Structure and Performance of Diamond Coating for Graphite Mold Precision Machining
LI Hong*, XU Wei, SU Yifan, LIN Songsheng, DAI Mingjiang, SHI Qian
The Key Laboratory of Guangdong for Modern Surface Engineering Technology, National Engineering Laboratory for Modern Materials Surface Engineering Technology, Guangdong Institute of New Materials,Guangdong Academy of Sciences, Guangzhou 510650, China
Abstract: Diamond coating has ultra-high hardness and wear resistance which was close to that of natural diamond, and is considered to be an ideal tool coating material for precision machining of graphite molds. The bonding force between the diamond coating and the substrate, and the surface state of the coating are the keys to the quality and efficiency of high-speed dry cutting. The pre-treatment of the diamond coating and the coating process are important factors that affect the property of the diamond-coated tool. This article used acid-alkali-acid three-step method to pre-treat the cemented carbide materials based on hot-wire chemical vapor deposition technology. Atmospheric flow rate and high pressure deposition process were used to deposit diamond coating on the tool substrate. Scanning electron microscope (SEM), atomic force microscope (AFM), Raman spectroscopy (Raman), X-ray diffraction spectroscopy (XRD) were used to analyze and characterize the coating microstructure and phase structure. The sand blast test was used to test the erosion resistance of the diamond coating, and the graphite mold cutting test was used to characterize the cutting performance of the diamond coated tool. The results show that the diamond coating has a typical octahedral structure, the coating and the substrate are closely combined without obvious pores, the surface roughness of the diamond coated tool is about 150 nm, the content sp3 is more than 98%, the coating hardness is higher than 90 GPa, diamond coating grows preferentially along the (111) plane, the erosion resistance time is greater than 150 s (0.5 MPa, 120 mesh), the roughness of the processed surface is less than 1μm after high-speed cutting graphite mold for 2 h, reaching the level of imported tools. There is a small amount of chipping on the rake face of the tool after the cutting. Therefore, the wear of the rake face is the main form of wear for processing graphite molds.
李洪, 许伟, 苏一凡, 林松盛, 代明江, 石倩. 面向石墨模具精密加工的金刚石涂层结构及性能[J]. 材料导报, 2021, 35(14): 14030-14034.
LI Hong, XU Wei, SU Yifan, LIN Songsheng, DAI Mingjiang, SHI Qian. Structure and Performance of Diamond Coating for Graphite Mold Precision Machining. Materials Reports, 2021, 35(14): 14030-14034.
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