Study The Tangential Fretting Wear Behaviors Of Depleted Uranium And Ti/TiN Multilayer Film

The uranium can be applied to nuclear power plant equipment and nuclear devices due to the special material and nuclear properties.In order to satisfy the connection and structure required of engineering design,uranium will inevitably contact with other materials.When it is in transport and service period,uranium will be affect by vibration with different frequency,which could lead to the relative motion with small displacement amplitude,and the relative motion will cause fretting damage in uranium surface.Fretting damage may cause partially fatigue crack initiation and propagation,and make the service life significantly lower than that of traditional fatigue service life.Therefore,investigating the fretting wear behaviors of depleted uranium,not only provide theoretical guidance for the anti-fretting wear prosperity of depleted uranium in nuclear engineering and nuclear weapons,but also have an important role for understanding and deepening the mechanism of fretting wear.In this paper,Ti/TiN multilayer film was deposited on depleted uranium surface by cathodic arc ion plating equipment.The structure and behaviors of Ti/TiN multilayer film was investigated by scanning electron microscopy(SEM),X-ray diffraction(XRD)and Auger electron spectroscopy(AES).The ball on plant contact was used to study the fretting wear behaviors of depleted uranium and Ti/TiN multilayer film in MFT-6000 equipment.The wear scars were examined by optical microscope(OM),SEM and Energy Dispersive X-ray Detector(EDX)and white light interferometer.The wear morphology combined with the Ft-D curve systematic reveals the fretting damage mechanism and running behavior of depleted uranium and Ti/TiN multilayer film,and the main conclusions can be draw as following:(1)The Ti/TiN multilayer film is composed of many small uniform particles,and the surface is densely packed,no voids or micro-cracks.The Ti/TiN multilayer film exhibite multilayered laminate structure,and the interface of multilayer film can be clearly distinguished.The thickness of prepared film is about 2.27μm.The average Young’s modulus under 5mN force is 471.55 Gpa.(2)With the increase of displacement amplitude,the fretting regime of depleted uranium and Ti/TiN multilayer film change from the partial slip of elastic deformation coordination to the partial slip of plastic deformation,and then to slip regime.The wear profile also changes from the slight indentation to the "W" type,and then to the "U" type.The coefficient of friction(COF)can divide into three stages,namely,initial stage,rising stage and stable stage.The COF of stable stage increase with the increase of displacement amplitude.When the displacement amplitude is 50μm and 100μm,the multilayer film destroys completely,and the layered structure damage is clearly emerged from the wear scar edge.Wear volume increase with the increase of displacement amplitude.The wear volume increases remarkable,when the fretting regime change from the partial slip to the slip regime.The wear volume of Ti/TiN multilayer film is 2 orders of magnitude lower than the depleted uranium.(3)When the load is 10N,the fretting regime of the Ti/TiN multilayer film belong to slip regime,while the depleted uranium assign to mixed fretting regime,which explain that the film can change the fretting regime.The dissipation energy of multilayer film is larger than that of depleted uranium.When the load increased,the fretting regime of substrate and film belong to partial slip.When the load is 20N,the 2D profile of substrate and film are "W"type,indicated that the contact center of wear scar has a sticking zone.When the load is 100 N,the surface of substrate and film only have indentation,which mean that contact center is adhesive and micro slip occurs at contact edge with small black wear debris.Under different load conditions,the multilayer film has a lower wear area,wear depth,wear volume,and wear rate than the depleted uranium.