Exploring the activation energy of diamond reacting with metals and metal oxides by first-principle calculation

Abstract In the process of polishing the diamond substrate, when the metals and metal oxides are used as the reactive abrasive to achieve reaction removal of the surface material of the substrate, a higher material removal rate and a better surface quality of the substrate can be achieved. To explore the difficulty of diamond reacting with different kinds of metals and metal oxides, the activation energies of the reaction between diamond and metals, as well as between diamond and metal oxides, were obtained by first-principle calculation. For the transition metals in the fourth period of the Periodic Table of the Elements, when they react with diamond and form corresponding metal carbides, the order of activation energy from low to high is Mn, Fe, V, Ti, Cr, Co, Ni, Zn, and Cu. The calculated results are in accord with unpaired “d” electrons theory and previous studies. And when diamond reacts with MnO, FeO, CoO, NiO, and CuO to form metals and CO, the calculated activation energy in descending order is MnO, FeO, CoO, NiO, and CuO. The initial reaction temperature between diamond and these metal oxides is determined by thermal analysis, and the relative magnitude of the initial reaction temperature is consistent with the relative size of the calculated activation energies. That proves the rationality of the calculation results. The reactants and products of diamond reacting with NiO and CuO are detected by XRD, the results indicate NiO and CuO are reduced to Ni and Cu by diamond, showing the redox reaction takes place between diamond and metal oxides.