Study Of SMA/polymer Interfacial Adhesion Properties And Interfacial Friction Performance Of Metallic Materials

Interface refers to the region between different phase materials.According to the different forms of motion at the interface,the interface can be divided into two types.The first type of interface is defined as the bonding interface,where there is no relative displacement between different phases at the interface.The first type of interface is usually found in composite materials.The first type interface is usually supposed to have better bonding performance to avoid the interface failure,which means the composite material can have better overall performance.The second type interface is the friction interface between the relative motion two phases.For the friction interface,it is usually hoped that it has a lower friction coefficient and wear rate,thus enhancing the service life of materials.The performance of these two kinds of interfaces is systematically studied in this thesis.Firstly,aiming at the first kind of interface problem,the interface performance of shape memory alloy composite is studied.Shape memory alloy(SMA)refers to metal materials with shape memory effect,which can recover the deformation under specific conditions.The Ni-Ti shape memory alloy that used in this thesis has the characteristics of super elasticity,pseudo elasticity and high damping as well.As a material with excellent performance,Ni-Ti shape memory alloy is combined with other materials to fabricate composite materials.However,it is found that the weak interface performance between Ni-Ti shape memory alloy and polymer matrix will reduce the properties of composites.In order to solve this problem,a new method of modifying the Ni-Ti shape memory alloy with silane coupling agent KH550 and Al2O3 nanoparticles was proposed.The interfacial bonding properties of SMA/polymer matrix was studied with single fiber pullout experiment.Secondly,the SMA/glass fiber/resin hybrid composite laminates and the SMA/basalt fiber /resin hybrid composite laminates were fabricated in this thesis.The interface between SMA and polymer matrix was modified to study the effect of the interfacial properties of SMA/resin on the overall properties of the composites.The relative position relationship between SMA/glass fiber/resin matrix was observed by scanning electron microscope(SEM).The mechanical properties of SMA/glass fiber/resin hybrid composites and SMA/basalt fiber/resin hybrid composites were investigated by quasi static uniaxial tensile,three point bending and low velocity impact test.The morphology of the damaged specimens was observed by SEM.Then,to the second type interface problem,the effect of the changed mechanical properties of the tribologically transformed structure(TTS)layer on the wear properties of the friction interface of metal materials is studied in this thesis.In the process of metal friction and wear,the morphology and properties of the friction interface will be obviously changed,which will affect the wear behavior.In this paper,aluminua balls are used to perform the ball-on-plane fretting tests on 316 stainless steel,pure copper and Ti6Al4 V three metal materials.Nano indentation method was used to measure the TTS layer hardness after fretting.After that,the Focused Ion Beam(FIB)was used to cut and polishing the cross-section of wear scars then observed with SEM.After that,classical Archard wear model was improved with the changing performance of TTS layer to obtain better wear volume prediction.Due to the poor wear performance of the light alloy surface,a new Plasma Electrolytic Oxidation(PEO)/Chameleon composite coating was coated on the surface of the aluminum alloy in this thesis.The tribological properties in different environments were studied.The surface of the PEO/Chameleon coating was cut by FIB.The microstructure and cross section morphology of the coating were studied by SEM.The distribution of elements on the cross section of the coating was studied by using the Energy Dispersive Spectroscopy(EDS).In addition,the friction and wear properties of PEO/Chameleon coating in laboratory environment(humidity 40%-55%),dry nitrogen environment,cycled environment and oil lubrication condition were studied in this paper.The influence of different contact materials(steel balls and alumina balls)on the performance of PEO/Chameleon coatings is studied.In addition,the slip transition is studied with fretting tests with high load and small amplitude while the life of the coating is investigated with long cycle fretting tests in this thesis.In this thesis,two kinds of interface problems are studied based on the material interface properties.In the first type of interface problem,the influence of interfacial modification on the mechanical properties of composite materials in shape memory alloy composites is studied.To the second type of interface problem,the influence of the tribologically transformed structure(TTS)layer on the friction and wear properties of metal materials is studied.Through the study of these two kinds of interface problems,the influence of interface performance on material properties during static and dynamic process is obtained.