Use of slag (CaO-Al2O3-SiO2-MgO) droplet as a catalyst to grow MgO whiskers through VLS mechanism

Abstract

Abstract MgO whiskers have a variety of potential applications like nanoelectronics, sensing devices and to improve mechanical properties of high temperature superconductors like MgB2, and MgO-C refractory used in the steel industry. The growth of whiskers is known to be catalyzed by the presence of a liquid droplet at the whisker tip, generally known as the vapor-liquid-solid (VLS) growth mechanism. Several metallic systems like Au, Mg-Si, Al-Mg and Ni have been used as a catalyst. In this work, it was found that a CaO-Al2O3-MgO-SiO2 mixture (a typical ladle slag used in steelmaking) can facilitate the growth of MgO whiskers. This was first observed, in this work, during a steel-slag equilibrium experiment conducted in a confocal laser scanning microscope (CLSM) using an MgO crucible. MgO whiskers observed after the experiment had a slag droplet on the tip of whiskers. Subsequently, targeted experiments were conducted to find the possible sources of magnesium vapor and the usability of slag to grow whiskers in MgO-C refractory. Results show that the slag can facilitate the growth of MgO whiskers in an MgO-C pellet.