Lightweight diamond/Cu interface tuning for outstanding heat conduction

With rapid developments in the field of very large-scale integrated circuits,heat dissipation has emerged as a significant factor that restricts the high-density integration of chips.Due to their high thermal conductivity and low thermal expansion coefficient,diamond/Cu composites have attracted considerable attention as a promising thermal management material.In this study,a surface tungsten carbide gradient layer coating of diamond particles has been realized using comprehensive magnetron sputtering technology and a heat treatment process.Diamond/Cu composites were prepared using high-temperature and high-pressure technology.The results show that,by adjusting the heat treatment process,tungsten carbide and di-tungsten carbide are generated by an in situ reaction at the tungsten–diamond interface,and W–WC–W_(2)C gradient layer-coated diamond particles were obtained.The diamond/Cu composites were sintered by high-temperature and high-pressure technology,and the density of surface-modified diamond/Cu composites was less than 4 g cm^(-3).The W–WC–W_(2)C@diamond/Cu composites have a thermal diffusivity as high as 331 mm^(2)s^(-1),and their thermal expansion coefficient is as low as 1.76×10^(-6)K^(-1).The interface coherent structure of the gradient layer-coated diamond/copper composite can effectively improve the interface heat transport efficiency.

Evolution behavior of phase and performance in Ni-based coating layer based on high temperature thermal field

Effect of post-welding heat treatment on the microstructure and properties of BNi-2 brazing coating was analyzed. The phase transformation in the heat treatment process was analyzed by high temperature metallographic microscope, scanning electron microscope and X-ray diffraction, and the microhardness after the post heat treatment was tested by microhardness tester. The results show that the microstructure of brazing BNi-2 brazing coating is mainly CrB phase, Ni solid solution phase and eutectic phase of Ni_(3)B and Ni_(3)Si. After brazing,the overall hardness value is higher, generally higher than 510 HV, and the microhardness in some areas is higher than 700 HV. After quenching, the solid solution phase of Ni increased, and the eutectic phase of Ni and Ni_(3)Si decreased, leading to the softening of the brazing coating, the area whose microhardness in the range of 342 HV–454 HV increased. After tempering the brazed coating samples, the eutectic phases of Ni and Ni_(3)Si grew and the hardness recovered, but the overall hardness distribution was still lower than the brazing one. The results of the brazing post-heat treatment test show that the post-welding heat treatment will bring adverse effects on the hardness distribution of the coating, which may affect the wear resistance of the coating.

Study on the characteristics of PCBN materials at home and abroad

The main developments and research of polycrystalline cubic boron nitride(PCBN)products are reviewed based on categories,binders,microstructure homogeneity and impact toughness.Moreover,new materials such as nanopolycrystalline CBN and non-binder PCBN are introduced,including characteristics and future applications.