Investigation of the atomistic behavior in nanofinishing single-crystal aluminium nitride with hydroxyl radical ∙OH environment

Abstract

The effect of depth of pressing and sliding velocity on chemical reaction, wear and atom removal mechanisms was investigated in nanofinishing single-crystal aluminum nitride with hydroxyl radical ∙OH environment. The simulation results show that aluminum nitride can be oxidized by hydroxyl radical ∙OH from the perspective of free energy change. Only chemical action, the decomposed atoms in the solution form bonds with the Al atoms on the aluminum nitride surface, and the bonds are expressed in the form of O-[Al]n, H-[Al]n and OH–[Al]n. However, no Al atoms were discovered to break away from the substrate. The potential energy of substrate and the number of Al-O bonds are positively correlated with the depth of pressing and sliding velocity, and the degree of chemical reaction can be promoted by strong mechanical behavior. The tangential force relies on interfacial Al-C and AlOC bonds, the more interfacial bonds between substrate and abrasive, the more severe wear of the substrate surface. The sliding of diamond abrasive leads to the amorphous evolution of the crystal structure, and the separation of atoms from the initial position produces defects, which destroys the stable covalent bond structure of aluminum nitride. As a result, the total number of dangling bonds (i.e. unsaturated bond) of surface layer atoms increases, and the greater the depth of pressing and velocity, the more obvious this phenomenon will be, and the more atoms will be removed. In this study, atomic removal behavior of aluminum nitride was systematically analyzed at atomic scale, which will provide theoretical guidance for ultra-precision and low-damage processing of aluminum nitride.