e.indirect corrosion,which affects the surface morphology of contact interface.