Research On Interfacial Optimization And Thermal Conductivity Of Diamond/Copper Composites

As a new generation of thermal management materials, Diamond/Cu composites with good performance, have aroused widespread concern in resent years. In this paper,two methods of salt-bath plating W and doping W powder were applied to improve wettability between the diamond and copper. Diamond/Cu composites were prepared by pressureless-infiltration. The interfacial optimization was realized through various particle size diamond, different salt-bath plating process and controlling doping amount of W. The interface structure, components were characterizationed by SEM and XRD.The effect of interface number, thickness coating and interface components on microstructure and thermal conductivity of composites were also focused on.The fracture morphology of Diamond/Cu composite prepared by different diamond particle size show that failure mechanism is mainly intergranular fracture. With the increase of interface number, the interfacial thermal resistance of Diamond/Cu composite were 1.81×10-8m2K/W, 2.58×10-8m2K/W and 5.09×10-8m2K/W, respectively.The calculated thermal conductivity of composite were 793W/(m·K), 768W/(m·K) and697W/(m·K). With the increase of interfacial thermal resistance, calculated thermal conductivity decreased. Further, the practical thermal conductivity were 578W/(m·K),525W/(m·K) and 441W/(m·K), which are similar to the change regular pattern of calculated thermal conductivity. With the extension of W plating time, the thickness of the coating increased. By weight method and numerical calculation, the thickness of W coating on diamond were 1.18μm, 1.72μm, 2.48μm, and 3.24μm, respectively. The interfacial thermal resistance of Diamond/Cu composite were 0.86×10-8m2K/W,1.26×10-8m2K/W, 1.81×10-8m2K/W and 2.35×10-8m2K/W, respectively. When the coating thickness of diamond and interfacial thermal resistance increased, the calculated thermal conductivity of composite declined. The calculated value are 827W/(m·K),812W/(m·K), 793W/(m·K) and 775W/(m·K). But the experimental results indicate that the practical thermal conductivity of composite were 280W/(m·K), 473W/(m·K),578W/(m·K) and 532W/(m·K), respectively. Which increase firstly and then decrease with the increase of coating thickness.In the situation of composites material prepared by different doped W amount.When the content of W reaches 10% volume fraction the interface bonding reaches the best. Phase Diagram and XRD analyzed showed that compositional gradient existed at the interface. The interface structure is is composed of Cu0.4W0.6-W2C-WC-Diamondphase from outside to inside. Each phase mutual diffusion at the interface, and no clear boundaries. The bending strength of Diamond/Cu composite prepared by different W doped amount are 211 MPa, 265 MPa, 327 MPa, 353 MPa and 358 MPa. Thermal diffusivity are 45mm2/s, 87mm2/s, 93mm2/s, 114mm2/s and 87mm2/s. Thermal conductivity are 236W/(m·K), 381W/(m·K), 423W/(m·K), 456W/(m·K) and350W/(m·K), respectively.Two methods of salt-bath plating W and doping W powder were compared in this paper. The composites fabricated by salt-bath plating W retained higher thermal conductivity, however, the plating and separation processes were complicated. The latter process is simple, but how to control the distribution of W to improve the thermal conductivity still need further explored.