Effect Of Interface Thickness And Interface Area Control On Thermal Conductivity Of Diamond-Cr/Cu Composites

The effect of interface thickness and interface area on the thermal conductivity of Diamond-Cr/Cu composites was studied by means of comparing experiment and numerical simulation results of Diamond-Cr/Cu composite as the research object.As to experiment,first of all,Cr was coated on diamond surface with using the method of salt bath plating,and Diamond-Cr/Cu composite materials with various thickness and different interface area were prepared by pressureless infiltration technique.Using the Desiccant Method,the relationship between the coating thickness and the coating temperature are calculated.Interfacial composition of diamond coating and Diamond-Cr/Cu composite and their microstructure were characterized by SEM,EDS,XRD and other methods.Finally,the bulk relative density and thermal conductivity of the composites were measured by Archimedes' s principle and thermal conductivity meter respectively.The numerical simulation was also used to study the effect of interface thickness and interface area on the thermal conductivity of the composites,and then compared the experimental values with simulation values.The research results of Salt bath plating of Cr shows that 0.376~1.388?m coating can be obtained by changed the salt bath plating temperature(750?~900?)on the surface of diamond particles with the same size.It can be obtained the interface layer with the proximity of 1.211?m while the diamond with different particle sizes were deposited at 850 ? for 1h.The diamond surface is well covered and the coating structure of diamond from the inside to the outside is diamond-CrxCy-Cr respectively.The research of Diamond-Cr/Cu composites prepared by pressureless infiltration shows that with the same size diamond,improving the temperature of salt bath plating can improve the wettability between diamond and copper by controling the thickness of diamond.With the increase of the thickness of the coating,the interface bonding ability of the composites enhances,and the internal transgranular fracture rate of the composites also increases.The interface cracks,pores and other defects are decreasing and the structure is more compact.For different diamond particle size of prepared composite materials,When the size of diamond is 230~270 mesh,the cracking phenomenon of the composites is due to the poor interfacial bonding.The fracture mode at the interface of diamond is mainly intergranular fracture.With the increase of the size of diamond,the fracture mode at the interface of diamond transform into transgranular fracture,and the transgranular fracture rate is increasing.EDS scanningof the interface shows that Cr gathers near the side of diamond interface and forms Cr3C2 and a small amount of Cr7C3.Composite material was realized the continuous transition of diamond-coating-copper at the interface.Diamond-Cr/Cu composite materials test results showed that with salt bath plating Cr temperature increased from 750?to 900?during salt bath plating of Cr,the well-covered coating made the bulk relative density of the composite increase,and it increase from 93.8% to 96%.While the thermal conductivity shows a trend of rising firstly and then decreasing.When the plating temperature is 800 ?,the thermal conductivity of the composite is the highest,which is up to 455W/(m·K).The thermal conductivity of Diamond-Cr/Cu composites with different size shows a rising trend when the size of the diamond increases,and the defects are decrease at the interface of the composites,the compactness of the composites increases from 89.7% to 96.1%.When the size of the diamond particles increase from 230~270 mesh to 80~100 mesh,the thermal conductivity of the composites will increase from 201W/(m·K)to 402W/(m·K).The ANSYS simulation results show that with the increase of coating thickness,the thermal conductivity of composites decreases.When the coating thickness increases from 0.376?m to 1.388?m,the thermal conductivity of the composites decreased from 652W/(m·K)to 440W/(m·K).When the coating is certain,and the size of the diamond particles reduce from 165?m to 52.5?m,the thermal conductivity of the composites decrease from 526W/(m·K)to 326W/(m·K).The comparison between the simulation and the experimental results show that the simulated values and experimental values tend to be consistent,but the simulated values are higher than the experimental values.The results show that the thermal conductivity of Diamond-Cr/Cu composites has a lot of room for improvement,which needs to be further optimized in order to obtain composite materials with more excellent performance.