| With the development of high-power electronic components and large-scale integrated circuits,high-performance diamond/Cu composites are welcomed in electronics technology fields,which have high thermal conductivity and low expansion coefficient.The weak interface between diamond and copper in the diamond/Cu composite that inhabit it's application in the electronics industry.In this paper,the diamond particles were coated by copper or tungsten using electroless plating and thermal diffusion method,respectively.The Diamond/Cu composites have been sintered by spark plasma sintering and hot press sintering,respectively.Phase composition,thermal conductivity,thermal expansion coefficient and bending strength of the Diamond/Cu composites were checked by x-ray diffraction,scanning electron microscope,raman spectrometer,thermal conductance instrument,thermal expansion instrument and universal testing machine.The effects of raw material formulation,sintering method and sintering temperature on the microstructure,relative density,flexural strength,thermal conductivity and thermal expansion coefficient of the Diamond/Cu composites were studied.The main results are as follows:?1?The diamond particles can be coated evenly by Cu using the electroless plating method.Then the Cu coating diamond particles were mixed with copper powders and sintered by spark plasma sintering at 900-1050 ? under a pressure of 40MPa.The relative density of the Diamond/Cu composites first increased and then decreased with the sintering temperature increasing.The sample that was sintered at1000 ? had the highest relative density,which value was 98.76%.The thermal conductivity of the Diamond/Cu composites first increased and then decreased with the amount of diamond increasing.When the diamond content was 55 vol.%,the thermal conductivity reached the maximum value of 353.95 W/?m·K?.?2?The diamond particles can be coated evenly by tungsten using the thermal diffusion method.Then the tungsten coating diamond particles were mixed with copper powders and sintered by spark plasma sintering at 900-1050 ? under a pressure of 40 MPa.The relative density,thermal expansion coefficient,thermal conductivity,flexural strength of the Diamond/Cu composites first increased and then decreased with the sintering temperature increasing.The above properties of the Diamond/Cu composites decreased with the amount of the diamond increasing.The thermal conductivity of the sample that content of 50 vol.%diamond sintered at 950? reached the maximum value of 579.67 W/?m·K?.The relative density of this sample was 98.18%,the flexural strength was 127.33±4.73 MPa and the thermal expansion coefficient was 7.78×10-6/K.The interfacial thermal resistance of this sample was calculated by Hasselman-Johnson model,which was R=3.1×10-8 m2·K/W.These indicated that the introduction of tungsten elements effectively improved the bonding strength of the interface between diamond and copper,reduced the interfacial thermal resistance and improve the thermal conductivity of the composite.?3?Then the tungsten coating diamond particles were mixed with copper powders and sintered by hot press sintering at 950-1100 ? under a pressure of 30MPa.The relative density,thermal expansion coefficient,thermal conductivity,flexural strength of the Diamond/Cu composites first increased and then decreased with the sintering temperature increasing.The above properties decreased with the amount of the diamond increasing.The thermal conductivity of the sample that content of 50 vol.%diamond sintered at 1050 ? reached the maximum value of364.24 W/?m·K?.And the relative density of this sample was 96.39%,the flexural strength and the thermal expansion coefficien of this sample were 123.00±2.83 MPa and 6.86×10-6/K,respectively.All the above properties of this sample were lower than the properties of the Diamond/Cu composites with the same formula sintered by spark plasma sintering.Spark plasma sintering could purify the grain boundary,promote the bonding of diamond and copper interface. |
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