Effects Of Graphene Contenton Frictional Wear Properties And Wear Mechanism Of Graphene/Al-Si Composites

As one of the new materials with the most outstanding performance discovered by human in the 21 st century,Gr-graphene has the reputation of "the King of new materials" for its high strength,high elastic modulus and excellent thermal and electrical conductivity.Past researchers have add graphene as wild phase to the metal,polymer,inorganic compounds,in order to investigate whether the excellent properties of graphene after forming composite materials will be inherited,finally get the test result is yes-graphene can be used as a kind of excellent phase change composites reinforced the various aspects of performance.Compared with ordinary steel and iron materials,hypereutectic al-SI alloy is characterized by low density,low thermal expansion coefficient and high specific strength.It is a common material with excellent comprehensive performance in production and life,and is widely used in aerospace,automobile,electronic packaging and other fields.However,because the Si content in hypereutectic al-SI alloy is far higher than that in eutectic point Si content,the properties of al-SI materials are affected by the size and shape of Si particles in the alloy.In order to obtain al-SI materials with excellent properties,different amounts of Gr were added to al-18SI-3Cu-mg alloy powder in this study to prepare grapher-reinforced al-Si matrix multi-element composites,and the effect of graphene addition on the friction and wear properties of Gr/ al-18SI-3Cu-mg multi-element composites was studied.Using the powder metallurgy method for the preparation of Gr/Al-Si composite material,through adding different weight percent of graphene obtained four groups of different composition of Gr/Al-Si composite material sample,the sample for the tensile properties of composite material density,hardness measurement,measurement,performance measurement of thermal conductivity and friction and wear performance measurements,contrast different graphene addition amount of Gr/Al-Si composite material performance influence mechanism;Scanning electron microscope,X-ray diffractometer and other test equipment were used to analyze the microstructure and internal composition of composite materials.The test results show that the graphene with Al substrate interface is good,has the refining effect of Si particles,Si particles diffuse distribution of Gr/Al-Si-3 cu-18 Mg of multivariate composite material hardness is improved,the Gr/Al-Si composite material hardness value as graphene quality percentage increase(0%,0.3%,0.5,0.7%)presents the downward trend after rising first,anti-wear performance is also improved.On the MDW-02 reciprocating friction and wear test machine,set the test force20 N,test stroke 20 mm,test time 10 min,and test frequency 2HZ.The friction and wear test of Gr/ al-SI composite was carried out,and the friction and wear curve of friction coefficient changing with time was obtained.By observing the friction and wear curve and the hardness value of the composite,it was found that when the amount of graphene added was 0%,0.3%,0.5% and 0.7%,the hardness value of the composite first increased and then decreased.When the graphene content was 0.5%,the hardness value had the highest friction coefficient,which was 84.8HB and 0.48 respectively,and the friction coefficient was 28% lower than that without graphene addition.At the same time,fractal theory is used to analyze the appearance of wear marks,and the fractal dimension of wear marks is obtained by programming Matlab.As can be seen from the size of fractal dimension,when the amount of graphene added is 0.5%,the fractal dimension is the smallest,and Gr/ al-SI composite has the best wear resistance.The morphology of the wear marks was observed by scanning electron microscope(SEM)and laser confocal microscope.It was found from THE SEM image and the three-dimensional image of laser confocal microscope that when the graphene content was 0.5%,the wear degree of the sample was minimal.Therefore,when the graphene content in the composite material is 0.5%,the hardness of the sample reaches the maximum of 84.8HB,which is 12.2% higher than that of the sample without adding graphene.When the graphene content was 0.5%,the friction coefficient of the composite was the smallest,0.48.