Friction Mechanism Of Functionalized Ti₃C₂T_x Modified Interpenetrating Polymer Network Under Multi-Working Conditions

Interpenetrating polymer network(IPN)possesses the characteristics of good thermal stability,excellent mechanical properties and weather resistance.IPN served as a polymer coating can protect the metal substrates from the external damage and prolong its service life.However,various defects were inevitably generated during the curing process of IPN.The formation of defects can lead to poor compactness,which seriously affected the tribological properties of the polymer coating.It is difficult for a single coating to meet the continuous requirements of excellent tribological properties under multi-working conditions(ultraviolet irradiation,corrosive media).Therefore,in this thesis,the tribological properties of IPN coating under multi-working conditions were enhanced by introducing the modified Ti3C2Tx.In this thesis,a poly acry late/epoxy interpenetrating polymer network was synthesized by emulsion polymerization and used as the matrix of the polymer coating.In order to enhance the tribological properties of IPN coating under multi-working conditions,aminated-Ti3C2Tx nanosheets were introduced into IPN as the reinforcing phase to improve the dispersibility and compatibility in IPN coating.The ZnO nanosheets with excellent ultraviolet(UV)absorption and wear resistance were loaded on the surface of Ti3C2Tx nanosheets by a one-step hydrothermal process.The as-prepared Ti3C2@ZnO heterojunction composites were introduced into IPN coating to further improve the tribological properties and prolong its service life under multi-working conditions.Compared with the pure IPN coating,the composite coating exhibited more excellent tribological properties under multi-working conditions.The main conclusions are as follows:(1)Preparation and properties of aminated-Ti3C2Tx modified IPN composite coatingThe amino-functionalized Ti3C2Tx(k-Ti3C2)nanosheets were introduced into the IPN coating,and it was found that the composite coating with 0.75 wt%k-Ti3C2 nanosheets(kTi3C2-0.75)exhibited the best tribological properties in multi-working conditions(UV radiation,corrosive media).The adhesion strength values of k-Ti3C2-0.75 composite coating before and after UV aging were increased by 53.2%and 85.7%,respectively.Further,the wear rates of the k-Ti3C2-0.75 composite coating before and after UV aging were reduced by 82.4%and 74.6%under dry friction compared with the pure IPN coating,respectively.And the wear rates in the tribocorrosion test were reduced by 50.5%and 82.7%,respectively.The salt spray test found that the oxygen content in the corrosion products under the k-Ti3C2-0.75 coating before and after UV aging was 30.0%and 22.5%lower than that of the pure IPN coating,respectively.Therefore,the k-Ti3C2-0.75 composite coating had better corrosion resistance.The dispersibility and compatibility of fillers in composite coating were improved due to the enhanced interface interaction between k-Ti3C2 nanosheets and IPN molecular chains.Meanwhile,k-Ti3C2 nanosheets as barriers played a key role in the composite coating,reducing the propagation channels of corrosive media,thereby improving the corrosion resistance of the composite coating.(2)Preparation and properties of ZnO modified Ti3C2Tx Enhanced IPN coatingTi3C2@ZnO/IPN composite coating was prepared by adding the well-dispersed Ti3C2@ZnO heterojunction composites as reinforcing phase to IPN for improving the tribological properties under UV irradiation and corrosion conditions.After UV irradiation,the wear rates of Ti3C2@ZnO/IPN composite coating were reduced by 81.85%and 80.4%compared with pure IPN coating under dry friction and tribocorrosion,respectively.Meanwhile,the storage modulus and adhesion strength were increased by 74.4%and 502.5%,respectively.The composite coating still demonstrated excellent tribological properties under multi-working conditions.This can be attributed to the following aspects.Firstly,a part of UV light was reflected and absorbed by Ti3C2@ZnO,which weakened the photo-oxidative degradation reaction of the composite coating.Secondly,the Ti3C2@ZnO heterojunction composite material can fill in the wear track during the friction test and form the tribo-film,which isolated the direct contact between the coating and the friction pair and reduced the friction and wear.Simultaneously,Ti3C2@ZnO had a good barrier effect in corrosive environment,which improved the corrosion resistance of the composite coating.