In-situ low-energy synthesis of controllable Sialon at diamond interface and its growth mechanism

Abstract

Low-energy synthesis has always been a challenge for Sialon. Meanwhile, sialon with controllable morphology is difficult to synthesize at a lower temperature. In this paper, silicon powder, diamond powder, pure aluminium, Al–12Si alloy and Al2O3 powders are selected as raw materials. Temperature design scheme is 1100 °C for 3 h and insulation at 1100 °C for 2 h + 1200 °C for 1 h. Sialon nanowires, Sialon nanoparticles and Sialon nanorods are synthesized at the diamond interface, respectively. It is worth noting that Sialon nanotubes were synthesized at the diamond interface during the experiment. The internal structure of the sample was analyzed by transmission electron microscopy (TEM). Microstructure of sample fracture is observed by scanning electron microscopy (SEM). The phase analysis and component analysis of the samples were carried out by X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). It is proved that the diamond interface first generated nano-SiO2. It is found that there are two formation mechanisms of SiO2 on diamond surface, one is formed by oxidation of Si powder, the other is formed by chemical reaction of Si powders and Al2O3 powders. Through the study of microstructure, the densification process of nano-SiO2-Al2O3 composite layer is discussed, and the possible nucleation and growth mechanism of four kinds of nanostructures are analyzed. The discovery of controllable Sialon nanostructure through low-energy synthesis of diamond interface has potential prospects in functionalized diamond composites.