Surface Morphology and Properties of Diamond Etched by MnO2 Powder

Synthetic diamond crystallites were successfully etched by MnO2 powder. The effect of etching behavior on the surface morphology and properties of the treated diamond crystallites was investigated. Results showed that the etching intensity of both {100} and {111} planes increased as temperature increases, and the {111} plane was etched more significantly than the {100} plane under the same conditions. After etching, the morphology of etched pits on the {100} plane transformed from quadrilateral to octagonal, while those on the {111} plane were distinguished by triangular conical bulges. The compressive strength of a single diamond particle declines from 255 to 202 N, and the impact toughness decreases from 90.11% to 86.3%. More significantly, compared with raw diamond, the maximum flexural strength of the Cu-matrix bonding diamond block with etched diamonds increased from 394.2 to 464.9 MPa, an increase of 17.9%, and the cutting ratio of the diamond saw blades decreases from 17.5 to 9.67 g/m2. The ability to produce an anchoring connection between the etched diamond and the matrix accounts for the performance increase in diamond tools. The etching mechanism is a reaction between MnO2 and the C atom on the diamond surface.