Preparation And Performance Study Of Cu-based Powder Metallurgy Friction Materials Containing Ni/graphene

In order to improve the comprehensive performance of Cu-based powder metallurgy(PM)friction material,graphene is used as reinforcing filler to improve its comprehensive performance to meet requirements of the current car in the increasingly poor braking conditions.At the same time,Ni is added to the graphene to improve the binding force between graphene and Cu in two ways.The performance of nickel/graphene(Ni/G)composites prepared by two methods was characterized and compared.The effect of content of Ni in Ni/G on the comprehensive properties of friction materials was studied by adding Ni/G with different content of Ni to the friction material.Then,the effect of content of Ni/G on the mechanical properties and tribological properties of Cu-based PM was studied by adding Ni/G as the reinforcing filler with the best content of Ni.The results show that:(1)The number of payer of prepared graphene is 3-5.(2)Ni/G can be prepared by oxidation-reduction method and electroless plating at the same time.The distribution of Ni particles in Ni/G prepared by different ways is terriblly different,the distribution of Ni particles in Ni/G prepared by electroless plating method is more uniform and the loading is higher.When the molar ratio of Ni to carbon was 1.5: 1,and the molar ratio of nickle-salt to BH4 Na was 2: 3,the mass fraction of Ni in Ni/G can be maximum,which is 38.27%.(3)With the increase of content of Ni in Ni/G,the density of the material increases gradually.(4)With the increase of content of Ni in Ni/G,the hardness,tensile strength and flexural strength of the friction material show a parabolic trend.When the content of Ni in Ni/G is37.04%,the size of hardness,tensile strength and flexural strength of the friction material reached the maximum(45.3HB,230 MPa,492MPa).At the same time friction material has the most stable friction coefficient and best wear resistance.(5)Cu-based PM friction material with different content(0%,0.25%,0.5%,0.75% and1%)of Ni/G,the content of Ni in Ni/G is 37.04%,were prepared.The results show thatthe hardness of Cu-based friction material with Ni/G is improved by 7.9%-18.2%,the tensile strength is increased by 24.3%-46.1%,the flexural strength is improved by7.9%-62.9%.With the increase of content of Ni/G,the hardness,tensile strength and flexural strength of the composites increased first and then decreased.The mechanical properties of the sample are the best,when the content of Ni/G is 0.75% in the composites.Its hardness,tensile strength and bending strength values were 46.8HB,241 MPa,518MPa.(6)The stability and wear resistance of the friction coefficient of the Cu-based powder metallurgy friction material with Ni/G were improved.The wear rate of friction material containing Ni/G filler is 6%-76%(20N),67.5%-81.25%(80N)less than that of Ni/G without Ni/G at low speed(500r/min).The friction coefficient of the material decreases with the increase of the load.The friction coefficient of the material with Ni/G under different load is reduced by 21.3%-76.9%(20N),43.4%-71.1%(80N)at high speed(2500r/min).The sample with Ni/G(0.75%wt)has the most stable coefficient of friction and best wear resistance in the whole stage of friction experiment.