Key factors affecting the performance of diamond wire drawing die coatings

Abstract： Diamond has high hardness, elastic modulus and other properties, irreplaceable role in the tool market, for the relevant enterprises to bring stable earnings.The diamond wire drawing die is extensively employed in the metal drawing and strand tightening fields, primarily due to its remarkable hardness.  This attribute enables the die to withstand the immense pressures and friction encountered during the drawing process, ensuring that the wires are pulled through with precision and minimal resistance.  The high hardness of the diamond not only facilitates the reduction of the wire diameter but also contributes to the integrity and strength of the finished product. The metal drawing properties of diamond coating are closely related to the microstructure.
【Objectives】In this research, the selection of two pivotal temperature 900℃ and 950℃, was based on extensive prior experimentation. These temperatures were chosen for their significant impact on the material's properties and the outcomes of the processes. The effect of the two processes on microstructure and the difference of failure mechanism were studied.
【Methods】Based on the simulation method, the temperature distribution in the drawing die is analyzed, Scanning Electron Microscopy (SEM) is employed to observe the surface topography of diamond drawing die at high magnification. X-ray Diffraction (XRD) analysis is then conducted to investigate the crystallographic structure of the diamond drawing die. Additionally, Raman spectroscopy is used to analyze quality of the diamond drawing die.
【Results】The results show that the temperature gradient inside the die is small so the direct effect of temperature on diamond coating deposition is small. High temperature can promote carbon active groups to enter the compression and sizing regions to form nanodiamonds, while lower temperature will weaken the diffusion ability of carbon active groups and form micrometer diamonds in the compression and sizing regions. Nanometer diamond coating has good performance, but weak binding force leads to the failure of large diamond coating. Micrometer diamond film hardness is higher, surface roughness control is difficult, will lead to a coarse metal surface.
【Conclusions】Based on this analysis, a method of in-situ deposition of nanometer diamond coating on micron diamond coating is proposed in this study, which can effectively improve the service life of wire drawing die, the wire drawing distance can be increased to more than 100km.