Optimization of deposition parameters for the growth of micro-edge diamond abrasive grains using HFCVD method

Abstract

Precision grinding form fine grinding stripes with the micro-cutting effect of the abrasive micro-edges and obtain a high-precision and low-roughness machined surface. Due to the extremely high hardness and wear resistance, it is challenging for diamond abrasive grains to produce micro-cutting edges on the surface through grinding wheel dressing. In this paper, diamond abrasive grains with micro-edges are fabricated using hot filament vapor deposition (HFCVD) method. The graphite disc is the carrier on which high temperature and high pressure (HPHT) diamond seeds are distributed uniformly by patterned masks. Micro-edge structures are generated on the surface of grown diamond abrasive grains after chemical vapor deposition. The experimental results show that the grown diamond abrasive grains maintain the same cube-octahedral shape as seeds under the conditions of substrate temperature of 900 °C, reactive pressure of 4500 Pa, and carbon source concentration of 1 %. At the same time, numerous polycrystalline micro-edges with homogeneous distribution grow on the surface of diamond abrasive grains, and the two-dimensional (2D) size and protrusion height of micro-edges increase with the growth duration. The micro-edges are of high diamond quality with few impurities and defects and are equal in height. In addition, the analysis results of X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) imply that the optimal deposition parameters result in the preferred orientation of the crystals in the 〈111〉 direction, forming the pyramidal (111)-faceted micro-edges on the surface of the abrasive grains.