Synergistic Etching of Diamond Particles Using Fe–CuO Binary System

This paper systematically investigates the synergistic etching behavior and mechanism of diamond particles using a binary Fe–CuO system at 900°C. XRD analysis indicated that a solid-state reaction occurred between Fe and CuO, generating FeO, Cu, and trace amounts of CuFe2O4, with FeO and Fe constituting the active etching medium. SEM observations revealed a distinct crystallographic dependence of the etching effects: the {100} surfaces exhibited regularly arranged square or rectangular etch pits with boundaries aligned along crystallographic directions, showing highly uniform morphologies; while the {111} surfaces displayed numerous ring-shaped etch pits, whose size and density varied significantly with the CuO content. The study demonstrated that CuO content played a key role in modulating the etching behavior: an appropriate addition significantly enhanced etching, particularly on the {111} surfaces and grain boundaries, whereas excessive addition led to weakened etching. Mechanistically, the exothermic Fe–CuO reaction provided localized high temperatures and highly active interfaces; the Fe–FeO synergy established a dynamic redox cycle enabling sustained etching; and CuO facilitated the initial reaction stage through auxiliary reduction and nano-effects.