| Graphene is a new type of two-dimensional atomic crystal materials,it has a high electrical conductivity and thermal conductivity,large specific surface area,high young’s modulus and tensile strength,the young’s modulus of single-layer graphene is 1 TPa and the tensile strength of graphene is 130 GPa,which as nano enhanced body and solid lubricating materials can effectively reduce the friction coefficient of metal materials,significantly enhance the abrasion resistance.So graphene as a second phase are expected to further improve the mechanical properties such as the hardness,strength and tribological performance.In this paper,We combined the powder metallurgy method and chemical vapor deposition method in-situ fabricate graphene/nickel(G-Ni)based composite materials.Through change the parameters such as carbon source,graphene growth time and temperature,we prepared of high performance and different G-Ni composite materials.Study the technological parameters of temperature,carbon source concentration and time on mechanical properties and tribological properties of composite materials.X-ray diffraction(XRD)and scanning electron microscope(SEM)results showed that graphene evenly dispersed in the matrix of nickel,and as the preparation temperature,carbon source concentration and time increased,the matrix of nickel grain size slightly increased.Raman spectroscopy(Raman),and transmission electron microscope(TEM)analysis results show that the in-situ growth of graphene layers is about 4 to 6 layers,and through control the carbon source content,you can get almost no defects of graphene.Using micro hardness tester,UMT-2 multifunctional friction testing machine and microcomputer control electronic universal testing machine test the hardness,tensile strength and tribological properties respectively Results show that when the carbon content is 240 mg,temperature is 1100 ℃,time is 60 min,composite material hardness and tensile strength are 107 MPa and 370 MPa respectively.Compared pure nickel,hardness and tensile strength increased 1.8 and 4.2 times,its friction coefficient and wear rate as low as 0.48 and 6.9×10-5mm3/Nm.When carbon content is 240 mg,temperature is 1100 ℃,time is 40 min,the friction coefficient and wear rate of the composite were 0.38 and 6.0×10-4mm3/Nm.Based on the properties of the porous structure of composite materials,the high porosity of G-Ni composite material into PET-OA and PAO10 lubricating grease,from oily G-Ni composite materials was prepared.Solid-liquid composite lubrication effectively reduces the G-Ni friction coefficient and wear rate of the composite material.Including the oily PET-OA/G-Ni composite material as low as 0.29,the friction coefficient from oil PAO10 / G-Ni composite wear rate as low as 6.6×10-5 mm3 / Nm.To sum up,the organic combination of powder metallurgy and CVD technology,in the process of powder metallurgy sintering,with solid carbon source for the body,the nickel matrix in situ growth graphene,G-Ni composite materials was prepared.The results showed that graphene not only effectively improve the G-Ni mechanical properties such as hardness and tensile strength of the composite material,but also can significantly reduce the friction coefficient and wear rate. |
