A model for manufacture of nano-sized smart materials free from impurities

Abstract

The importance of nano-sized smart materials in structural engineering, biomedical engineering, and in military applications is discussed. It is shown that the solidification of poorly conducting alloys involved in the manufacture of these materials gives rise to surface and convective instabilities. Different types of surface and convective instabilities are briefly discussed. These instabilities produce a mushy zone regarded as dendrites of nano-sized crystals. These dendrites arising from instabilities are regarded as impurities. To manufacture nano-sized smart materials free from impurities, it is essential to control both surface and convective instabilities. We discuss here briefly, different types of convective and surface instabilities in a poorly conducting fluid. We also discuss different mechanisms of control of these instabilities. Different analytical and numerical techniques used to investigate these instabilities under different boundary conditions are discussed. In this review the moment method is explained to find the condition for the onset of convection, and porous lining is used to suppress the growth rate of surface instability. This is useful in the manufacture of nano-sized smart materials free from impurities. Different methods to obtain the required basic equations and the corresponding boundary conditions are briefly discussed.