Preparation And Characterization Of Copperized C_f Reinforced Copper Matrix Composites

In recent years, carbon fibre reinforced copper matrix composite(C_f/Cu composite) has become a most important kind of carbon fibre reinforced metal matrix composites because of its good electrical and thermal conductivity, besides, good ability to reduce friction and wear,in addition, lower thermal expansion coefficient. However, there is a bad wettability and adhesion between C_f and Cu, which largely lowers properties of C_f/Cu composite. Therefore,there are some key basis to improve the adhesion of C_f and Cu, and prepare C_f/Cu composite with excellent properties, as well as research its mechanical and tribology properties.As it is easy to be agglomerationof powders in the process of mixing carbon fibers with Cu powders, then which gives bad effect on the composite’s properties, it has a great significance to improve uniform dispersion of carbon fibers when mixing with Cu powder and study on the C_f/Cu composite. To get uniformly dispersed C_f/Cu containing a large volume fraction of short C_f, first, this paper studied the electro-chemical method to prepare copperized C_f. Then the single fiber tensile tests for raw C_f and copperised C_f were taken on their interfacial bonding strength, while the fracture process was observed by in-situ tensile test.Based on that, C_f/Cu composites with different volume fraction of C_f were prepared, and the effects of the additon volume fraction of C_f in the composite on the hardness were also researched. Afer that, there was a comparison between Cu and C_f/Cu composite about their mechanical and morphology properties. At last, the following findings and conclusions are now reached:First of all, with electro-chemical method, a parallel copper fossil was used as the electrode instead of long cf bundle to prepare clean and smooth copperized carbon fibres. Then there was a single fibre tensile test whose results show that the Cu coating creates discontinuous fractures, which causes fluctuations in the load-displacement curve. It figures that the tensile strength of copperized C_f is not improved in comparison to raw C_f and it means it’s still mechanical bonding between coating and substrate.Secondly, C_f/cu composites with C_f of 46 vol%(sample 1), 31 vol%(sample 2),20 vol%(sample 3) and 18 vol%(sample 4) were respectively made by hot sintering the copperized C_f with correspondent 2 V, 3 V, 4 V and 5 V, 30 min. Meanwhile, another C_f/cu composite was made by mixing Cu powder with non-copperised C_f, and the C_f’s volume fraction of which was still 46%(sample 5). On the study of structure uniformity, hardness,density and mechanical properties of those mentioned samples, it proves that the hardness firstly increases and then reduces with the increasing volume fraction of C_f. What’s more, theproperties of sample 1, 2, 3 and 4 are all better than sample 5.Thirdly, there was an elementary study on the dry tribological properties. The findings indicate, when it’s paired with Si3N4, the wear rate of the C_f/Cu composite is higher than Cu,but the friction coefficient is lower and more stable under the dry tribological condition.