| As one of the lightest metal structural materials,magnesium alloys exhibit low density,high specific strength and specific stiffness,excellent damping performance and electromagnetic shielding,good thermal conductivity and formability and easy recovery.Magnesium alloys is widely used in transportation,aerospace,electronic communications and other industries.However,the poor corrosion resistance of magnesium alloy seriously restrict its applied range.Fiber metal laminates?FML?combine the advantages of metal materials and traditional fiber reinforced composite material without their deficiency,with high damage tolerance,lightweight,fire resistance,corrosion resistance and other advantages.Such as glass reinforced aluminum laminates?GLARE?,which has been successfully applied in the plane of Airbus A380 and Boeing 777.As excellent lightweight materials,magnesium alloy and glass fiber reinforced resin composite have good complementarity on strength,corrosion resistance and damage tolerance.The two materials combination can create new materials or new properties.This paper draws on the high performance technology of GLARE used in aerospace and high efficiency preparation method of aluminium-plastic plate and copper clad laminate,devote oneself to develop the supporting technology of glass giber reinforced resin/magnesium?GFRR/Mg?laminate.It is expected that develop a glass giber reinforced resin/magnesium laminate which has lightweight and good properties,and open up a new way of high quality and low cost anti-corrosion for magnesium alloy in this thesis.Surface modification of magnesium alloy,structure design,interfacial characteristics analysis and control of fiber reinforced resin/magnesium alloy laminates,and corrosion behavior and damage behavior of laminated composites were mainly studied in this thesis.The main research work and results are as follows:1.The importance of surface properties of magnesium alloy plate for forming method of fiber metal laminate was analysed and high quality,dense and uniform conversion coating was obtained on the surface of magnesium alloy by phosphating modification and permanganate-phosphating modification technology.Chemical modification experiment and structure observation and analysis of chemical conversion coating showed that the best time of phosphating modification and permanganate-phosphating modification on magnesium alloy surface was 5 minutes,here the phosphate film on the magnesium surface is a double layers structure with loose porosity up-layer and dense and homogeneous under-layer and the permanganate-phosphate film is regular dense net-like monolayer.The main chemical composition of phosphate film were Zn3?PO4?2·4H2O?Mg3?PO4?2?MgMoO4?ZnO,where the main chemical composition of permanganate-phosphate film were Mg3?PO4?2?MgMn2O4?AlPO4.The dynamic wetting behaviour showed that the surface energy of magnesium modified by phosphating modification and permanganate-phosphating modification were increased 50%and 64.6%than abraded-only magnesium,respectively.The surface roughness of magnesium has little effect on the wettability of magnesium alloy modified by phosphating modification and permanganate-phosphating modification.2.The structure of the two kinds of glass giber reinforced resin/magnesium laminates were studied and designed and the forming methods were experimented in this thesis.Two types of laminates include a?2+3?glass fiber reinforced resin/magnesium laminate?two layers glass giber composite and three layers magnesium alloy alternately?in order to achieve the lightweight and good properties,and a?2+1?glass fiber reinforced resin/magnesium laminate?two layers glass giber composite coated one layer magnesium alloy?in order to achieving high corrosion resistance of magnesium alloy.The laminated forming process studied in this thesis include magnesium alloy and glass giber reinforced resin direct bonded and hot press forming and use a modified polypropylene hot melt film indirect bonding and hot press forming.The SEM images of the interface of laminates showed that the phosphate film thickness was about 20?m and the permanganate-phosphate film thickness was about 6?m in the laminates based on magnesium alloy plate modified by chemical method.The indirect bonding glass fiber reinforced resin/magnesium laminate used modified polypropylene interleaf had a better bonding interface and bonding effect than the direct bonding type.3.The mechanical properties of the?2+3?glass fiber reinforced resin/magnesium laminates were experimentally analyzed and the influence of surface modification of magnesium alloys and bonding types of laminates on the mechanical behavior of the?2+3?laminates was revealed in this thesis.The mechanical behavior showed that the tensile strength,bending strength,inter-laminar shear strength and interfacial fracture energy of the?2+3?glass fiber reinforced resin/magnesium laminate used modified polypropylene interleaf indirect bonding were 8.7%,4.5%,30%and 120%higher than direct bonding type,respectively.The AZ31B magnesium alloy had better corrosion resistance property in a short time when modified by phosphating modification and permanganate-phosphating modification,and provided enough time for subsequent forming process.The interfacial fracture energy of direct bonding?2+3?laminates based on magnesium with phosphating modification and permanganate-phosphating modification were 58%and 43%higher than laminates based on magnesium with abraded-only,respectively,where the value of indirect bonding laminate were 37%and24.5%,respectively.The surface roughness of magnesium alloy can affect the interfacial adhesion properties of the?2+3?glass fiber reinforced resin/magnesium laminate.The inter-laminar shear strength and interfacial fracture energy of laminates based on magnesium abraded by#120 sanding?Ra is 0.92?m?were increased by 13%and 18%than#2000 sanding?Ra is 0.23?m?.4.The corrosion behavior of the?2+1?glass fiber reinforced resin/magnesium laminates were systematic studied and good corrosion resistance of magnesium alloy was obtained in this thesis.The water absorption test showed that the water absorption rate per unit area and water absorption percentage relative to sample weight of the?2+1?glass fiber reinforced resin/magnesium laminates were 18.6 g/m2 and 0.8738%,respectively.The full immersion corrosion test showed that the hydrogen volume per unit area of“2+1”glass fiber reinforced resin/magnesium laminates immersed for 24hours was 0.008 ml/cm2 and was only 0.18%of AZ31B magnesium under the same conditions.After immersion for 15 days,the tensile strength of the?2+1?laminates was still 90%of original,whereas the tensile strength of AZ31B magnesium alloy was not measurable.After immersion for 25 days,the tensile strength of the?2+1?laminates was still 62.6%of original.Electrochemical corrosion test showed that the corrosion potential of“2+1”glass fiber reinforced resin/magnesium laminates was about-0.646V and positive shifted about 0.927 V than AZ31B,and the corrosion current density of“2+1”laminates was about 1.05×10-3?A/cm2 and declined by 5 orders of magnitude than AZ31B magnesium alloy. |
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