Study On Stiffness Calculation And Dynamic Characteristics Of Modified Spur Gear

Titanium alloys are widely used in aerospace,biomedical and marine applications due to their low density,high specific strength and excellent resistance to corrosion^[1].However,their weak frictional wear properties limit their engineering applications.Compared to hard films such as Ti N and Ti Al Cr N,diamond-like containing hydrogen（DLC）films have high hardness and low friction properties,making them one of the most promising lubricating materials for reducing friction and wear of frictional substrates.a-C:H films have been extensively studied on the surfaces of steel and silicon substrates,due to the high surface activity of titanium alloys and the high internal stress of a-C:H films resulting in weak film-based bonding.a-C:H films are highly resistant to the environment.:H films are highly sensitive to the environment and are difficult to achieve superlubricity due to factors such as water molecules and oxygen in the air.To address the environmental sensitivity of a-C:H films and the achievement of superlubrication on titanium alloy surfaces.This paper investigates the superlubricity performance and mechanism of a-C:H films and molybdenum disulphide（MoS₂）by constructing a composite film with a heterogeneous structure of a-C:H films,and the research in this thesis includes the following three main aspects.（1）Ti/Ti C/a-C:H thin films were prepared on the surface of titanium alloys using magnetron sputtering（Magnetron sputtering）and characterised by Raman spectroscopy,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,atomic force microscopy（AFM）,nanoindentation and three-dimensional profiling to characterise the wear spots and abrasion marks as well as the mechanical properties and structure of the films.The frictional wear properties and mechanism of a-C:H films under different loads and inert gas environments were investigated.The results showed that the a-C:H films on titanium alloy surfaces under inert gas and atmospheric environments were difficult to achieve superlubricity with a coefficient of friction of 0.025.The frictional stress induced led to a phase change in the a-C:H films.（2）MoS₂/a-C:H composite films were constructed on the surface of titanium alloy using drop coating method,and the composite films were characterized compositionally using SEM,Raman and TEM for microstructure and friction products（wear marks,wear spots and wear chips）.The effects of different loads on the friction and wear properties of the composite films were investigated under helium（He）environment.The results show that at the contact interface,the composite film achieves superlubricity with a friction coefficient of 0.007 due to the formation of non-public contact.a-C:H film and MoS₂’s own structural transformation,the formation of graphene and MoS₂ nanoscroll structures successfully achieve structural superlubricity.（3）The results of this study show that humidity and counter material are important factors affecting superslip,and when Al₂O₃ and Si C are used as counter materials,it is easier to produce superlubricity with coefficients of 0.008 and 0.007 respectively.Superlubricity is achieved due to the synergistic effect of graphene and MoS₂.