Study On The Regulation Mechanism Of Interface Structure On Interfacial Thermal Conduction For High Thermal Conductivity Diamond/Metal Matrix Composite

With the rapid development of the field of electronic information,the power density carried by electronic components is getting higher and higher,and the heat production per unit area has also increased significantly,seriously affecting its work efficiency and service life,so it is very important to transmit the generated heat in time through heat sink and other heat dissipation materials.Diamond and aluminum,copper and other high thermal conductivity metals composite can theoretically prepare a new generation of heat sink materials with high thermal conductivity and low thermal expansion coefficient,but it’s extremely low interfacial compatibility seriously reduces the interfacial thermal conductivity,and the actual thermal conductivity is much lower than the theoretical value.The introduction of carbide intermediate layer between diamond and metal matrix to regulate the interface structure can effectively improve the interface thermal conductivity,but the regulation mechanism of this process is not clear.Therefore,the research hotspot in this field has become a research hotspot to study and clarify the correlation between the interface structure of diamond/metal matrix and the interface thermal conductivity,and then realize the optimal regulation of its interface.In this paper,the interface formed by diamond,aluminum,copper and other materials with significantly different characteristics is taken as the research object,and the interface structure is regulated by introducing a metal and its carbide intermediate layer at the interface,and then the interface thermal conductivity is adjusted.Based on Auger electron spectroscopy(AES),focused ion beam(FIB),scanning transmission electron microscopy(STEM)and other technologies to characterize the interface structure,the interface thermal conductivity was directly measured by time domain heat reflection(TDTR),so as to construct the correlation between interface thermal conductivity and interface structure.In this paper,Al/Cr/Diamond nanolayered structures were prepared by magnetron sputtering to prepare Al/Cr/Diamond nano-layered structures by magnetron sputtering on single-crystal diamond substrates sequentially as interface model samples of diamond/aluminum matrix composites,and then heat treated at 873 K at different times.Then,the interface structure of each sample at different heat treatment stages was characterized by AES,STEM and other technologies,and the interfacial thermal conductivity of each sample was directly measured by TDTR technology.The results showed that Cr3C2 phases were generated at the interface after heat treatment at 873 K,and with the extension of heat treatment time,the number of Cr3C2 phases continued to increase,and the interfacial thermal conductivity first increased and then decreased(the peak value of 436.66 MW/(m2·K)was reached at 120 min,which was 60%higher than that of the untreated sample).This is because when a small amount of Cr3C2 phase is generated at the interface,the interfacial bonding strength can be improved,thereby effectively improving the interfacial thermal conductivity.With the increase of thickness,the thermal resistance introduced by the Cr3C2 phase with low intrinsic thermal conductivity continues to increase,which in turn leads to a decrease in the interface thermal conductivity of the composite.Subsequently,Cu/W/Diamond and Cu/WC/Diamond nanolayered structures with different intermediate layer thicknesses were prepared by magnetron sputtering to deposit nano-W(WC)and copper films on single-crystal diamond substrates sequentially as interface model materials for diamond/copper matrix composites,and their interfacial thermal conductivity was measured based on TDTR technology to explore the influence of different intermediate thicknesses on interfacial thermal conductivity at the nanoscale.The results showed that the interfacial thermal conductivity values of Cu/W/Diamond and Cu/WC/Diamond samples showed a trend of first increasing and then decreasing.Among them,the former reaches a maximum interface thermal conductivity of 100.4 MW/(m2·K)when the thickness of the intermediate layer is 20 nm,and the latter reaches a maximum of 86.8 MW/(m2·K)when the thickness of the intermediate layer is 15 nm.This shows that the interface thermal conductivity of the composite does not increase monotonically with the decrease of the thickness of the intermediate layer,but there is a thickness similar to the average free path of the thermal carrier in the middle layer to make the interface thermal conductivity reach the highest value.When the thickness of the intermediate layer is lower than this threshold,it will negatively affect the thermal carrier coupling behavior in the interface transition region,resulting in the decrease of the interface thermal conductivity with the decrease of thickness.When the thickness of the intermediate layer is higher than this threshold,the lower intrinsic thermal conductivity of the intermediate layer also causes the interface thermal conductivity to decrease with the increase of thickness.In summary,by constructing Al/Cr/Diamond and Cu/W(WC)/Diamond interface model materials,this paper reveals the influence mechanism of diamond-reinforced high thermal conductivity metal matrix composites on interface thermal conductivity,which provides theoretical support for the optimal regulation of their interface structures.