TC4 Surface Organic Modification And Its Effects On The Adhesive Performance Of TC4/PEEK Interface

Titanium/carbon fiber reinforced PEEK resin(Ti/Cf/PEEK)laminates as a novel fiber mental laminates(FMLs),combining the performance advantages of its constituent components and possess many outstanding properties such as high specific strength and specific modulus,excellent fatigue resistance,temperature resistance,and damage tolerance,which all provides more prospect and space for the development of aerospace materials.Nevertheless,in Ti/Cf/PEEK laminates structure,the interface of metal/resin(Ti/PEEK)is relatively weaker,which affects the transfer of interface stress and finally severely restricts the application of laminates Therefore,it is of great engineering significance to seek new methods to improve high-temperature interface performance.Firstly,schiff base titanium complex was prepared and loaded respectively on pristine,anodized,sand blasted and sand blasted-anodized TC4 sheets.Differently modified TC4 sheets were analyzed through Fourier Transform Infrared Spectroscopy(FT-IR),Thermogravimetry/Differential Scanning Calorimetry(TG/DSC),Scanning Electron Microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Contact angle measurements.The results showed that schiff base complex with good temperature resistance;anodized TC4 sheets possessed highest surface energy;different pretreatments had a great impact on the morphology of modified TC4 sheets,among them,the surface morphologies of anodized TC4 sheets before and after loading are more conducive to improving the interfacial properties of laminate.Secondly,pretreated TC4 sheets were grafted by SPEEK in order to compare and analyze different organic modification methods.FT-IR,SEM and Contact angle measurements results showed TC4 sheets pretreatments and sulfonation degree of SPEEK well affected the surface properties of modified TC4 sheets.It was manifested that TC4 sheets after loading had highest surface energy and the surface energy slightly improved with the increase of sulfonation degree.The morphology all changed by grafting,anodized TC4 sheets after grafting,SPEEK wrapped the original spherical structure and filled in the spherical clearance;sand blasted-anodized TC4 sheets after grafting,SPEEK mainly filled the holes of spherical network structure.Finally,adhesive performance between modified TC4 sheets and PEEK were investigated(at room and high temperature)through single lap shear and interlayer shear test.At room temperature,single lap shear test showed anodized TC4 sheets after loading or grafting SPEEK with 40% sulfonation degree had better bond strength,respectively reached to 47.49 MPa and 40.77 MPa.Single lap failure sections were observed by macroscopically and SEM,which showed all samples failure modes were categorized as mixture modes of cohesive and interfacial failures.Cohesive failure zones of anodized TC4 sheets after loading or grafting SPEEK with 40% sulfonation degree respectively reached to 95% and 93%,the topography of failure section similared to shear cups and cones.Interlayer shear test showed pretreated TC4 sheets had higher interlayer shear strength after loading schiff base titanium complex,sand blasted-anodized TC4 sheets after loading or grafting SPEEK with 40% sulfonation degree had more excellent strength,reached to 73.1493 MPa and 72.19 MPa.At high temperature,single lap shear test showed the ductility and adhesive strength increased at 70 ?;with the increase of temperature,adhesive layer gradually softened and load carrying capability decreased,finaly led to interfacial strength declined gradually.The surface properties were combined with interface test to analyze the mechanism of enhancing the interface by two organic methods.According to surface properties and mechanics test results,the interface enhancement mechanism of the two organic modification methods was established.