Preparation And Characterization Of Microstructure And Properties Of APC/A6061 Laminated Composites

Aluminium alloys have the advantages of lightweight,high specific strength,good plasticity and processing properties,and are widely used in important fields such as aerospace,transportation and defense and the military.However,the poor wear resistance of conventional aluminium alloys has limited their use in tribological applications.Amorphous carbon（APC）is an effective carbon material for improving the wear resistance of aluminium alloys due to its good lubricating effect and strong film-forming ability on the metal surface.However,how to achieve uniform dispersion of amorphous carbon in aluminium matrix composites,improve the interfacial bonding with the aluminium matrix,and overcome the soft nature of amorphous carbon,has become a difficult and critical point in the preparation of high-performance carbon/aluminium matrix composites.The metal laminate structure can give full play to the performance advantages of multiple materials and effectively improve the comprehensive performance of the material.Therefore,this paper proposes a new amorphous carbon/aluminium laminate composite and its preparation method,hydrothermal carbonization adsorption-vacuum hot press sintering process（HTCA-VHPS）,which provides theoretical support for expanding the development and application of new high-performance aluminum-based composites and has important theoretical significance.In this paper,APC/A6061 laminate composites were prepared by hydrothermal carbonization adsorption-vacuum hot press sintering process using A6061 aluminium alloy plates and glucose crystal powder as raw materials.The amorphous carbon and the microstructure of the composites were characterized by SEM,EDS,Raman spectroscopy,XRD and TEM,and the hardness,tensile properties and tribological properties of the composites were tested.The effects of glucose solution concentration and hydrothermal reaction time on the morphology and content of amorphous carbon on the surface of A6061 laminates were investigated to reveal the nucleation growth mechanism of amorphous carbon,explore the microstructure,mechanical properties and tribological properties of APC/A6061 laminates,and reveal the strengthening mechanism and wear resistance mechanism of the composites.The main research contents and results are as follows.After the hydrothermal carbonization and adsorption process,a uniform amorphous carbon film was formed on the surface of the A6061 laminate,and it was tightly bonded to the matrix.The morphology,structure,size and content of the amorphous carbon on the surface of the A6061 sheet could be controlled by varying the concentration of the glucose solution and the hydrothermal reaction time,with the concentration of the glucose solution being more favorable to the control.The nucleation growth mechanism of amorphous carbon is following the La Mer model.The content of amorphous carbon in the APC/A6061 laminated composites increased with increasing concentration of glucose solution.After vacuum hot-press sintering,the amorphous carbon is uniformly distributed between the layers of the composite,and the aluminium matrix diffuses into the amorphous carbon-rich composite layers,forming a good interfacial bond with the amorphous carbon.As the concentration of glucose solution increased,the interlaminar hardness,tensile strength and elongation of APC/A6061 laminated composites showed a trend of first increasing and then decreasing.When the concentration of glucose solution was 0.1 mol/L,the interlaminar hardness and tensile strength of the composites were up to 55.53 HV and 148.91 MPa,an increase of 9.6%and9.8%respectively;when the concentration of glucose solution was 0.3 mol/L,the elongation of the composites was up to 16.4%,an increase of 42.6%.The increase in interlaminar hardness of the laminated APC/A6061composites was mainly caused by the precipitation of Mg₂Si during high-pressure ageing,and the strengthening mechanisms mainly included fine grain strengthening,Orowan strengthening and diffusion strengthening.The increase in elongation is mainly due to the amorphous carbon film acting as a hindrance in the stretching process.As the concentration of glucose solution increases,the wear rate of the APC/A6061 laminated composites tends to decrease and then increase,while the friction coefficient gradually decreases.At a glucose solution concentration of0.3 mol/L,the wear rate was as low as 0.344 x 10^-5mm³/（Nm）,a decrease of65.94%compared to the A6061 laminated structural material.The improved wear resistance was attributed to the formation of a homogeneous amorphous carbon self-lubricating film on the wear surface.